The Lancet Regional Health - Americas

BackgroundMass vaccination campaigns started in Brazil on January/2021 with CoronaVac followed by ChAdOx1 nCov-19, and BNT162b2 mRNA vaccines. Target populations initially included vulnerable groups such as people older than 80 years, with comorbidities, of indigenous origin, and healthcare workers. Younger age groups were gradually included. MethodsA national cohort of 66.3 million records was compiled by linking registry-certified COVID-19 vaccination records from the Brazilian National Immun...

Vaccine effectiveness (VE) against emerging SARS-CoV-2 variants is a growing issue. The aim of this work is to evaluate the impact of the COVID-19 additional/booster dose against COVID-19-related symptoms, hospitalization, and death using surveillance data (December 2021-May 2022) from the Italian National Institute of Health (ISS). As of 18 May 2022, for people fully vaccinated with three doses, VE was 87.8% (95% confidence interval (CI): 87.6-88.0), whereas VE decreased from 71.5% (95% CI: 71....

Vaccination is a strategy that confers protection against symptomatic infections and/or development of severe COVID-19. In Brazil, COVID-19 vaccination began in January 2021 and has been performed using vaccines from different manufactures including CoronaVac (Sinovac), ChAdOx1 (Oxford/AstraZeneca) and BNT162b2 (Pfizer/BioNTech). One of the main protective mechanisms triggered by vaccination involves the production of IgG antibodies reactive to the Spike antigen of SARS-CoV-2, the levels of whic...

We hypothesized that in individuals with previous SARS-CoV-2 infection, the first vaccine dose would work as a booster, eliciting a faster and more intense immune response. We herein describe antibody responses to the first and second doses of Gam-COVID-Vac (SPUTNIK V) vaccine in health personnel of Tucuman, Argentina, with previous COVID-19 and compared it with uninfected personnel. Individuals with anti-SARS-CoV-2 titers at baseline showed significantly higher responses to the first dose than ...

IntroductionInformation on vaccine effectiveness and viral loads in a context of novel variants of concern (VOC) emergence is of key importance to inform public health policies. This study aimed to estimate a measure of comparative vaccine effectiveness between Omicron (BA.1) and Delta (B.1.617.2 and sub-lineages) VOC according to vaccination exposure (primary or booster) and time since primary vaccination and to compare cycle threshold (Ct) values between Omicron and Delta VOC infections accord...

BackgroundCase reports of Guillain Barre syndrome (GBS) following the Coronavirus Disease 2019 (COVID-19) vaccines administration have been reported. This study investigated the risk of GBS after vaccination with anti-COVID-19 vaccines (BNT162b2/Tozinameran; mRNA-1273/Elasomeran, ChAdOx1-S and Ad26.COV2-S) in the population aged [≥]12 years in Italy. MethodsWe conducted a self-controlled case series study (SCCS) using national data on COVID-19 vaccination linked to emergency care/hospital di...

Brazils vast geographic and socioeconomic diversity has contributed to heterogeneous responses to the COVID-19 pandemic, particularly regarding vaccine distribution. This ecological study examined inequality in COVID-19 vaccine administration across 5,568 Brazilian municipalities from 2021 to 2023. Vaccination coverage was estimated using the vaccination coefficient, and inequality was assessed via the Gini index. We further analyzed associations between vaccine distribution inequality and socio...

ObjectiveTo compare the population rate of COVID-19 and influenza hospitalizations by age, COVID-19 vaccine status and pandemic phase. DesignObservational retrospective study SettingResidents of British Columbia (population 5.3 million), Canada ParticipantsHospitalized patients due to COVID-19 or historical influenza Main outcome measuresThis population based study in a setting with universal healthcare coverage, used COVID-19 case and hospital data for COVID-19 and influenza. Admissions wer...

We used a test-negative design to estimate the vaccine effectiveness of Ad26.COV2.S (Janssen) against symptomatic COVID-19 and clinical outcomes in Mato-Grosso do Sul, Brazil. We analyzed 11,817 RT-PCR tests. The mean age was 37 (SD=17) years, 2,308 (20%) of individuals more or equal than 50 years and almost two-thirds of the population was Brown/Pardo. Adjusted effectiveness against symptomatic COVID-19 after 28 days of the single dose was 50.9% (95% CI, 35.5-63.0). Adjusted effectiveness again...

As SARS-CoV-2 threatens to overwhelm health systems in Canada, it is imperative that provinces are able to plan and manage an effective and reduced risk response. For this response to be most effective, it must reflect an evidence-based, pan-Canadian response. We designed four different prototypical patients with a combination of common COVID-19 symptoms and opportunities for exposure who were made to self-assess using the 10 provincial COVID-19 self-assessment tools on 1 April. These tools were...

The hospitalization and symptomatic rates of Severe Acute Respiratory Syndrome Coronavirus Disease 2019 (SARS-CoV-2) are key epidemiological parameters affecting risk analyses conducted for the Canadian Armed Forces (CAF) during the Coronavirus Disease-19 (COVID-19) pandemic. As one of the criteria of a variant of concern (VOC) is that it affects disease severity, the authors sought to understand whether the Alpha and Gamma VOCs are significantly different in these two parameters than the origin...

ImportanceAccurate understanding of COVID pandemic during the first viral wave in Canada could help prepare for future epidemic waves. ObjectiveTo track the early course of the pandemic by examining self-reported COVID symptoms over time before testing became widely available. DesignAdults from the nationally representative Angus Reid Forum were randomly invited to complete an online survey in May/June 2020. The study is a part of the Action to Beat Coronavirus antibody testing study. Setting...

BackgroundThe Coronavirus disease 2019 (COVID-19) pandemic has had significant global impact. While public health interventions and universal health insurance has been credited with minimizing transmission rates in Canada relative to neighboring countries, significant morbidity and mortality have occurred nationwide. We sought to determine factors associated with differences in gastrointestinal outcomes in COVID-19 patients at a Canadian hospital. MethodsWe collected data from 192 hospital reco...

IntroductionThe COVID-19 pandemic posed significant challenges, including rehospitalization of patients due to SARS-CoV-2 reinfection, particularly in the context of variants of concern and Brazils COVID-19 vaccination campaign. This study aimed to estimate the rate of rehospitalizations due to reinfection in the municipality of Rio de Janeiro (2020-2022), assess the impact of individual vaccination status, and identify factors associated with this outcome. MethodsCohort study including individ...

ObjectivesTo evaluate the survival of health workers infected by SARS-CoV-2 in the context of the vaccination process against COVID-19 in Peru. MethodsA survival analysis was performed using data from national health databases. Data from people between 18 and 59 years old infected with SARS-CoV-2 as evidenced by molecular or antigenic tests were included. Kaplan Meier graphs were produced to compare the survival of health workers and the rest of the population during 2021 and health workers dur...

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 (SAR...

PurposeIn this study, we examine the joint effects of stunting and socioeconomic status (SES) on COVID-19 serostatus in Brazil and whether these patterns vary by COVID-19 vaccine status. MethodsWe use data from birth through the 7-year follow-up of the Pelotas 2015 birth cohort, including anthropometry, demographics, vaccination status, and COVID-19 antibody test results. We use linear regression models to examine the associations between SES (exposure) and stunting (effect modifier) on COVID-1...

IntroductionCoronavirus disease-19 (COVID-19) has caused a marked increase in all-cause deaths in the United States, mostly among adults aged 65 and older. Because younger adults have far lower infection fatality rates, less attention has been focused on the mortality burden of COVID-19 in this demographic. MethodsWe performed an observational cohort study using public data from the National Center for Health Statistics at the United States Centers for Disease Control and Prevention, and CDC Wo...

BackgroundThe EPICOVID19-RS study conducted 10 population-based surveys in Rio Grande do Sul (Southern Brazil), starting early in the epidemic. The sensitivity of the rapid point-of-care test used in the first eight surveys has been shown to decrease over time after some phases of the study were concluded. The 9th survey used both the rapid test and an enzyme-linked immunosorbent assay (ELISA) test, which has a higher and stable sensitivity. MethodsWe provide a theoretical justification for a c...

BackgroundTo mitigate transmission and reduce the morbidity and mortality, the CDC recommends that individuals aged 65 and older receive a second dose of the 2024-2025 COVID-19 vaccine six months after their first booster dose. However, the optimal dates for biannual boosting are unknown. Geographic variation in infection rates throughout the year make it challenging to intuit the best yearly booster administration date to effectively prevent infection. With rapid waning and strong peaks associa...