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

## TL;DR

The study finds that the omicron variant causes milder symptoms in young children in Brazil compared to other variants like delta and the original strain.

## Contribution

The study provides new insights into the severity of different SARS-CoV-2 variants in children under 2 years old in Brazil.

## Key findings

- Omicron infection is associated with milder symptoms and lower risk of death compared to the original and delta variants.
- Children aged 1-6 months are most affected, but lack vaccination coverage.
- Gamma and delta variants are linked to more severe respiratory symptoms.

## Abstract

•The original variant was responsible for most of the cases that evolved with death, omicron seems to be responsible for milder symptoms when compared to delta.•Children between 1‒6-months of age account for most of the cases, which concerns since there is no vaccination coverage.

The original variant was responsible for most of the cases that evolved with death, omicron seems to be responsible for milder symptoms when compared to delta.

Children between 1‒6-months of age account for most of the cases, which concerns since there is no vaccination coverage.

To analyze whether there is a significant difference in the virulence, symptoms, and outcomes of different Coronavirus Disease 2019 (COVID-19) variants in children under 2-years of age. We collected data from the Sistema de Informação de Vigilância Epidemiológica da Gripe, a nationwide Brazilian database on severe acute respiratory syndrome. The patients were classified according to four variants of concern: wild-type, gamma, delta, and omicron. The wild-type variant was defined as the baseline. A total of 11,153 patients were analyzed. The risk of presenting dyspnea (adjusted Odds Ratio[Aor = 1.20], 95 % Confidence Interval [95 % CI 1.07–1.34]) was higher in patients with gamma infection. Respiratory discomfort was more likely to be present for the omicron (Aor = 1.29, 95 % CI 1.15–1.43) and gamma (aOR = 1.26, 95 % CI 1.13–1.41) infections. Desaturation was more likely to be present for the omicron (aOR = 1.67, 95 % CI 1.50–1.86), gamma (aOR = 1.16, 95 % CI 1.43–1.79), and delta (aOR 1.41, CI 95 % 1.18–1.68) infections. Infection by the omicron variant was a protective factor for intubation (aOR = 0.78, 95 % CI 0.67–0.91) and death (aOR = 0.43, 95 % CI 0.35–0.53). Additionally, delta infection was a protective factor against death (aOR = 0.60, 95 % CI 0.43–0.85). The wild-type variant was responsible for most of the cases that evolved with death. Omicron appears to be responsible for milder symptoms than delta. Children between 1 and 6 months of age account for most cases, which is a concern because there is no vaccination coverage.