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Revista mexicana de fitopatología

versión On-line ISSN 2007-8080versión impresa ISSN 0185-3309

Rev. mex. fitopatol vol.39 no.spe Texcoco  2021  Epub 30-Nov-2022 

COVID-19: The Virus, Disease and Epidemiology

Analysis of chronic diseases associated to SARS-CoV-2 infection in children and young people in Mexico

Ikuri Álvarez-Maya*  1 

Gustavo Mora-Aguilera2 

Gerardo Acevedo-Sánchez2 

1 Biotecnología Médica y Farmacéutica, Centro de Investigación y Tecnología Aplicada de Jalisco (CIATEJ). Avenida Normalistas 800, Guadalajara, Jalisco, México;

2 Laboratorio de Análisis de Riesgo Epidemiológico Fitosanitario (LANREF), Colegio de Postgraduados Campus Montecillo (COLPOS), km 36.5 Carretera México-Texcoco. Montecillo, Estado de México, C.P. 56230.


The emergence of COVID-19, a disease caused by SARS-CoV-2, was first reported in December 2019. It then spread in pandemic proportions, creating a human health emergency that was declared a pandemic by the World Health Organization. The airborne transmission of the SARS-CoV-2 virus, mainly through droplets of saliva, has been highly effective, depending on the viral variant. The present study provides clinical-epidemiological information on the general population without discriminating by socioeconomic and occupational factors. A total of 8507 positive cases, with 408384 official metadata, were analyzed. These cases correspond to the exponential phase of the first epidemic wave (March-June 2020) in Mexico. The cohort consisted of children and young people up to 20 years of age. The putative risk factors for SARS-CoV-2 infection due to chronic diseases were also analyzed. In this cohort, the frequency of SARS-CoV-2 infection was 3%, with a 9% rate of active infections and a mortality rate of 1%. The greatest association was between COVID-19 and metabolic diseases, with 31%. This is the first study that analyzed the health conditions associated with COVID-19 infection in children and young people in Mexico during the first SARS-CoV-2 epidemic wave, in the absence of acquired or induced immunity factors. The results, although preliminary, may contribute to the management of COVID-19 patients during the prevention and hospitalization stages. Given the sustained expansion of the epidemic and the greater availability of data, it would be useful to make an integrative analysis of the rural population, which has remained active in the labor market given that agriculture is considered an essential activity.

Key words: SARS-CoV-2; COVID-19; Comorbidity; Epidemiology; Children and young people.


En diciembre de 2019 se reportó la ocurrencia de COVID-19, enfermedad causada por SARS-CoV-2, extendiéndose a nivel pandémico. COVID-19 es una emergencia de salud humana declarada pandemia por la Organización Mundial de la Salud. La transmisión por vía aérea del virus SARS-CoV-2, principalmente a través de microgotas de saliva, ha resultado altamente efectiva dependiendo de la variante viral. Este trabajo aporta información clínica-epidemiológica de población en general sin discriminar por factores socio-económicos y ocupacionales. Este trabajo analizó 8507 casos positivos con 408384 metadatos oficiales correspondientes a la fase exponencial, marzo-junio 2020, de la primera ola epidémica en México. El cohorte correspondió a niños y jóvenes hasta 20 años e incluyó el análisis de putativos factores de riesgo a la infección de SARS-CoV-2 por enfermedades crónicas. En este cohorte, la frecuencia con infección por SARS-CoV-2 fue del 3%, del cual, se tuvo una tasa del 9% de infecciones activas. La mortalidad fue del 1%. La mayor asociación de COVID-19 se tuvo con enfermedades metabólicas con 31%. El presente estudio es el primer reporte que analiza las condiciones de salud asociadas al proceso de infección por COVID-19 en niños y jóvenes del país en la primera fase epidémica SARS-CoV-2 en ausencia de factores de inmunidad adquirida o inducida. Los resultados, aunque preliminares, pueden contribuir el manejo de pacientes en etapas prevención y hospitalarias COVID-19. Ante el progreso sostenido de la epidemia y mayor disponibilidad de datos, se recomienda un análisis integrativo con énfasis en la población rural, la cual se ha mantenido laboralmente activa por considerase la agricultura una actividad esencial.

Palabras clave: SARS-COV-2; COVID-19; comorbilidad; epidemiología; niños y jóvenes.

On December 31, 2019, the WHO reported a cluster of cases of “pneumonia of unknown origin” in Wuhan, China. In January 2020, the Chinese health authorities confirmed that these cases were associated with the coronavirus (Hu et al., 2020). The disease was named coronavirus disease 2019 (COVID-19) by the World Health Organization (WHO).

Also in January 2020, the WHO declared the SARS-COV-2 infection a pandemic-level health emergency (Bassareo et al., 2020). It was demonstrated that the SARS-CoV-2 virus spread mainly via droplets of saliva when a person spoke or coughed. Since the virus is transmitted by air, it has proven to be highly transmissible among people of different ages and different health conditions (Karia et al., 2020).

A recent study conducted in China reported the clinical characteristics of 41 patients with confirmed SaRS-CoV-2 diagnosis, of which 13 (32%) patients reported underlying diseases such as cardiovascular disease (CVD), diabetes, hypertension, and chronic obstructive pulmonary disease (COPD) (Huang et al., 2020).

The rapid global spread of the SARS-CoV-2 virus and the reported severity of some cases of COVID-19 justify the global effort to develop effective preventive and management strategies such as targeted therapies and vaccines.

As of May 2020, 3,519,901 COVID-19 cases had been reported in 187 countries on all continents, with 247,630 deaths (, 2020). In general, the first wave of positive cases showed that the population of children, adolescents, and young people were less affected than older adults, but the data on the epidemiological and clinical characteristics of pediatric COVID-19 are very deficient, based mainly on limited case series (Galli et al., 2020). A study of 72,314 cases by the China Center for Disease Control and Prevention showed that about 2% of the patients were under 19 years of age. However, specific clinical information is still scarce (Lu et al., 2020).

To estimate the prevalence of chronic diseases and comorbidities in the population of children and young people positive for SaRS-CoV-2 in Mexico, without including rural regions or those related to the agricultural sector, an epidemiological analysis was carried out in individuals under 21 years of age. The objective was to determine the effect of health conditions potentially associated with COVID-19 infection and mortality. The potential risk for the child population could be high, considering that, in Mexico, approximately one-third of the children population suffers from obesity and diabetes (UNICEF, 2019), and that these diseases have been shown to increase the risk of infection and mortality from COVID-19 in the adult population. In the return to the ‘new normality’, several new COVID-19 outbreaks throughout the world have affected populations that were apparently non-susceptible during the first wave, which suggests that the return of in-person school could pose serious risks to children and young people. In the face of these risks, the epidemiological alert for children and actions such as the recent changes to regulations on food labeling to reduce the consumption of products high in fat and carbohydrates (Basto-Abreu et al., 2020), are important measures that can contribute to the management and mitigation of the effects of COVID-19 on the population of children and young people.

Materials and methods

Data Collection

The data for the analysis were obtained from the official database of positive COVID-19 cases, which is updated daily by the Mexican Federal Government. A total of 8507 cases and 408384 records were analyzed using MS Excel. In the database, individual chronic diseases were grouped according to metabolic, cardiovascular, respiratory, and other characteristics. The group of cases without chronic diseases was also analyzed. The group of deceased cases was formed with data obtained from official death records. The status of each case could be one of the following: deceased, active, or recovered. The Active Cases category included those conditions for which the first date of symptoms was less than 14 days before. The recovered cases category included those for which a date of death had not been reported and for which the number of days between the onset of symptoms and the date of analysis was greater than 14.

Relative Frequency Analysis

The database with 8507 cases of individuals under 21 years of age was segmented by the variables under study using MS Excel. The percentage of relative frequency was calculated for each of the analyzes (, 2020). Matrices were used to analyze the subgroups of Recovered, Active, and Deceased cases. The frequency, in the total number of cases, of Cardiovascular, Metabolic, and Respiratory Diseases, of Non-Comorbidities and Other conditions was also assessed. The group of deceased infants was also segmented by the different comorbidity variables mentioned above. The cases of death from COVID-19 were classified according to the state of residence of the patient.

Results and discussion

Population under 21 years of age with SARS-CoV-2 infection in Mexico

The frequency of children and young people of school age that became infected by SARS-CoV-2 was estimated by analyzing the subgroups of Recovered, Active, and Deceased cases within the total number of infections in the population of children and young people. Out of a total of 268,461 COVID-19 cases as of June 2020, there were 8,507 (3.1%) cases of individuals under 21 years of age with SARS-CoV-2 infection. Of this population of infected minors, 81% were infants who recovered from the disease, 16% were active cases and 2% were individuals who died (Figure 1A). The highest number of deaths occurred in the State of Mexico, with 33 cases (24%), while Mexico City and Baja California had 13 (9.4%) and 12 (8.7) deaths, respectively.

Study of chronic diseases associated with SARS-CoV-2 infection among a population of children and young people under 21 years of age

The progression of the SARS-CoV-2 infection has been associated with the presence of underlying health conditions. An analysis of the frequency of diseases associated with SARS-CoV-2 infection showed that cardiovascular diseases were present in 1% of the cases analyzed, while metabolic diseases (obesity) were present in 10% of pediatric cases. Respiratory diseases were present in 6% of the cases of children and young people with COVID-19 (Figure 1B). In 81% of the cases positive for COVID-19, no chronic diseases or comorbidities were present, which contrasts with 49.5% in adults (Álvarez-Maya et al., Unpublished).

Main chronic diseases in cases of children and young people who died from SARS-CoV-2 infection

The analysis showed that of 137 deceased cases, 13 (10%) were associated with a cardiovascular condition, while 42 cases (31%) were associated with a metabolic disease. The percentage of children and young people who died COVID-19 and had no chronic diseases was 46%, higher than the 28.2% reported for adults by Álvarez-Maya et al. (unpublished). Finally, respiratory diseases were associated with 1% of the deceased children and young people (Figure 1C).

Figure 1 A) Percentage (%) of Population (PN) under 21 years old positive to SARS-COV-2 in Mexico. B) % of PN positive to SARS-CoV-2 by category of chronic disease. C) % of deaths by category of chronic disease in PN positive for SARS-CoV-2. 

The mortality rate from COVID-19 for infants in Mexico is three times that of the United States. The latter is one of the countries with the highest infection rates worldwide, but it had only 30 cases of infant deaths (5-14 years) during the pandemic (, 2020). The general perception is that COVID-19 symptoms are milder among young people; however, the present study shows that the risk of infection is not negligible, especially in cases with comorbidities such as diabetes or obesity. It is worth remembering that of the 137 deceased cases analyzed in the present work, 13 (10%) were associated with a cardiovascular condition, while 42 cases (31%) were associated with metabolic disease (Diabetes and Obesity).

It is also generally considered that children with COVID-19 do not present the classical symptoms shown by adults. Therefore, children are diagnosed based on a sum of clinical and analytical data. The first symptoms in children are sometimes severe abdominal pain, diarrhea, or vomiting. It can also include conjunctivitis, skin rashes, mucous membrane changes, enlarged lymph nodes, swollen hands and feet, sore throat, cough, fainting, irritability, and confusion. Respiratory symptoms are not always present. Myocarditis (inflammation of the heart muscle) is common. Other symptoms may include pericarditis, valvulitis, and coronary artery abnormalities, such as dilatation and aneurysms (Ruan et al., 2020). It is especially difficult to recognize the disease in babies; in many cases, COVID-19 is not suspected because due to the lack of an obvious clinical picture (Guo et al., 2020).

In obesity cases, excess abdominal fat compresses the diaphragm, reducing lung capacity and worsening most respiratory diseases. Another factor that makes obese people more vulnerable is chronic inflammation and the increased risk of venous thrombosis, a cause of mortality associated with spending too much time in bed (Gazzaruso et al., 2020). At the cellular level, obesity alters the inflammatory and immune response. Adipose tissue, which is found in excess in obese patients, expresses the ACE2 protein, used by SARS-CoV-2 to infect cells (El-Sayed et al., 2020). So far, some studies have focused on children with COVID-19 in various parts of Europe and the United States; however, it is unclear if the disease has gone undetected in other countries. Little specific information is available on the therapeutic effectiveness against SARS-CoV-2 infection in infants. Anti-inflammatory treatments have been used against it, including intravenous immunoglobulin and corticosteroids (Pereira et al., 2020).

Mexico is the second country with the highest incidence of childhood obesity, according to 2019 data from the Organization for Economic Cooperation and Development (OECD, 2020). Furthermore, hypertension is present in 20.87% of adult COVID-19 patients, obesity in 20.44%, diabetes in 17.46%, and tobacco use in 8.24% of confirmed COVID-19 cases (Álvarez-Maya et al., unpublished). Recent studies carried out by Bastos-Abreu et al. estimated that new food labeling regulations can help reduce the prevalence of obesity in the country, since they have been associated with an average caloric intake reduction of up to 36.8 kcal/day/person (23.2 kcal/day from drinks and 13.6 kcal/day from snacks). It is estimated that five years after the implementation of these new labeling regulations, the caloric intake reduction could reduce the average weight of obese people by 1.68 kg, which would translate into a reduction of the prevalence of obesity by 4.98% (14.7% with respect to the baseline). This, in turn, would represent 1.3 million fewer cases of obesity and a reduction of US $1.8 billion in indirect costs. It should be noted that that study was carried out before the COVID-19 pandemic, which means that the effect of the new labeling regulations could be even greater, considering the other measures that have been implemented, such as the prohibition to sell “junk” food in schools in the state of Oaxaca (

The present study is the first analysis of the health conditions associated with infection and mortality by SARS-CoV-2 in children and young people in Mexico. The results can be used as a basis for the management of COVID-19 patients and for designing public health strategies that prevent further infections.


In Mexico, the population of individuals under 21 years of age with SARS-CoV-2 infection showed an association with cardiovascular, metabolic, and respiratory diseases, mainly. Although the frequency of children and young people with COVID-19 infection is 3% in Mexico, 9% of these cases are still in the active phase of the infectious process. Mortality cases (1%) were mainly associated with metabolic diseases (31%), considering obesity as the main metabolic disease associated with COVID-19. It can be concluded that obesity is one of the main risk factors for mortality from SARS-CoV-2 infection in individuals under 21 years of age, which is consistent with the official decrees that consider obesity an epidemiological alert for children. The present study demonstrates the need to consider children and young people as a population at risk in the face of new normality scenarios that imply the return to in-person school activities. Furthermore, the present study highlights the urgent need for a comprehensive review of the actions of the health sector and associated institutions. Moreover, the study provides some guidelines for designing public health policies that reduce the risk of mortality from COVID-19 such as changing the periodicity of nutrition evaluation instruments and using epidemiological indicators that have a positive effect on the health culture of Mexican society. However, it is important to study the relationship between COVID-19 and comorbidities in the rural population, considering the limitations of rural health and nutrition systems and the fact that agricultural workers did not stop working during the pandemic.

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Received: March 06, 2021; Accepted: April 29, 2021

*Corresponding author:

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