During the COVID-19 pandemic, vaccination played a central role in reducing morbidity and mortality in the country. In general, increased vaccination coverage (VC) was associated with declines in hospitalizations and deaths. However, local and regional disparities can influence vaccine uptake, immune response and disease control. To assess the association between VC against COVID-19 and epidemiological indicators in the municipality of Imperatriz (MA) between 2021 and 2025. Observational, descriptive, retrospective, analytical and quantitative study using secondary data extracted from the National Vaccine Monitor (Vacinômetro Nacional) and the Ministry of Health’s COVID-19 platform in July 2025. VCs of the first dose (1stD) and second dose (2ndD), and annual data on number of cases (NC), deaths (OB), incidence rate (IR) and mortality rate (MR) due to COVID-19 were included. The year 2020 was excluded because vaccination had not yet started. For statistical analysis, Jamovi software was used, applying Pearson (r) and Spearman (ρ) correlation tests, with significance level p < 0.05. There was a negative correlation between year and VCs for 1stD (ρ = -1.000; p = 0.017) and 2ndD (ρ = -1.000; p = 0.017), indicating a progressive decline in vaccine uptake over time. A strong correlation was found between 1stD and 2ndD ( r = 0.999; p < 0.001), suggesting continuity between the steps of the vaccination schedule. NC showed a negative correlation with time ( r = -0.912; p = 0.031), evidencing reduced incidence in the most recent years. A high and significant correlation was also observed between VC and number of deaths (1stD and 2ndD: r = 0.998; p < 0.001) and with MR (1stD: r = 1.000; p < 0.001; 2ndD: r = 0.998; p < 0.001). There is a decline in VC against COVID-19 in Imperatriz (MA), even with continuity of the primary schedule, which may be explained by population disinterest associated with the mistaken perception that, since the pandemic is over, the vaccine is no longer necessary. The positive correlation between vaccination and MR suggests the action of external factors, such as overload of health services in the region. This association may reflect the role of Imperatriz as a regional health hub, receiving severe cases from neighboring municipalities. Other hypotheses should be considered, such as hospital overload, local vaccine effectiveness and adverse events associated with the immunobiologic, which should be investigated in studies with causal designs.
Santana et al. (Sun,) studied this question.