Health Surveillance and Epidemiological Profile of Severe Acute Respiratory Syndrome due to COVID-19 in Brazil (2020-2024)
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The COVID-19 crisis exposed structural inequalities in Brazil, such as the concentration of healthcare resources in metropolitan areas. Despite the availability of effective vaccines, full immunization coverage was not universal, allowing cases to progress to severe acute respiratory syndrome (SARS). This study aimed to analyse the progression of mild, moderate, and severe cases between January 2020 and December 2024, covering a five-year period, taking into account regional, social, and variant-related differences, vaccination, and factors associated with SARS due to COVID-19 in Brazil. A total of 47,547,814 influenza-like illness (mild and moderate) cases, 2,127,427 SARS cases due to COVID-19, 533,966,291 vaccination records, and data on circulating variants were collected. Among the SARS cases, 1,171,801 were confirmed by PCR; 777,672 patients recovered, and 394,129 died, resulting in a case fatality rate of 33.63%. Brazil experienced three major waves of SARS due to COVID-19, with the second wave being the deadliest across all regions. The Gamma and Omicron variants were the most persistent and impactful. The transition between variants influenced the regional dynamics of the pandemic, although little variation was observed in the proportion of circulating variants across regions. The study highlights the importance of continuous monitoring, genomic surveillance, and vaccination coverage to anticipate and mitigate future pandemic waves.
WHAT WAS ALREADY KNOWN?
Variants influence COVID-19 severity: Variants such as Delta and Gamma were already associated with increased transmissibility and lethality.
Vaccination has a protective role against severe forms of the disease: Previous data showed reduced mortality with vaccines, especially after completing the primary series.
Regional inequalities impact outcomes: Regions with lower healthcare infrastructure, especially in the North and Northeast, face higher fatality rates.
WHAT IS NEW?
Three major waves of SARS due to COVID-19, with marked differences by region and variant: The second wave was the deadliest, and Omicron, though less pathogenic, had widespread circulation and three distinct peaks.
Direct impact of sociodemographic and economic factors on outcomes: Lethality was higher among illiterate individuals, Black and Brown populations, and rural residents.
Robust effect of booster vaccination on survival: Individuals with a first or second booster were up to 60% less likely to die and had four times higher survival at 40 days compared to unvaccinated individuals.
