COVID-19 pandemic can affect any age group. However, as the pandemic spreads all across the globe, it is evident that children are less affected than older adults. In this regard, COVID-19 seems to be different from other viral illnesses like influenza. Influenza illness is more common in children than COVID-19.
A study from Sweden reviewed 45 research articles on the impact of COVID-19 on children. Based on this study, children represented about 2% of diagnosed cases in China, 1.2% of cases in Italy, and 5% of cases in the United States. This is significantly lower than the incidence of influenza. As per Centers for Disease Control and Prevention (CDC), during the flu season 2018-2019 in the United States, around 10% of the total flu cases affected the age group of 0-4 years.
Similarly, fatality rate or death rate of COVID-19 in older population is significantly higher, especially over 80 years of age when compared to the death rate in children. According to a study published in JAMA, death rate in adults above 80 years of age was around 15% in China and around 20% in Italy. Death rate in the age group 0-19 years in Italy was 0 and in China, it was 0.2%. These data illustrate that COVID-19 is more severe and more prevalent in adults than children.
Several theories were proposed as to why COVID-19 is milder in children. Children usually have repeated exposure to many viral infections. Immunity developed to one viral infection may have cross-immunity to other viral infections. Children may have better immunity to SARS-CoV-2 than adults because of cross-immunity.
SARS-CoV-2 virus binds to angiotensin-converting enzyme (ACE) receptor. ACE enzyme is less mature in children and ACE receptors are fewer in number when compared to adults. This may also play a role in causing COVID-19 infection in children.
Chronic smoking and underlying lung disorder is a significant cause for the rapid deterioration of COVID-19 associated respiratory illness. COVID-19 aggravates and worsens the lung condition that is already affected by smoking and other chronic lung disorder like COPD. As smoking habit is not seen in children, the overall impact of COVID-19 may be lessened.
Chronic health conditions like high blood pressure, diabetes, chronic heart, kidney and liver disorders also play a big role in the morbidity and mortality of COVID-19. As these chronic health conditions are rare in children, COVID-19 illness in children may be milder.
Other social measures like school closures, staying at home more than adults, less traveling, less exposure at work, and less exposure to public places may also be playing a role. As adults have more exposure and higher risk than children, severity of the disease and death rate of COVID-19 is probably lower in children.
In any case, it is important to take all the precautions to protect children as they are vulnerable. As the pandemic is still evolving, things may change and age groups affected may also change.
Ludvigsson JF. Systematic review of COVID-19 in children shows milder cases and a better prognosis than adults. Acta Paediatr. 2020 Mar 23. doi: 10.1111/apa.15270.
Dudley JP et al. Disparities in Age-Specific Morbidity and Mortality from SARS-CoV-2 in China and the Republic of Korea. Clin Infect Dis. 2020 Mar 31. pii: ciaa354. doi: 10.1093/cid/ciaa354.
Onder G et al. Case-Fatality Rate and Characteristics of Patients Dying in Relation to COVID-19 in Italy. JAMA. Published online March 23, 2020. doi:10.1001/jama.2020.4683
Zhong hua et al. The epidemiological characteristics of an outbreak of 2019 novel coronavirus diseases (COVID-19) in China. 2020 Feb 17;41(2):145-151. doi: 10.3760/cma.j.issn.0254-6450.2020.02.003.