Population-Level Effectiveness of an Inactivated Whole-Virion COVID-19 Vaccine: A Test Negative Case-Control Study in the Dominican Republic.

Background: A continuing nationwide vaccination campaign began in the Dominican Republic on February 16, 2021 to prevent severe consequences of acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Estimates of vaccine effectiveness under real-world conditions are needed to support policy decision making and inform further vaccine selection. Methods: We conducted a test-negative case-control study to assess the real-world effectiveness of nationwide coronavirus disease 2019 (COVID-19) vaccination program using an inactivated vaccine (CoronaVac) on preventing symptomatic SARS-CoV-2 infections and hospitalizations from August to November 2021 in the Dominican Republic. Participants were recruited from 10 hospitals in 5 provinces to estimate the effectiveness of full immunization (≥14 days after receipt of the second dose) and partial immunization (otherwise with at least 1 dose ≥14 days after receipt of the first dose). Results: Of 1078 adult participants seeking medical care for COVID-19-related symptoms, 395 (36.6%) had positive polymerase chain reaction (PCR) tests for SARS-CoV-2; 142 (13.2%) were hospitalized during 15 days of follow up, including 91 (23%) among 395 PCR-positive and 51 (7.5%) among 683 PCR-negative participants. Full vaccination was associated with 31% lower odds of symptomatic infection (odds ratio [OR], 0.69; 95% confidence interval [CI], 0.52-0.93) and partial vaccination was associated with 49% lower odds (OR, 0.51; CI, 0.30-0.86). Among 395 PCR-positive participants, full vaccination reduced the odds of COVID-19-related hospitalization by 85% (OR, 0.15; 95% CI, 0.08-0.25) and partial vaccination reduced it by 75% (OR, 0.25; 95% CI, 0.08-0.80); full vaccination was associated with reduced use of assisted ventilation by 73% (OR, 0.27; 95% CI, 0.15-0.49). Conclusions: Given the ancestral and delta viral variants circulating during this study period, our results suggest that the inactivated COVID-19 vaccine offered moderate protection against symptomatic SARS-CoV-2 infections and high protection against COVID-19-related hospitalizations and assisted ventilation. This is reassuring given that, as of August 2022, an estimated 2.6 billion inactivated CoronaVac vaccine doses had been administered worldwide. This vaccine will become a basis for developing multivalent vaccine against the currently circulating omicron variant.

Age-dependent impairment in antibody responses elicited by a homologous CoronaVac booster dose.

The emergence of the SARS-CoV-2 Omicron sublineages resulted in increased transmission rates and reduced protection from vaccines. To counteract these effects, multiple booster strategies were used in different countries, although data comparing their efficiency in improving protective immunity remain sparse, especially among vulnerable populations, including older adults. The inactivated CoronaVac vaccine was among the most widely distributed vaccine worldwide and was essential in the early control of SARS-CoV-2-related hospitalizations and deaths. However, it is not well understood whether homologous versus heterologous booster doses in those fully vaccinated with CoronaVac induce distinct humoral responses or whether these responses vary across age groups. We analyzed plasma antibody responses from CoronaVac-vaccinated younger or older individuals who received a homologous CoronaVac or heterologous BNT162b2 or ChAdOx1 booster vaccine. All three evaluated boosters resulted in increased virus-specific IgG titers 28 days after the booster dose. However, we found that both IgG titers against SARS-CoV-2 Spike or RBD and neutralization titers against Omicron sublineages were substantially reduced in participants who received homologous CoronaVac compared with the heterologous BNT162b2 or ChAdOx1 booster. This effect was specifically prominent in recipients >50 years of age. In this group, the CoronaVac booster induced low virus-specific IgG titers and failed to elevate neutralization titers against any Omicron sublineage. Our results point to the notable inefficiency of CoronaVac immunization and boosting in mounting protective antiviral humoral immunity, particularly among older adults, during the Omicron wave. These observations also point to benefits of heterologous regimens in high-risk populations fully vaccinated with CoronaVac.

Strengthening research ethics governance and regulatory oversight in Central America and the Dominican Republic in response to the COVID-19 pandemic: a qualitative study.

BACKGROUND: Good governance and regulatory supervision are required to conduct research in an international public health emergency context and to ensure compliance with ethical standards. The "Strengthening research ethics governance and regulatory oversight in Central America and the Dominican Republic in response to the COVID-19 pandemic" study is a regional effort in which research ethics stakeholders participated in addressing research ethics governance and preparedness response challenges to the COVID-19 pandemic in Central America and the Dominican Republic. METHODS: A qualitative action research study was conducted following a participatory approach. Research ethics stakeholders in Central America and the Dominican Republic were mapped; a regional webinar and three virtual workshops were conducted discussing research ethics governance, ethics review and collaborative research practice during the pandemic. A roundtable session presented results and obtained feedback on a draft of a policy to strengthen regional research ethics governance. RESULTS: Countries across Central America and the Dominican Republic are at different stages in their development of research ethics systems. Countries with more established systems before COVID-19 were better organized and prepared to respond. This finding argues against improvisation and supports further work on strengthening governance of research ethics systems. Community engagement in research ethics public policy-making is practically absent in the region. Research and research ethics collaboration schemes are lacking amongst the countries; however, there are incipient initiatives in the region, such as the Central America and Caribbean Network of Research Ethics Committees. A policy brief with recommendations on how to advance towards strengthening the governance of research ethics systems was prepared and submitted to the Central American Integration System for analysis and possible approval. CONCLUSION: National research ethics systems in Central America and the Dominican Republic were unprepared to respond to the COVID-19 pandemic with respect to research oversight and effective collaboration. In most cases, national research ethics systems were found to be weak, and regional research collaboration was practically absent. To promote collaboration, a joint strategy needs to be developed with a regional vision towards sharing knowledge and best practices.

No evidence of fetal defects or anti-syncytin-1 antibody induction following COVID-19 mRNA vaccination.

The impact of Coronavirus Disease 2019 (COVID-19) mRNA vaccination on pregnancy and fertility has become a major topic of public interest. We investigated 2 of the most widely propagated claims to determine (1) whether COVID-19 mRNA vaccination of mice during early pregnancy is associated with an increased incidence of birth defects or growth abnormalities; and (2) whether COVID-19 mRNA-vaccinated human volunteers exhibit elevated levels of antibodies to the human placental protein syncytin-1. Using a mouse model, we found that intramuscular COVID-19 mRNA vaccination during early pregnancy at gestational age E7.5 did not lead to differences in fetal size by crown-rump length or weight at term, nor did we observe any gross birth defects. In contrast, injection of the TLR3 agonist and double-stranded RNA mimic polyinosinic-polycytidylic acid, or poly(I:C), impacted growth in utero leading to reduced fetal size. No overt maternal illness following either vaccination or poly(I:C) exposure was observed. We also found that term fetuses from these murine pregnancies vaccinated prior to the formation of the definitive placenta exhibit high circulating levels of anti-spike and anti-receptor-binding domain (anti-RBD) antibodies to Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) consistent with maternal antibody status, indicating transplacental transfer in the later stages of pregnancy after early immunization. Finally, we did not detect increased levels of circulating anti-syncytin-1 antibodies in a cohort of COVID-19 vaccinated adults compared to unvaccinated adults by ELISA. Our findings contradict popular claims associating COVID-19 mRNA vaccination with infertility and adverse neonatal outcomes.

Neutralizing antibodies against the SARS-CoV-2 Delta and Omicron variants following heterologous CoronaVac plus BNT162b2 booster vaccination.

The recent emergence of the SARS-CoV-2 Omicron variant is raising concerns because of its increased transmissibility and its numerous spike mutations, which have the potential to evade neutralizing antibodies elicited by COVID-19 vaccines. Here we evaluated the effects of a heterologous BNT162b2 mRNA vaccine booster on the humoral immunity of participants who had received a two-dose regimen of CoronaVac, an inactivated vaccine used globally. We found that a heterologous CoronaVac prime vaccination of two doses followed by a BNT162b2 booster induces elevated virus-specific antibody levels and potent neutralization activity against the ancestral virus and the Delta variant, resembling the titers obtained after two doses of mRNA vaccines. Although neutralization of Omicron was undetectable in participants who had received a two-dose regimen of CoronaVac, the BNT162b2 booster resulted in a 1.4-fold increase in neutralization activity against Omicron compared with the two-dose mRNA vaccine. Despite this increase, neutralizing antibody titers were reduced by 7.1-fold and 3.6-fold for Omicron compared with the ancestral strain and the Delta variant, respectively. These findings have immediate implications for multiple countries that previously used a CoronaVac regimen and reinforce the idea that the Omicron variant is associated with immune escape from vaccines or infection-induced immunity, highlighting the global need for vaccine boosters to combat the impact of emerging variants.

Nuevo coronavirus 2019-ncov: impacto en salud global

Se trata de una revisión sistemática de una selección de artículos publicados en diferentes fuentes de información, post aparición del primer caso de 2019-nCoV en China, que incluye la infor-mación disponible a febrero 2 del año 2020 sobre diferentes aspectos clínico-epidemiológicos de la epidemia. Se incluye también un análisis comparativo de la forma de transmisión, origen, mortalidad, período de incubación y el número reproductivo básico (R0) o la velocidad con que una enfermedad puede propagarse en una población, de este nuevo coronavirus (2019-nCoV), con la evidencia disponible de estos parámetros para el SARS-CoV y el MERS-CoV, al 2 de febrero del año 2020. Se concluye recomendando la creación de unidades de salud global, lo cual podría favorecer que el sistema de salud perpetúe su impacto en los indicadores de salud de entidades de mayor prevalencia y de comportamiento endémico, mientras que, dichas unidades, orienten los esfuerzos a la implementación efectiva de las medidas de contención y prevención de brotes epidémicos en puertos de entrada y puntos estratégicos de una nación en particular, así como también mejorar la interconexión con otras unidades de similar envergadura y objetivos, en un principio, a nivel regional, pero, como fin último, a nivel global.