Impact of Variants, Epidemiological Trends, and Comorbidities on
Hospitalization Rates of Unvaccinated Children in Brazil: A
Retrospective Study (2020-2022)
Abstract
This retrospective study aimed to investigate the impact of the
emergence of new variants and the epidemiological scenario on
hospitalization rates of unvaccinated children (0-12 years) in Brazil.
The study included 1,614 children admitted to a hospital between March
2020 and December 2022, with only 101 (6.3%) of them testing positive
for COVID-19 via RT-PCR. The frequency of COVID-19 cases increased from
7.5% in 2020 to 9.3% in 2022 with the emergence of the Omicron
variant. Children over five years old with comorbidities accounted for
the majority of cases (69% [70/101]). Sickle cell anemia was the
most frequent comorbidity (20%), and flu disease (36% [36/101])
and decompensation of underlying disease (33% [33/101]) were the
main reasons for hospitalization. Co-infection was detected in 11% of
cases, with RSV being the most common viral pathogen (71%). Hospital
readmission occurred in 26% of cases, with a higher frequency in
children over five years old. The death rate was 2.2%, with
comorbidities such as cystic fibrosis and congenital heart disease as
risk factors. These findings emphasize the need to prioritize
vaccination with monovalent Omicron XBB for high-risk groups, including
children over five years old with comorbidities, to mitigate the impact
of new variants and reduce severe disease outcomes.