Seroepidemiology of SARS-CoV-2 on a partially vaccinated island in Brazil: Determinants of infection and vaccine response.

Background: A vaccination campaign targeted adults in response to the pandemic in the City of Rio de Janeiro. Objective: We aimed to evaluate the seroprevalence of SARS-CoV-2 antibodies and identify factors associated with seropositivity on vaccinated and unvaccinated residents. Methods: We performed a seroepidemiologic survey in all residents of Paquetá Island, a neighborhood of Rio de Janeiro city, during the COVID-19 vaccine roll-out. Serological tests were performed from June 16 to June 19, 2021, and adjusted seropositivity rates were estimated by age and epidemiological variables. Logistic regression models were used to estimate adjusted ORs for risk factors to SARS-CoV-2 seropositivity in non-vaccinated individuals, and potential determinants of the magnitude of antibody responses in the seropositive population. Results: We included in the study 3,016 residents of Paquetá (83.5% of the island population). The crude seroprevalence of COVID-19 antibodies in our sample was 53.6% (95% CI = 51.0, 56.3). The risk factors for SARS-CoV-2 seropositivity in non-vaccinated individuals were history of confirmed previous COVID-19 infection (OR = 4.74; 95% CI = 3.3, 7.0), being a household contact of a case (OR = 1.93; 95% CI = 1.5, 2.6) and in-person learning (OR = 2.01; 95% CI = 1.4, 3.0). Potential determinants of the magnitude of antibody responses among the seropositive were hybrid immunity, the type of vaccine received, and time since the last vaccine dose. Being vaccinated with Pfizer or AstraZeneca (Beta = 2.2; 95% CI = 1.8, 2.6) determined higher antibody titers than those observed with CoronaVac (Beta = 1.2; 95% CI = 0.9, 1.5). Conclusions: Our study highlights the impact of vaccination on COVID-19 collective immunity even in a highly affected population, showing the difference in antibody titers achieved with different vaccines and how they wane with time, reinforcing how these factors should be considered when estimating effectiveness of a vaccination program at any given time. We also found that hybrid immunity was superior to both infection-induced and vaccine-induced immunity alone, and online learning protected students from COVID-19 exposure.

Seroepidemiology of SARS-CoV-2 on a partially vaccinated island in Brazil: Determinants of infection and vaccine response

Background A vaccination campaign targeted adults in response to the pandemic in the City of Rio de Janeiro. Objective We aimed to evaluate the seroprevalence of SARS-CoV-2 antibodies and identify factors associated with seropositivity on vaccinated and unvaccinated residents. Methods We performed a seroepidemiologic survey in all residents of Paquetá Island, a neighborhood of Rio de Janeiro city, during the COVID-19 vaccine roll-out. Serological tests were performed from June 16 to June 19, 2021, and adjusted seropositivity rates were estimated by age and epidemiological variables. Logistic regression models were used to estimate adjusted ORs for risk factors to SARS-CoV-2 seropositivity in non-vaccinated individuals, and potential determinants of the magnitude of antibody responses in the seropositive population. Results We included in the study 3,016 residents of Paquetá (83.5% of the island population). The crude seroprevalence of COVID-19 antibodies in our sample was 53.6% (95% CI = 51.0, 56.3). The risk factors for SARS-CoV-2 seropositivity in non-vaccinated individuals were history of confirmed previous COVID-19 infection (OR = 4.74;95% CI = 3.3, 7.0), being a household contact of a case (OR = 1.93;95% CI = 1.5, 2.6) and in-person learning (OR = 2.01;95% CI = 1.4, 3.0). Potential determinants of the magnitude of antibody responses among the seropositive were hybrid immunity, the type of vaccine received, and time since the last vaccine dose. Being vaccinated with Pfizer or AstraZeneca (Beta = 2.2;95% CI = 1.8, 2.6) determined higher antibody titers than those observed with CoronaVac (Beta = 1.2;95% CI = 0.9, 1.5). Conclusions Our study highlights the impact of vaccination on COVID-19 collective immunity even in a highly affected population, showing the difference in antibody titers achieved with different vaccines and how they wane with time, reinforcing how these factors should be considered when estimating effectiveness of a vaccination program at any given time. We also found that hybrid immunity was superior to both infection-induced and vaccine-induced immunity alone, and online learning protected students from COVID-19 exposure.

PNAD COVID-19: A powerful new tool for Public Health Surveillance in Brazil

Resumo O Ministério da Saúde declarou em 03 de fevereiro de 2020 estado de emergência em saúde pública de importância nacional em decorrência da pandemia pelo novo coronavírus SARS-CoV-2. Com isso, o IBGE adiou a realização do Censo Demográfico de 2020 e passou a formular uma PNAD COVID-19. O inquérito contou com uma amostra total de 349 mil pessoas em cerca de 200 mil domicílios. Do total da população-residente brasileira, o IBGE estimou em maio/2020 que 24,0 milhões (11,4%) tiveram pelo menos um dos sintomas de síndrome gripal (SG). Desse contingente, 20,2 milhões (84,3% do total dos sintomáticos) não procuraram unidade de saúde. As inovações trazidas para a vigilância em saúde e o pioneirismo do IBGE demonstram ser possível, em um país continental e que vem experimentando diversas epidemias locais em momentos diferentes em seu território, que outros países também desenvolvam inquéritos domiciliares semelhantes, com coleta de dados semanal (referida às semanas epidemiológicas) por telefone de forma inovadora e tempestiva. A PNAD COVID-19 trouxe ainda uma nova tecnologia para o Instituto, resgatando o papel de avaliador externo do Sistema Único de Saúde (SUS). On February 3, 2020, the Brazilian Ministry of Health declared a state of emergency in public health of national relevance due to the pandemic caused by the new coronavirus SARS-CoV-2. As a result, IBGE postponed the 2020 Demographic Census and started to formulate a COVID-19 PNAD. The survey included a total sample of 349 thousand people in about 200 thousand households. Of the total Brazilian resident population, the IBGE estimated in May/2020 that 24.0 million (11.4%) had at least one of the flu-like syndrome symptoms. Of this contingent, 20.2 million (84.3% of all symptomatic patients) did not seek health care. The innovations brought to health surveillance and the IBGE's pioneering spirit show that it is possible, in a continental country that has been experiencing several local epidemics at different times in its territory, that other countries also develop similar household surveys, with weekly data collection (referred to epidemiological weeks) by telephone in an innovative and timely manner. The COVID-19 PNAD also brought new technology to the Institute, reviving its role as an external evaluator of the Unified Health System (SUS).

PNAD COVID-19: A powerful new tool for Public Health Surveillance in Brazil. / PNAD COVID-19: um novo e poderoso instrumento para Vigilância em Saúde no Brasil.

On February 3, 2020, the Brazilian Ministry of Health declared a state of emergency in public health of national relevance due to the pandemic caused by the new coronavirus SARS-CoV-2. As a result, IBGE postponed the 2020 Demographic Census and started to formulate a COVID-19 PNAD. The survey included a total sample of 349 thousand people in about 200 thousand households. Of the total Brazilian resident population, the IBGE estimated in May/2020 that 24.0 million (11.4%) had at least one of the flu-like syndrome symptoms. Of this contingent, 20.2 million (84.3% of all symptomatic patients) did not seek health care. The innovations brought to health surveillance and the IBGE's pioneering spirit show that it is possible, in a continental country that has been experiencing several local epidemics at different times in its territory, that other countries also develop similar household surveys, with weekly data collection (referred to epidemiological weeks) by telephone in an innovative and timely manner. The COVID-19 PNAD also brought new technology to the Institute, reviving its role as an external evaluator of the Unified Health System (SUS).