Coronavirus disease 2019 infection severity among different variants in children under 2-years old in Brazil

Area of Science:

• Pediatrics
• Infectious Diseases
• Virology

Background:

• Severe acute respiratory syndrome (SARS) in children under two years old presents unique challenges.
• Understanding the differential impact of Coronavirus Disease 2019 (COVID-19) variants is crucial for pediatric public health.
• The emergence of new variants necessitates ongoing surveillance of their clinical manifestations in vulnerable populations.

Purpose of the Study:

• To compare the virulence, symptoms, and outcomes of different COVID-19 variants (wild-type, Gamma, Delta, Omicron) in children under two years of age.
• To identify specific variant-associated risks for severe respiratory symptoms and adverse outcomes.
• To evaluate the protective effects of certain variants against critical illness and mortality in this age group.

Main Methods:

• Analysis of a nationwide Brazilian database (Sistema de Informação de Vigilância Epidemiológica da Gripe) for severe acute respiratory syndrome cases.
• Classification of pediatric patients (under 2 years) based on COVID-19 variant: wild-type, Gamma, Delta, and Omicron.
• Statistical analysis using adjusted Odds Ratios (aOR) and 95% Confidence Intervals (95% CI) to assess variant-specific risks and protective factors.

Main Results:

• Gamma variant infection was linked to a higher risk of dyspnea (aOR=1.20) and respiratory discomfort (aOR=1.26).
• Omicron variant infection increased the likelihood of respiratory discomfort (aOR=1.29) and desaturation (aOR=1.67). Delta variant also increased desaturation risk (aOR=1.41).
• Omicron infection was protective against intubation (aOR=0.78) and death (aOR=0.43). Delta infection was protective against death (aOR=0.60). Wild-type was associated with the highest mortality.

Conclusions:

• COVID-19 variants exhibit distinct clinical profiles in children under two, with Gamma and Omicron associated with increased respiratory symptoms.
• Omicron and Delta variants demonstrated a protective effect against severe outcomes like intubation and death compared to the wild-type.
• Young infants (1-6 months) represent a high-risk group due to lack of vaccination coverage and higher case incidence, warranting focused public health interventions.