Morbidity, Mortality and Immunization in Severe COVID-19 Among the Elderly in Brazil: A Five-Year Perspective

The COVID-19 pandemic underscored longstanding vulnerabilities within Brazils healthcare system, particularly affecting the elderly population in underserved regions. Although infection can affect individuals across all age groups, the elderly population is particularly susceptible to severe outcomes due to aging-related factors. Despite the availability of effective vaccines, full immunization coverage was not achieved, allowing the progression of cases to severe acute respiratory syndrome (SARS). This study aimed to analyse the evolution of severe COVID-19 cases in parallel with mild and moderate cases among the Brazilian elderly population between January 2020 and December 2024, spanning five years, while considering regional and social differences, circulating variants, vaccination, and factors associated with COVID-19-related SARS in Brazil. A total of 15,609 cases of influenza-like illness (mild and moderate) and 580,818 PCR-confirmed cases were recorded, of which 304,341 resulted in recovery and 276,477 in death, with a case fatality rate of 47.60%. Brazil experienced three waves of COVID-19-related SARS, with the second wave being the most lethal 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?O_LIElderly individuals are more vulnerable to COVID-19: Previous studies had already shown that aging and the presence of comorbidities increased the severity of COVID-19 in this group. C_LIO_LIRegional inequalities influence outcomes: Regions with lower Human Development Index (HDI), limited access to healthcare, and greater social vulnerability presented worse mortality indicators. C_LIO_LIVaccination reduces mortality: It was already known that complete vaccination, especially with booster doses, significantly reduced the severity of COVID-19. C_LI WHAT IS NEW?O_LIMore detailed epidemiological profile by region and year: The study traces the pattern of lethality over a five-year period (2020-2024), revealing significant fluctuations across regions, age groups, educational levels, ethnicities, and geographic zones. C_LIO_LIHigh impact of multimorbidity: The article shows that elderly individuals with three or more comorbidities had the lowest survival rates and the highest risk of death, regardless of their vaccination status. C_LIO_LIClear protective effect of booster doses: The Kaplan-Meier survival analysis demonstrated that only individuals who received a first and/or second booster showed a significant increase in median survival time. C_LI O_FIG O_LINKSMALLFIG WIDTH=143 HEIGHT=200 SRC="FIGDIR/small/25326813v2_ufig1.gif" ALT="Figure 1"> View larger version (52K): org.highwire.dtl.DTLVardef@1b8dba5org.highwire.dtl.DTLVardef@15c60c8org.highwire.dtl.DTLVardef@1d62ac4org.highwire.dtl.DTLVardef@191c88c_HPS_FORMAT_FIGEXP M_FIG C_FIG