Prevalencia de virus respiratorios en pacientes pediátricos atendidos entre 2020 y 2023 en un hospital de Ciudad de México por sintomatología compatible con infección respiratoria viral

Prevalence of respiratory viruses among pediatric patients treated between 2020 and 2023 at a hospital in Mexico City due to symptoms compatible with viral respiratory infections

Introducción. Las infecciones respiratorias representan una causa importante de mortalidad en todo el mundo. En México no hay datos oficiales sobre la prevalencia de virus respiratorios en niños y adolescentes con sintomatología de infección respiratoria aguda (IRA) y la literatura sobre el tema es limitada.

Objetivos. Determinar la prevalencia de virus respiratorios en población pediátrica (<17 años) atendida en un hospital público de Ciudad de México (México) por sintomatología compatible con IRA entre 2020 y 2023 y explorar los factores asociados con la presencia de estos virus.

Materiales y métodos. Estudio transversal analítico realizado con datos de 253 pacientes pediátricos llevados entre marzo 30 de 2020 y mayo 9 de 2023 al Hospital Juárez de México a consulta por sintomatología compatible con IRA. Se realizaron análisis bivariados para evaluar diferencias entre los pacientes que dieron positivo para uno o más virus respiratorios y aquellos en los que el resultado fue negativo (chi cuadrado de Pearson o prueba exacta de Fisher y prueba de U de Mann-Whitney); la asociación entre la presencia de diferentes síntomas y la detección de al menos un virus respiratorio, y la asociación entre las variables clínicas y epidemiológicas consideradas y la presencia de los diferentes virus respiratorios (prueba de chi-cuadrado de Pearson y cálculo de RP con sus respectivos IC95%).

Resultados. La mediana de edad de los pacientes fue 3 años (RIQ: 7 años) y 52.17% eran varones. La prueba de RT-PCR fue positiva en 41.89%, y enterovirus/rinovirus (13.04%) y VSR (9.09%) fueron los virus respiratorios más frecuentes. El SARS-CoV-2 solo se detectó en 2.77%. La fiebre (75.10%) y la tos (68.38%) fueron los signos y síntomas compatibles con infección respiratoria viral más comunes. Se encontró una asociación positiva y estadísticamente significativa entre tener neumonía y la presencia de enterovirus/rinovirus (RP: 2.14; p<0.001) y entre tener entre 1 y 4 años y la presencia de enterovirus/rinovirus y parainfluenza (RP: 1.64; p=0.02 y RP: 1.78; p=0.04). El requerimiento de hospitalización y la presencia de SARS-CoV-2 tuvo asociación negativa (RP: 0.75; p=0.004). Los siguientes síntomas o signos clínicos se asociaron significativamente con la detección de al menos un virus respiratorio: tos, disnea, rinorrea, polipnea, vómito (p<0.05).

Conclusión. En aproximadamente 40% de los pacientes se detectó al menos un virus respiratorio, siendo los enterovirus/rinovirus los más frecuentes. Tos, disnea, rinorrea, polipnea y vómito se asociaron con la presencia de virus respiratorios. Se observó una asociación positiva entre el diagnóstico de neumonía y la presencia de rinovirus/enterovirus y entre tener entre 1 y 4 años y la detección de rinovirus/enterovirus y parainfluenza, así como una asociación negativa entre requerimiento de hospitalización y presencia de SARS-CoV-2.

Introduction: Respiratory infections are a major cause of mortality worldwide. The literature on the prevalence of respiratory viruses in children and adolescents with symptoms of acute respiratory infection (ARI) in Mexico is scarce, and there is no official data available.

Objective: To determine the prevalence of respiratory viruses in pediatric population (<17 years) treated at a public hospital in Mexico City for symptoms consistent with ARIs between 2020 and 2023, and to explore the factors associated with the presence of these viruses.

Materials and methods: An analytical cross-sectional study was conducted using data from 253 pediatric patients who were admitted to the Hospital Juárez de México between March 30, 2020, and May 9, 2023, after presenting with symptoms consistent with ARI. Bivariate analyses were performed to evaluate the differences between patients who tested positive for one or more respiratory viruses and those who tested negative (Pearson’s chi-square test or Fisher’s exact test and Mann-Whitney U test), the association between the presence of various symptoms and the detection of at least one respiratory virus, and the association between the clinical and epidemiological variables considered and the presence of different respiratory viruses (Pearson’s chi-square test and calculation of prevalence ratios with their respective 95% confidence intervals).

Results: The median age of the patients was 3 years (IQR: 7 years), and 52.17% were male. The RT-PCR test was positive for 41.89% of patients, and enterovirus/rhinovirus (13.04%) and RSV (9.09%) were the most common respiratory viruses. SARS-CoV-2 was detected in only 2.77%. Fever (75.10%) and cough (68.38%) were the most common signs and symptoms consistent with viral respiratory infection. A positive and statistically significant association was found between having pneumonia and the presence of enterovirus/rhinovirus (PR: 2.14; p<0.001) and between being between 1 and 4 years old and the presence of enterovirus/rhinovirus and parainfluenza (PR: 1.64; p=0.02 and PR: 1.78; p=0.04). Hospitalization requirement and the presence of SARS-CoV-2 were negatively associated (PR: 0.75; p=0.004). The following clinical symptoms or signs were significantly associated with the detection of at least one respiratory virus: cough, dyspnea, rhinorrhea, polypnea, and vomiting (p<0.05).

Conclusion: At least one respiratory virus was detected in approximately 40% of patients, with enteroviruses and rhinoviruses being the most common. Cough, dyspnea, rhinorrhea, polypnea, and vomiting were associated with the presence of respiratory viruses. A positive association was observed between a pneumonia diagnosis and the presence of rhinovirus/enterovirus and between being between 1 and 4 years of age and the detection of rhinovirus/enterovirus and parainfluenza; a negative association was also observed between hospitalization requirement and the presence of SARS-CoV-2.

Original Research

Daniel Yair Chavarría-Castro1 Karen Alejandra Aguirre-Raya2 Rafael Molina-Quiroz3 Thelma Urbina-Mejía2

1 Hospital Juárez de México - Hospital Epidemiological Surveillance Unit - Mexico City - Mexico.

2 Hospital Juárez de México - Pediatrics Service - Mexico City - Mexico.

3 Hospital Regional Pemex Ciudad Madero - Internal Medicine Service - Ciudad Madero, Tamaulipas - Mexico.

Open access

Received: 06/10/2025

Accepted: 10/05/2026

Corresponding author: Daniel Yair Chavarría-Castro. Unidad de Vigilancia Epidemiológica Hospitalaria, Hospital Juárez de México. Ciudad de México. México. E-mail: dr.daniel-yair.c@hotmail.com.

Keywords: COVID-19; Respiratory Syncytial Virus; Rhinovirus; Viral Pneumonia; Hospitalization; Comorbidity.

Palabras clave: COVID-19; Virus Sincitial Respiratorio; Rinovirus; Neumonía viral; hospitalización; comorbilidad.

How to cite: Chavarría-Castro DY, Aguirre-Raya KA, Molina-Quiroz R, Urbina-Mejía T. Prevalence of respiratory viruses among pediatric patients treated between 2020 and 2023 at a hospital in Mexico City due to symptoms compatible with viral respiratory infections. Rev. Fac. Med. 2026;74:e123203. English. doi: https://doi.org/10.15446/revfacmed.v74.123203.

Cómo citar: Chavarría-Castro DY, Aguirre-Raya KA, Molina-Quiroz R, Urbina-Mejía T. [Prevalencia de virus respiratorios en pacientes pediátricos atendidos entre 2020 y 2023 en un hospital de Ciudad de México por sintomatología compatible con infección respiratoria viral]. Rev. Fac. Med. 2026;74:e123203. English. doi: https://doi.org/10.15446/revfacmed.v74.123203.

Copyright: ©2026 The Author(s). This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International License, which permits unrestricted use, distribution, and reproduction in any medium, as long as the original author and source are credited.

Abstract

Resumen

Introduction

Respiratory tract infections are a common problem worldwide and represent a major cause of mortality (nearly 4 million deaths per year, of which 20% occur in pediatric patients) and a significant burden on healthcare systems.1 In most cases, they are caused by viruses, including influenza and parainfluenza viruses, human metapneumovirus, seasonal coronaviruses, human rhinoviruses-enteroviruses, and respiratory syncytial virus (RSV).1-3 Regarding RSV, it has been reported as one of the most frequently detected respiratory viruses in the pediatric population around the world4-6 and the primary cause of lower respiratory tract infection in children and adolescents in Latin America and Mexico.7

Before the COVID-19 pandemic, a disease caused by the SARS-CoV-2, the most common etiological agents of respiratory infections were influenza, rhinoviruses, adenoviruses, and RSV.6 Due to the preventive and public health measures adopted in most countries to contain the spread of SARS-CoV-2, the circulation of many of these viruses was significantly reduced during the first year of the pandemic, resulting in a drastic decrease in the frequency of respiratory infections, particularly in the pediatric population.2,6,7 However, the relaxation and/or elimination of these measures led to a reemergence of respiratory viruses other than SARS-CoV-2 in mid-2021.6,8 In particular, RSV had an unusual resurgence, with an atypical increase in the number of cases showing rates higher than pre-pandemic peaks and cases occurring during seasons when this virus is typically absent (summer-autumn), following different patterns compared to previous years.6,7

Although Mexico has an epidemiological surveillance system for viral respiratory diseases (VRD) that aims to identify suspected and confirmed infectious cases in a timely manner and obtain epidemiological information to guide the development and implementation of measures directed at controlling and preventing the spread of these viruses in the country,9 there are currently no pertinent official data regarding their prevalence in children and adolescents. Furthermore, recent literature on the subject is scarce, with few studies conducted in the country,3,8,10 some of which address only the prevalence of specific viruses, such as RSV11 and human rhinovirus,12 or conducted in specific pediatric populations (<5 years).13

Taking the above into consideration, the objectives of the present study were to determine the prevalence of respiratory viruses, including SARS-CoV-2, in pediatric population (<17 years) treated at a public hospital in Mexico City (Mexico) for symptoms compatible with acute respiratory infection (ARI) between 2020 and 2023, and to explore the factors associated with the presence of these viruses.

Materials and methods

Study type

Analytical cross-sectional study.

Study population and sample

The study population consisted of patients under 17 years of age taken to the Hospital Juárez de México between March 30, 2020, and May 9, 2023, for a medical consultation due to the presence of signs and symptoms compatible with ARI, such as cough, fever, headache, dyspnea, myalgia, arthralgia, among others. Sample size was calculated using the sample size formula for non-finite populations, with a 95% confidence level, a 5% margin of error, and an expected proportion of 18.7%,14 resulting in a sample size of 234 patients, to which an additional 20% was added to account for attrition, for an n of 280.. The expected proportion of 18.7% was defined based on the SARS-CoV-2 seroprevalence reported in the study by Canto-Osorio et al.14 for Mexican children and adolescents who participated in the Encuesta Nacional de Salud y Nutrición 2020 sobre COVID-19 (National Health and Nutrition Survey 2020 on COVID-19), in which seroprevalence was 15.9%, 20.1%, 25.7%, and 27.6% for children aged 3 to 5 years, 6 to 12 years, 13 to 15 years, and 16 to 19 years, respectively, and 18.7% and 26.7% for elementary school children (3-12 years) and secondary school children (13-19 years), respectively.

Only patients who underwent a reverse transcription polymerase chain reaction (RT-PCR) test for the detection of respiratory viruses were included; samples were processed according to the guidelines of the epidemiological surveillance system for viral respiratory diseases.9 Considering the calculated sample size, once the medical records of patients <17 years old with suspected ARI as the reason for consultation or admission during the study period were identified, 280 were selected through simple random sampling. Of these, 27 were excluded because they had not undergone an RT-PCR test, resulting in a final sample of 253 patients.

It should be noted that the Hospital Juárez de México is a public tertiary care hospital in Mexico City that treats populations of all ages from all over the country, mainly from Mexico City and nearby states.

Procedures and variables

Once selected, the following information was obtained for each patient from their medical records: age; biological sex; place of residence (Mexico City/State of Mexico, or others); time elapsed between symptom onset and consultation; observed signs and symptoms compatible with ARI; presence of comorbidities (diabetes, asthma, obesity, heart disease, among others), severe acute respiratory infection (SARI), and pneumonia; cohabitation with individuals with acute or recent respiratory tract infections (symptoms within the last two weeks); type of management (in-hospital or outpatient); intubation requirement; admission to the intensive care unit; RT-PCR result and type of respiratory virus identified; and status at discharge (deceased or alive).

Statistical analysis

The information was entered and organized in a Microsoft Excel spreadsheet and then exported to Stata (version 14) to perform statistical analyses.

Data are described using absolute frequencies and percentages for qualitative variables and medians and interquartile ranges for quantitative variables, as they showed a non-parametric distribution (Kolmogorov test). The prevalence of each respiratory virus was calculated by dividing the number of cases in which the virus was detected via RT-PCR by the total number of patients with suspected ARI included in the study, expressed as a percentage (i.e., multiplied by 100). The prevalence of signs and symptoms compatible with ARI was calculated in the same manner (number of cases divided by the total number of patients multiplied by 100).

A bivariate analysis (Pearson’s chi-square test or Fisher’s exact test and Mann-Whitney U test) was performed to evaluate differences in the analyzed variables between patients who tested positive for one or more respiratory viruses by RT-PCR and those who tested negative. A bivariate analysis was also conducted to evaluate the association of each sign and symptom with a positive RT-PCR result for respiratory virus detection; the strength of the association was quantified by calculating prevalence ratios (PR) with their respective 95% confidence intervals (95%CI), and statistical significance was determined using Pearson’s Chi-square test.

Lastly, a bivariate analysis was performed (Pearson’s chi-square test and calculation of PR with their respective 95%CI) to evaluate the associations between the analyzed clinical and epidemiological variables and the presence of the different respiratory viruses. For this final analysis, the variables age (<1 year, 1-4 years, 5-10 years, and >11 years) and time elapsed between symptom onset and consultation (<5 and >5 days) were categorized. A statistical significance level of p<0.05 was considered in all statistical analyses.

Ethical considerations

The present study followed the ethical principles for medical research involving human subjects established in the Declaration of Helsinki15 and was approved by the Institutional Ethics Committee of the Hospital Juárez de México according to Minutes No. CI/037/2025 dated January 28, 2025 (folio HJM 237/24-R). Being a study that collected data from clinical records, signed informed consent from the legal representatives of the patients was not required.

Results

The median age of the patients was 3 years (IQR: 7 years); 52.17% (n=132) were male; 94.86% required hospitalization; 55.34% and 40.71% were diagnosed with SARI and pneumonia, respectively; only 11.07% had one or more comorbidities; and the median time elapsed between symptom onset and consultation was 3 days. Regarding the detection of respiratory viruses, the RT-PCR test was positive in 41.89% (n=106), with significant differences observed between groups in the presence of SARI (65.09% vs. 48.30%; p=0.008), the presence of pneumonia (49.06% vs. 34.69%; p=0.022), and the time elapsed between symptom onset and consultation (2 days [IQR=2] vs. 2 days [IQR=3]; p=0.031). The characteristics of the sample are presented in Table 1.

Table 1. Characteristics of pediatric patients with suspected viral respiratory disease as the reason for consultation/admission between March 2020 and May 2023 (n=253).

Variables		Total (n=253) n (%)	Positive for respiratory viruses (n=106)	Negative for respiratory viruses (n=147)	p-value
Age (years) Median (IQR)		3 (7)	2 (4)	3 9)	0.339ª
Sex (male)		132 (52.17)	53 (50.00)	79 (53.74)	0.557b
Residence in Mexico City or State of Mexico		248 (98.02)	104 (98.11)	144 (97.96)	1.00c
Time elapsed between symptom onset and consultation (days) Median (IQR)		2 (3)	2 (2)	2 (3)	0.031a
Cohabitation with individuals with acute or recent respiratory tract infections (symptoms within the last 2 weeks)		30(12.50)	8(7.55)	22(14.97)	0.72b
Comorbidities (yes)		28(11.07)	6(5.66)	22(14.97)	0.020b
	Diabetes	4 (1.58)	1 (0.94)	3 (2.04)	0.642c
	Asthma	13 (5.14)	5 (4.72)	8 (5.44)	0.797b
	Immunosuppression	7 (2.77)	1 (0.94)	6 (4.08)	0.244c
	Hypertensive disorders	1 (0.40)	0 (0)	1 (0.68)	1.00c
	Heart diseases	4 (1.58)	0 (0)	4 (2.72)	0.142c
	Obesity	5 (1.98)	1 (0.94)	4 (2.72)	0.403c
Presence of SARI		140 (55.34)	69 (65.09)	71 (48.30)	0.008b
Presence of pneumonia		103 (40.71)	52 (49.06)	51 (34.69)	0.022b
Type of management (hospitalization)		240 (94.86)	103 (97.17)	137 (93.20)	0.158b
	Intubation (n=240)	14 (5.83)	4 (3.88)	10 (7.29)	0.263b
	Intensive care (n=240)	13 (5.42)	3 (2.91)	10 (7.29)	0.137b
Deaths		5 (1.98)	0 (0)	5 (3.40)	0.077c

SARI: Severe acute respiratory infection.

ª Mann-Whitney U.

b Pearson’s chi-square.

c Fisher’s exact.

Source: Own elaboration.

The highest number of suspected and positive cases for respiratory viruses was recorded between September and November 2022, with October and November of that year being the months with the highest percentage of positivity for respiratory viruses in the processed samples (100% and 74.1%, respectively) (Figure 1).

Figure 1. Suspected and confirmed cases of viral respiratory disease. 2020-2023

Source: Own elaboration.

Concerning the prevalence of the different respiratory viruses, enterovirus/rhinovirus (13.04%) and RSV (9.09%) were the most frequent. SARS-CoV-2 was detected in only 2.77% of the patients (Table 2).

Table 2. Prevalence of respiratory viruses in the sample according to the results of the reverse transcription polymerase chain reaction test (n=253).

Virus	n	%
Enterovirus and rhinovirus	33	13.04
Respiratory syncytial virus	23	9.09
Influenza	17	6.72
Parainfluenza	13	5.14
SARS-CoV2	7	2.77
Metapneumovirus	7	2.77
Bocavirus	3	1.19
Adenovirus	3	1.19
Coronavirus OC43	2	0.79
Negative	147	58.10
More than one virus	2	0.79

Source: Own elaboration.

Fever (75.10%), cough (68.38%), and dyspnea and rhinorrhea (45.45% each) were the most common signs and symptoms compatible with viral respiratory infection. The following signs and symptoms were significantly associated with the presence of respiratory viruses in the bivariate analysis: polypnea (PR: 1.87, 95%CI: 1.05-3.33; p=0.03), vomiting (PR: 1.77, 95%CI: 1.01-3.11; p=0.04), rhinorrhea (PR: 1.74, 95%CI: 1.32-2.28; p<0.001), cough (PR: 1.50, 95%CI: 1.28-1.77; p<0.001), and dyspnea (PR: 1.45, 95%CI: 1.08-1.94; p=0.01) (Table 3).

Table 3. Association between the different signs and symptoms compatible with viral respiratory infection and the presence of respiratory viruses. Bivariate analysis.

Signs/symptoms	Prevalence	PR	95%CI	p-valuea
Fever	75.10	1.07	0.93-1.24	0.32
Cough	68.38	1.50	1.28-1.77	<0.001
Odynophagia	13.83	0.63	0.32-1.24	0.18
Dyspnea	45.45	1.45	1.08-1.94	0.01
Irritability	38.74	1.13	0.83-1.54	0.44
Diarrhea	13.04	0.90	0.47-1.73	0.75
Chest pain	7.51	1.90	0.79-4.58	0.14
Chills	12.25	1.14	0.58-2.21	0.69
Headache	21.34	0.81	0.50-1.33	0.41
Myalgias	11.86	0.69	0.34-1.42	0.31
Arthralgias	7.91	0.75	0.31-1.81	0.51
Impairment of the general condition	38.34	1.05	0.77-1.45	0.72
Rhinorrhea	45.45	1.74	1.32-2.28	<0.001
Polypnea	15.81	1.87	1.05-3.33	0.03
Vomiting	16.21	1.77	1.01-3.11	0.04
Abdominal pain	7.91	0.59	0.24-1.50	0.26
Conjunctivitis	8.30	1.26	0.55-2.86	0.58
Cyanosis	7.91	0.92	0.39-2.18	0.86
Anosmia	0.40	0	---	---
Dysgeusia	0	---	---	---

PR: prevalence ratios.

a Determined by Pearson’s Chi-square test.

Own elaboration.

Lastly, regarding the associations between the analyzed clinical and epidemiological variables and the presence of the different respiratory viruses, the bivariate analysis revealed that being between 1 and 4 years old was significantly associated with the detection of rhinovirus/enterovirus and parainfluenza (PR: 1.64; p=0.02 and PR: 1.78; p=0.04) and that the diagnosis of pneumonia was associated with the presence of rhinovirus/enterovirus. Additionally, a negative association was observed between hospitalization requirement and SARS-CoV-2 detection (PR: 0.75; p=0.004) (Table 4). It is important to bear in mind that although statistically significant associations with the presence of other respiratory viruses such as influenza and bocavirus were identified, they must be interpreted with caution due to the low number of recorded cases.

Table 4. Associated factors for each respiratory virus.

Characteristics	Rhinovirus/enterovirus			Respiratory syncytial virus			Influenza			Parainfluenza			SARS-CoV-2
	PR	95%CI	pª	RP	95%CI	pª	PR	95%CI	pª	PR	95%CI	pª	PR	95%CI		pª
General characteristics
Sex (male)	1.01	0.70-1.48	0.93	1.10	0.73-1.67	0.66	1.11	0.70-1.78	0.66	1.31	0.83-2.05	0.31	0.89		0.38-2.12	0.79
Residence in Mexico City or State of Mexico	1.02	1.00-1.04	0.38	1.02	1.00-1.04	0.49	0.89	0.75-1.06	0.002	1.02	1.00-1.04	0.59	1.02		1.00-1.03	0.70
Cohabitation with individuals with acute or recent respiratory tract infections (symptoms in the last 2 weeks)	0.23	0.03-1.64	0.09	1.17	0.36-3.72	0.79	0.50	0.07-3.67	0.79	0.65	0.10-4.41	0.65	3.50		0.66-18.29	0.11
Time to receive careb
>5 days	1.18	0.36-3.80	0.78	0.53	0.07-3.75	0.51	1.54	0.39-6.10	0.54	0.97	0.14-6.70	0.97	2.17		0.34-13.65	0.42
Age (years)
<1	0.56	0.24-1.30	0.15	1.36	0.93-2.86	0.10	0.22	0.03-1.49	0.06	0.59	0.16-2.17	0.40	0	0		0
1-4	1.64	1.14-2.36	0.02	1.23	0.75-2.03	0.43	1.52	0.94-2.46	0.13	1.78	1.12-2.83	0.04	1.61	0.83-3.14		0.68
5-10	1.07	0.56-2.04	0.85	0.74	0.29-1.86	0.51	1.60	0.80-3.18	0.21	0.32	0.05-2.16	0.18	0.61	0.10-3.83		0.58
>11	0.35	0.09-1.39	0.10	0	0	0	0.35	0.05-2.43	0.24	0.97	0.26-3.59	0.96	1.84	0.55-6.18		0.35
Comorbidities
One or more	0.51	0.13-2.06	0.32	0.37	0.05-2.60	0.28	0	0	0	0.68	0.10-4.65	0.69	0		0	0
Asthma	0.55	0.75-4.13	0.56	0	0	0	2.52	0.61-10.48	0.20	1.54	0.22-10.94	0.67	0		0	0
Coexisting complications
Pneumonia	2.14	1.64-2.77	<0.001	1.19	0.75-1.88	0.47	0.56	0.23-1.33	0.13	0.94	0.46-1.90	0.86	1.05		0.44-2.51	0.91
SARI	1.31	1.01-1.69	0.07	2.69	0.76-9.54	0.11	1.42	1.06-1.90	0.06	1.27	0.87-1.85	0.30	0.51		0.16-1.65	0.15
Type of management (hospitalization)
Hospitalized	1.02	0.96-1.10	0.55	1.01	0.92-1.10	0.86	1.05	1.02-1.09	0.32	1.05	1.02-1.09	0.39	0.75		0.47-1.20	0.004
Intubation	1.81	0.53-6.18	0.34	0.77	0.10-5.61	0.79	0	0	0	0	0	0	0		0	0
Intensive Care	1.21	0.28-5.23	0.80	0.83	0.11-6.12	0.86	0	0	0	0	0	0	0		0	0
Outcome
Death	0	0	0	0	0	0	0	0	0	0	0	0	0		0	0

Characteristics	Metapneumovirus				Bocavirus			Adenovirus			Coronavirus OC43
	PR	95%CI		pª	PR	95%CI	pª	PR	95%CI	pª	PR	95%CI			pª
General characteristics
Sex (male)	0.89	0.38-2.12	0.79		0.69	0.14-3.46	0.62	0.69	0.13-3.46	0.61	1.04	0.26-4.21	0.95
Residence in Mexico City or State of Mexico	1.02	1.00-1.04	0.70		1.02	1.00-1.04	0.80	1.02	1.00-1.04	0.80	1.02	1.00-1.04	0.84
Cohabitation with individuals with acute or recent respiratory tract infections (symptoms in the last 2 weeks)	0	0	0		0	0	0	0	0	0	0	0	0
Time to receive careb
>5 days	0	0	0		0	0	0	0	0	0	0	0	0
Age (years)
<1	0.56	0.09-3.47	0.50		0	0	0	1.32	0.26-6.65	0.75	1.99	0.49-8.10	0.42
1-4	0.79	0.24-2.58	0.68		1.87	0.83-4.24	0.26	1.87	0.83-4.24	0.26	0	0	0
5-10	2.60	1.31-5.16	0.03		1.46	0.29-7.36	0.67	0	0	0	2.20	0.54-8.97	0.36
>11	0	0	0		0	0	0	0	0	0	0	0		0
Comorbidities
One or more	1.30	0.20-8.27	0.78		3.08	0.60-15.90	0.22	0	0	0	0	0	0
Asthma	0	0	0		6.94	1.28-37.74	0.026	0	0	0	0	0	0
Coexisting complications
Pneumonia	0.69	0.21-2.27	0.51		1.65	0.73-3.72	0.36	0.82	0.17-4.08	0.79	0	0	0
SARI	1.57	1.14-2.17	0.10		1.82	1.63-2.04	0.12	0	0	0	0.90	0.22-3.62	0.88
Type of management (hospitalization)
Hospitalized	1.05	1.02-1.09	0.53		1.05	1.02-1.08	0.68	1.05	1.02-1.08	0.68	1.05	1.02-1.08	0.74
Intubation	0	0	0		0	0	0	0	0	0	0	0	0
Intensive Care	0	0	0		0	0	0	0	0	0	0	0	0
Outcome
Death	0	0	0		0	0	0	0	0	0	0	0	0

PR: prevalence ratios; SARI: severe acute respiratory infection.

ª Determined by Pearson’s Chi-square test.

b Time elapsed between symptom onset and seeking medical care.

Source: Own elaboration.

Discussion

In the present study, conducted in pediatric population with symptoms compatible with viral respiratory infections treated at a public hospital in Mexico City between 2020 and 2023, the most prevalent respiratory viruses were enterovirus/rhinovirus (13.04%) and RSV (9.09%). This is in line with what was reported by Khales et al.,16 who found, in a recent systematic review and meta-analysis (68 studies; 242 183 patients) that aimed to determine the prevalence of respiratory viruses other than SARS-CoV-2 in children with respiratory infections during the COVID-19 pandemic (2020-2023), that enterovirus/rhinovirus (29.1%) and RSV (11.3%) were among the most commonly detected viruses.

This finding is also consistent with information reported in studies conducted during the COVID-19 pandemic at Hospital Infantil Federico Gómez, located in Mexico City, such as that of Nieto-Rivera et al.,3 carried out with 15 552 nasopharyngeal swab samples taken from children and adolescents with symptoms of viral respiratory infection between January 2021 and March 2022, in whom rhinovirus/enterovirus (11.47%) and RSV B (5.05%) were the most frequent respiratory pathogens in the 1 603 samples in which a respiratory pathogen panel was performed. Likewise, Flores-Alanis et al,10 in 3 619 patients admitted to this same hospital between January 1, 2021, and December 31, 2022, found that these 2 respiratory pathogens were the most frequently detected (29.04% and 13.12%).

In the case of research conducted before the COVID-19 pandemic, findings are discrepant between studies. For example, similar to what was observed in our patients, Low et al.,17 in a study of nasopharyngeal swab samples from 23 306 pediatric patients with acute respiratory infection processed between 2015 and 2019 in 12 laboratories across different states in Malaysia, state that the most frequently reported respiratory pathogens were rhinovirus/enterovirus (29.7%), influenza (22.5%), and RSV (15.9%). However, in a study conducted with respiratory tract samples from 4 219 children (0-14 years) with acute respiratory infection collected across 5 hospitals in Shanghai (China) between January 2013 and December 2022, Zhang et al.18 reported that the most frequently detected respiratory viruses were influenza (8.27%) and RSV (5.14%), while rhinovirus was the fifth most frequent pathogen (4.24%). It is worth noting that in the study by Zhang et al.,18 the number of samples collected was lower at the beginning of the study period and during the COVID-19 pandemic and also that the authors state that, due to limitations in testing capacity during the pandemic, testing for SARS-CoV-2 was not performed on samples obtained during those years.

Another finding to consider is the low prevalence of SARS-CoV-2 in our study (2.77%), a fact that has also been reported in other works conducted in similar populations, such as that of Flores-Alanis et al.,10 (0.58%). This situation is consistent with relevant literature, where it is reported that the prevalence of SARS-CoV-2 during the pandemic was low in the pediatric population (0.3-6.36%).19-24

In our study, enterovirus/rhinovirus was the most frequent virus among children and adolescents with pneumonia, with a significant association observed between the presence of pneumonia and the detection of this respiratory pathogen (PR: 2.14; p<0.001). This finding is in line with what was described in the systematic review and meta-analysis by Khales et al.,16 in which rhinovirus/enterovirus was the most commonly detected pathogen in the subgroup of patients with pneumonia (97.3%).

It is also important to mention that at least one respiratory virus was detected in 41.89% of patients. Although this figure is higher than that reported in a similar population in China (30.67%; 1 294/4 219),18 it is lower than those described in Mexico (49.59%; 797/1 6073 and 59%; 2 134/3 61910), Germany (67.9%; 114/168),23 and Malaysia (79.5%; 18 538/23 306).17 A possible explanation for this discrepancy between studies could be the differing sample sizes, the periods analyzed (some before the COVID-19 pandemic, some during the pandemic, and others before and during the pandemic), and limitations relative to the detection tests, with studies conducted during the pandemic reporting a lack of tests for SARS-CoV-2 detection.18

Regarding sample characteristics, a higher proportion of males was found (52.17%), which is consistent with what has been reported in other studies on respiratory virus detection in pediatric patients with ARI or symptoms of this condition, where the prevalence of the male sex was slightly higher (50.40-63.80%) before, during, and after the COVID-19 pandemic.2-4,,6,10,17,18,23,25 In any case, biological sex showed no significant association with the detection of any specific virus.

The comorbidity rate in our cohort was low (11.07%), with asthma (5.14%) and immunosuppression (2.77%) being the most frequent. This is consistent with what was reported by Nieto-Rivera et al.,3 who found that immunosuppression (18.03%) and asthma (8.57%) were the most frequent comorbidities in the 797 patients in whom a respiratory virus other than SARS-CoV-2 was detected. Similarly, in the study by Flores-Alanis et al.,10 immunosuppression was the most frequent comorbidity (10.31%), followed by cardiovascular diseases (excluding hypertension) (4.89%) and asthma (3.23%); however, it must be borne in mind that the proportion of patients with comorbidities in that study was higher (18.87%; 683/3 619).

In the present study, fever and cough were the most common symptoms compatible with ARI, which is in line with descriptions by Nieto-Rivera et al.3 and Flores-Analis et al.10 In their studies, cough and fever and cough, fever, and rhinorrhea were the most common symptoms, respectively.

Another finding to highlight is that 1.98% of the patients died. This mortality rate contrasts with that reported by Flores-Alanis et al.,10 who recorded no deaths in their study and also with the findings by Khales et al.,17 whose systematic review reports that respiratory tract infections represent a major burden on health systems as they cause nearly 20% of deaths in pediatric patients.

In the present study, a statistically significant association was observed between asthma and bocavirus detection (PR; 6.94; p=0.026). While this finding must be interpreted with caution due to the small number of cases, it is worth noting that, according to the literature, human bocavirus is commonly identified in patients with acute wheezing, asthma, or bronchiolitis,26-28 which may be because some viruses like bocavirus promote or cause bronchial obstruction.26

In our study, being between 1 and 4 years old was associated with a higher prevalence of rhinovirus/enterovirus and parainfluenza virus, while being between 5 and 10 years old was associated with a higher prevalence of metapneumovirus. These findings partially coincide with what was described by Castillo-Salazar et al.,29 who, in a study conducted on 718 patients (outpatients and hospitalized) treated at a hospital in Mexico City between January 2022 and July 2024, classified by age as children <5 years, children >5 years, adults aged 18-59, and adults 60 years, found that, compared to adults (18-59 years), the presence of rhinovirus/enterovirus was significantly associated with both groups of children (p=0.032 and p=0.006), but metapneumovirus and parainfluenza did not show significant associations with these age groups.

Another interesting finding was the negative association between hospitalization requirement and SARS-CoV-2 detection, which could have two explanations: the mandatory requirement, according to institutional protocol, to perform rapid antigen tests for SARS-CoV-2 detection on all patients attending emergency services during the pandemic, and the preventive measures implemented within the institution, including hospitalization floors, to contain the spread of the virus. In any case, as with the association between asthma and bocavirus detection, this finding must be interpreted with caution due to the low number of SARS-CoV-2 cases.

The present study has some limitations that must be considered when interpreting its findings. First, given the nature of the data sources (medical records), there is a potential risk of information bias, as it is not possible to guarantee a standardized data registration process by all treating physicians; in any case, the hospital has an information registration protocol that helps reduce this bias. Second, although variables related to VRD severity were included, such as admission to the intensive care unit and intubation, we must acknowledge that a more exhaustive analysis of severity in these patients was lacking, leaving out variables such as nutritional status, viral load, presence of coinfections, socioeconomic factors, vaccination schedules, and clinical red flags such as hypoxemia and tachypnea, among others.

Notwithstanding the above, as evidenced earlier, literature on the prevalence of respiratory viruses in the pediatric population with ARI symptoms before and during the COVID-19 pandemic is scarce, both in Mexico and abroad, so the data reported here constitute an important contribution to the evidence on the topic. In any case, it is recommended to conduct more studies with larger and, preferably, multicenter samples, in order to confirm the relevance of identifying the pathogenic agent causing ARI in the pediatric population as an essential part of the management protocol for these patients, as this will allow for timely and appropriate treatment.

Conclusions

The present study confirms that, although SARS-CoV-2 was a major concern during the pandemic, regular respiratory viruses continued to be the main agents of VRD in the pediatric population. A respiratory virus was detected in approximately 40% of patients, with enterovirus/rhinovirus and RSV being the most frequent. Cough, dyspnea, rhinorrhea, polypnea, and vomiting were significantly associated with the presence of respiratory viruses. Finally, a positive association was observed between the diagnosis of pneumonia and the presence of rhinovirus/enterovirus, being between 1 and 4 years old and the detection of rhinovirus/enterovirus and parainfluenza, as well as an negative association between hospitalization requirement and the presence of SARS-CoV-2.

Note: The preliminary results of this study were presented in a thesis developed to obtain the degree of Pediatrician at the Universidad Nacional Autónoma de México (UNAM).30

Conflicts of interest

None stated by the authors.

Funding

None stated by the authors.

Acknowledgments

None stated by the authors.

References

1.Chen AP, Chuang C, Huang YC, Wu PF, Huang SF, Cheng NC, et al. The epidemiology and etiologies of respiratory tract infection in Northern Taiwan during the early phase of coronavirus disease 2019 (COVID-19) outbreak. J Microbiol Immunol Infect. 2021;54(5):801-7. doi: 10.1016/j.jmii.2021.05.006. PMID: 34217634; PMCID: PMC8217336.

2.Bermúdez-Barrezueta L, Brezmes-Raposo M, Brezmes-Raposo M, Gutiérrez-Jimeno M, Rodríguez-Merino E, Pino-Velázquez M, et al. Incremento de infecciones respiratorias agudas graves en niños durante la última etapa de la pandemia COVID-19 [Increase in severe acute respiratory infections in children during the last phase of the COVID-19 pandemic]. Rev Esp Quimioter. 2024;37(1):58-68. Spanish. doi: 10.37201/req/074.2023. PMID: 38116940; PMCID: PMC10874672.

3.Nieto-Rivera B, Saldaña-Ahuactzi Z, Parra-Ortega I, Flores-Alanis A, Carbajal-Franco E, Cruz-Rangel A, et al. Frequency of respiratory virus-associated infection among children and adolescents from a tertiary-care hospital in Mexico City. Sci Rep. 2023;13(1):19763. doi: 10.1038/s41598-023-47035-6. PMID: 37957308; PMCID: PMC10643542.

4.González‐Ortiz AM, Bernal‐Silva S, Comas‐García A, Vega-Morúa M, Garrocho-Rangel ME, Noyola DE. Severe Respiratory Syncytial Virus Infection in Hospitalized Children. Arch Med Res. 2019;50(6):377-83. doi: 10.1016/j.arcmed.2019.10.005. PMID: 31678896.

5.Chamarthi S, Chamarthi VS, Daley SF. Respiratory Syncytial Virus Infection in Children. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 [cited 2026 May 29]. Available from: https://tinyurl.com/3rnt5wf9. PMID: 29083623.

6.Diaz-Torres IA, Cabrera-Takane ID, Ortega-Vargas FY, Herrera-González AA, Garcia-León ML, Bautista-Carbajal P, et al. Epidemiological and Clinical Changes in RSV-Associated Pneumonia in Children in Mexico Before and During the COVID 19 Pandemic. Infect Dis Rep. 2025;17(6):139. doi: 10.3390/idr17060139. PMID: 41283343; PMCID: PMC12641674.

7.Wong-Chew RM, Noyola DE, Solórzano-Santos F, Moreno-Espinosa S, Miranda-Novales MG, Hein EO, et al. Mexican Interdisciplinary Consensus on the Diagnosis and Preventive Measures for Respiratory Syncytial Virus Infections. Arch Med Res. 2025;56(4):103183. doi: 10.1016/j.arcmed.2025.103183. PMID: 39983633.

8.Pedroza-Uribe IM, Vega Magaña N, Muñoz-Valle JF, Peña-Rodriguez M, Carranza-Aranda AS, Sánchez-Sánchez R, et al. Beyond SARS-CoV-2: epidemiological surveillance of respiratory viruses in Jalisco, Mexico. Front Public Health. 2024;11:1292614. doi: 10.3389/fpubh.2023.1292614. PMID: 38274524; PMCID: PMC10808461.

9.México. Secretaría de Salud. Secretaría de Salud. Dirección General de Epidemiologia. Lineamiento estandarizado para la vigilancia epidemiológica y por laboratorio de la enfermedad respiratoria viral [Internet]. Ciudad de México: Gobierno de México; 2024 [cited 25 May 25]. Availabe from: https://tinyurl.com/y65ycvvx.

10.Flores-Alanis A, Rodríguez-Martínez G, Saldaña-Ahuactzi Z, Parra-Ortega I, Carbajal-Franco E, Salazar-García M, et al. Demographic and clinical factors are relevant in respiratory infections among paediatric patients: a cross-sectional study in Mexico. Eur J Clin Microbiol Infect Dis. 2025;44(8):1995-2005. doi: 10.1007/s10096-025-05168-8. PMID: 40408042.

11.González-Ortiz AM, Bernal-Silva S, Comas-García A, Vega-Morúa M, Garrocho-Rangel ME, Noyola DE. Severe Respiratory Syncytial Virus Infection in Hospitalized Children. Arch Med Res. 2019;50(6):377-83. doi: 10.1016/j.arcmed.2019.10.005. PMID: 31678896.

12.Ortega-Vargas FY, Herrera-González AA, Díaz-Torres IA, Cabrera-Takane ID, Bautista-Carbajal P, García-León ML, et al. Increased Incidence of Rhinovirus Pneumonia in Children During the COVID-19 Pandemic in Mexico. Adv Virol. 2024;2024:8841838. doi: 10.1155/2024/8841838. PMID: 39512629; PMCID: PMC11540899.

13.Leija-Martínez JJ, Cadena-Mota S, González-Ortiz AM, Muñoz-Escalante JC, Mata-Moreno G, Hernández-Sánchez PG, et al. Respiratory Syncytial Virus and Other Respiratory Viruses in Hospitalized Infants During the 2023-2024 Winter Season in Mexico. Viruses. 2024;16(12):1917. doi: 10.3390/v16121917. PMID: 39772224; PMCID: PMC11680223.

14.Canto-Osorio F, Stern D, Pérez-Ferrer C, Arias-de la Garza E, Danon L, Barrientos-Gutiérrez T, et al. Seroprevalencia de SARS-CoV-2 en niños y adolescentes mexicanos en edad escolar. Salud Publica Mex. 2021;63(6, Nov-Dic):803-6. Spanish. doi: 10.21149/12847. PMID: 35099909.

15.World Medical Association. World Medical Association Declaration of Helsinki: Ethical Principles for Medical Research Involving Human Participants. JAMA. 2025;333(1):71-4. doi: 10.1001/jama.2024.21972. PMID: 39425955.

16.Khales P, Razizadeh MH, Ghorbani S, Moattari A, Saadati H, Tavakoli A. Prevalence of respiratory viruses in children with respiratory tract infections during the COVID-19 pandemic era: a systematic review and meta-analysis. BMC Pulmonary Medicine. 2025;25(1):135. doi: 10.1186/s12890-025-03587-z. PMID: 40133851; PMCID: PMC11934662.

17.Low YL, Wong SY, Lee EKH, Muhammed MH. Prevalence of respiratory viruses among paediatric patients in acute respiratory illnesses in Malaysia. PLoS One. 2022;17(8):e0265288. doi: 10.1371/journal.pone.0265288. PMID: 35921317; PMCID: PMC9348681.

18.Zhang L, Wang Y, Xu H, Hao L, Zhao B, Ye C, et al. Prevalence of Respiratory Viruses in Children With Acute Respiratory Infections in Shanghai, China, From 2013 to 2022. Influenza Other Respir Viruses. 2024;18(5):e13310. doi: 10.1111/irv.13310. PMID: 38725276; PMCID: PMC11082482.

19.Melé M, Henares D, Pino R, Asenjo S, Matamoros R, Fumadó V, et al. Low impact of SARS-CoV-2 infection among paediatric acute respiratory disease hospitalizations. J Infect. 2021;82(3):414-51. doi: 10.1016/j.jinf.2020.10.013. PMID: 33098956; PMCID: PMC7577222.

20.De Pracontal B, Lorton F, Drumel T, Coste-Burel M, Launay E, Guen CGL. Low SARS-CoV-2 prevalence in asymptomatic children during the first year of the pandemic: A French retrospective study. Arch Pediatr. 2024;31(3):176-8. doi: 10.1016/j.arcped.2023.09.019. PMID: 38326150.

21.Viart J, Engelmann I, Joannes F, Gras-Le Guen C, Haas H, Chinazzo M, et al. A very low prevalence of SARS-CoV-2 infection but a high prevalence of other respiratory virus infections in children admitted to paediatric emergency departments. Acta Paediatr. 2022;111(5):1034-8. doi: 10.1111/apa.16301. PMID: 35178741; PMCID: PMC9111352.

22.Wurm J, Ritz N, Zimmermann P. Coronavirus disease 2019 (COVID-19) in children: Evolving epidemiology, immunology, symptoms, diagnostics, treatment, post-COVID-19 conditions, prevention strategies, and future directions. J Allergy Clin Immunol. 2025;155(4):1071-81. doi: 10.1016/j.jaci.2024.11.012. PMID: 39551439.

23.Engels G, Sack J, Weissbrich B, Hartmann K, Knies K, Härtel C, et al. Very Low Incidence of SARS-CoV-2, Influenza and RSV but High Incidence of Rhino-, Adeno- and Endemic Coronaviruses in Children With Acute Respiratory Infection in Primary Care Pediatric Practices During the Second and Third Wave of the SARS-CoV-2 Pandemic. Pediatr Infect Dis J. 2022;41(4):e146-8. doi: 10.1097/INF.0000000000003460. PMID: 35175993; PMCID: PMC8919947.

24.Zurl C, Eber E, Siegl A, Loeffler S, Stelzl E, Kessler HH, et al. Low Rate of SARS-CoV-2 Infections in Symptomatic Patients Attending a Pediatric Emergency Department. Front Pediatr. 2021;9:637167. doi: 10.3389/fped.2021.637167. PMID: 33898359; PMCID: PMC8064389.

25.Sousa BLA, Carneiro‐Sampaio M, de Carvalho WB, Silva CA, Ferraro AA. Differences among Severe Cases of Sars-CoV-2, Influenza, and Other Respiratory Viral Infections in Pediatric Patients: Symptoms, Outcomes and Preexisting Comorbidities. Clinics (Sao Paulo). 2020;75:e2273. doi: 10.6061/clinics/2020/e2273. PMID: 33263633; PMCID: PMC7688070.

26.Del Rosal T, García‐García ML, Calvo C, Gozalo F, Pozo F, Casas I. Recurrent wheezing and asthma after bocavirus bronchiolitis. Allergol Immunopathol (Madrid). 2016;44(5):410-4. doi: 10.1016/j.aller.2015.07.004. PMID: 26657170.

27.Fernando TN, Dayananda D, Muthugala R. Human bocavirus: As an emerging respiratory pathogen. World J Virol. 2025;14(4):115043. doi: 10.5501/wjv.v14.i4.115043. PMID: 41479573; PMCID: PMC12754525.

28.Vallet C, Pons-Catalano C, Mandelcwajg A, Wang A, Raymond J, Lebon P, Gendrel D. Human bocavirus: a cause of severe asthma exacerbation in children. J Pediatr. 2009;155(2):286-8. doi: 10.1016/j.jpeds.2009.01.069. PMID: 19619752.

29.Castillo-Salazar M, Flores-Gallardo V, Villavicencio-Pérez MF, Pinacho-Velázquez JL, Diosdado-Franco CA, Balcázar-Ochoa LG, et al. Detection and Epidemiological Characterization of Respiratory Pathogens Causing Infections in Patients at Hospital Angeles Lindavista. Cureus. 2025;17(11):e97187. doi: 10.7759/cureus.97187. PMID: 41426914; PMCID: PMC12715028.

30.Urbina-Mejía T. Prevalencia de comorbilidades asociadas a SARS-COV-2 y otros virus respiratorios en pacientes pediátricos del Hospital Juárez de México durante la pandemia de 2020-2023 [Thesis] [Internet]. Ciudad de México: Facultad de Medicina, Universidad Nacional Autónoma de México; 2025 [cited 2026 Jun 11]. Available from: https://tinyurl.com/c5f2mdyx.