Scholarlink

Background <p>CoronaVac was the first COVID-19 vaccine deployed at scale in Brazil, yet evidence on its real-world impact and the durability of immune responses in small municipalities remains limited. Understanding vaccine performance in diverse settings is essential for informing public health strategies. This study aimed to evaluate the seroprevalence and durability of the immune response and investigate the real-world impact of the CoronaVac vaccine in adults from a small municipality in Northeast Brazil.</p> Methods <p>This is an analytical, observational, population-based study comprising a cross-sectional seroepidemiological survey and a retrospective cohort analysis conducted in Guaramiranga, Ceará, between September 2021 and August 2022. A total of 1,714 individuals who had received two doses of CoronaVac were included. Serological survey (anti-SARS-CoV-2 IgG), molecular testing (RT‒PCR), and linkage of official vaccinations and notification records were performed. The analyses included Fisher’s Exact Test for categorical comparisons and Poisson regression with robust variance to estimate prevalence ratios.</p> Results <p>The seroprevalence of neutralizing IgG antibodies was 83.1% (95% CI: 79.7–86.0). Seropositivity showed a significant temporal decline, decreasing from 94.3% (≤ 180 days post-vaccination) to 79.4% (181–270 days post-vaccination) (<i>p</i> = 0.0012). RT‒PCR positivity was 15.3% (95% CI: 12.8–18.2%), increasing to 29.0% 270 days after the second dose (<i>p</i> = 0.0006). In multivariable Poisson regression, time since D2 (PR = 0.9987; <i>p</i> &lt; 0.001), age (PR = 0.9924; <i>p</i> &lt; 0.001), and male sex (PR = 0.9176; <i>p</i> = 0.018) were associated with lower seropositivity. A total of 116 symptomatic cases and 2 severe cases (0.117%) were confirmed, corresponding to an observed incidence of severe disease of 117 per 100,000 person-years (95% CI: 14–422).</p> Conclusions <p>This population-based surveillance study demonstrates that universal CoronaVac vaccination was followed by a robust initial humoral immune response, which subsequently declined over time. The observed low incidence of severe disease in this fully vaccinated population is consistent with protection against severe outcomes. These findings reinforce the need for booster doses and ongoing epidemiological surveillance in small municipalities.</p> Clinical trial number <p>Not applicable.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Seroprevalence, immune response dynamics, and incidence of COVID-19 after CoronaVac vaccination in a fully vaccinated small municipality in Northeast Brazil: a population-based surveillance study

  • 期刊论文

  • 出版模式：

    开放获取

  • 发表日期：

    2026年3月13日

查看全文
  • Lourrany Borges Costa,
  • Francisca Kalline de Almeida Barreto,
  • Patrícia Pereira Lima Barbosa,
  • Magda Moura de Almeida,
  • Antonia Luciana Souza Bekman,
  • Silvana Soares de Souza,
  • Ana Carolina Barjud Marques Máximo,
  • Debora Bezerra Silva,
  • Carlos Henrique Alencar,
  • Luciano Pamplona de Góes Cavalcanti

摘要

Background

CoronaVac was the first COVID-19 vaccine deployed at scale in Brazil, yet evidence on its real-world impact and the durability of immune responses in small municipalities remains limited. Understanding vaccine performance in diverse settings is essential for informing public health strategies. This study aimed to evaluate the seroprevalence and durability of the immune response and investigate the real-world impact of the CoronaVac vaccine in adults from a small municipality in Northeast Brazil.

Methods

This is an analytical, observational, population-based study comprising a cross-sectional seroepidemiological survey and a retrospective cohort analysis conducted in Guaramiranga, Ceará, between September 2021 and August 2022. A total of 1,714 individuals who had received two doses of CoronaVac were included. Serological survey (anti-SARS-CoV-2 IgG), molecular testing (RT‒PCR), and linkage of official vaccinations and notification records were performed. The analyses included Fisher’s Exact Test for categorical comparisons and Poisson regression with robust variance to estimate prevalence ratios.

Results

The seroprevalence of neutralizing IgG antibodies was 83.1% (95% CI: 79.7–86.0). Seropositivity showed a significant temporal decline, decreasing from 94.3% (≤ 180 days post-vaccination) to 79.4% (181–270 days post-vaccination) (p = 0.0012). RT‒PCR positivity was 15.3% (95% CI: 12.8–18.2%), increasing to 29.0% 270 days after the second dose (p = 0.0006). In multivariable Poisson regression, time since D2 (PR = 0.9987; p < 0.001), age (PR = 0.9924; p < 0.001), and male sex (PR = 0.9176; p = 0.018) were associated with lower seropositivity. A total of 116 symptomatic cases and 2 severe cases (0.117%) were confirmed, corresponding to an observed incidence of severe disease of 117 per 100,000 person-years (95% CI: 14–422).

Conclusions

This population-based surveillance study demonstrates that universal CoronaVac vaccination was followed by a robust initial humoral immune response, which subsequently declined over time. The observed low incidence of severe disease in this fully vaccinated population is consistent with protection against severe outcomes. These findings reinforce the need for booster doses and ongoing epidemiological surveillance in small municipalities.

Clinical trial number

Not applicable.