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.

Telemedicine in the National Immunization Program (Brazil): A promising tool.

The coronavirus disease 2019 pandemic abruptly changed the dynamics of basic health care, with the consequent need for adjustments in essential services. The objective of this study was to evaluate the acceptance and impact of telemedicine at a Reference Center for Special Immunobiologicals (CRIE). Methods: Patients aged 18 years or older who had a medical referral to CRIE and agreed to have a telemedicine consultation were included. After the medical appointments, participants answered a satisfaction survey. Results: From April 2021 to February 2022, 702 telemedicine consultation were conducted. Over 3,380 vaccines were prescribed via telemedicine. Of all the participants who answered the satisfaction questionnaire, 99.8% stated that they would recommend the service to other people. Conclusions: Telemedicine proved to be promising tool for healthcare at CRIE and had good acceptance by users, potentially improving access and extending the reach of the National Immunization Program.

Development and biological evaluation of a new nanotheranostic for tuberculosis.

In this study, we developed, characterized, and tested in vivo polymeric nanoparticle of ethambutol labeled with 99mTc as nanoradiopharmaceutical for early diagnosis of tuberculosis by single-photon emission computed tomography, also as a therapeutic choice. Nanoparticles were developed by double emulsification. All characterization tests were performed, as scanning electron microscopy and dynamic light scattering. The labeling process with 99mTc was performed using the direct labeling process. In vitro and in vivo assays were performed with animals and cells. The results showed that a spherical ethambutol nanoparticle with a size range of 280-300 nm was obtained. The stability test showed that the nanoparticles were well labeled with 99mTc (> 99.1%) and keep labeled over 24 h. The biodistribution assay showed that almost 18% of the nanoparticles were uptake by the lung in infected mice (male C57Bl/6) with Mycobacterium bovis BCG (4 × 105 CFU/cavity), corroborating its use as a nanodrug for tuberculosis imaging. The results for the cell assay corroborate its therapeutical effect. We developed and efficiently tested a new nanodrug that can be used for both imaging and therapy of tuberculosis, acting as a novel nanotheranostic.