ABSTRACT
The recent emergence of the SARS-CoV-2 Omicron variant is raising concerns because of its increased transmissibility and by its numerous spike mutations with potential to evade neutralizing antibodies elicited by COVID-19 vaccines. The Dominican Republic was among the first countries in recommending the administration of a third dose COVID-19 vaccine to address potential waning immunity and reduced effectiveness against variants. Here, we evaluated the effects of a heterologous BNT162b2 mRNA vaccine booster on the humoral immunity of participants that had received a two-dose regimen of CoronaVac, an inactivated vaccine used globally. We found that heterologous CoronaVac prime followed by BNT162b2 booster regimen induces elevated virus-specific antibody levels and potent neutralization activity against the ancestral virus and Delta variant, resembling the titers obtained after two doses of mRNA vaccines. While neutralization of Omicron was undetectable in participants that had received a two-dose regimen of CoronaVac vaccine, BNT162b2 booster resulted in a 1.4-fold increase in neutralization activity against Omicron, compared to two-dose mRNA vaccine. Despite this increase, neutralizing antibody titers were reduced by 6.3-fold and 2.7-fold for Omicron compared to ancestral and Delta variant, respectively. Surprisingly, previous SARS-CoV-2 infection did not affect the neutralizing titers for Omicron in participants that received the heterologous regimen. Our findings have immediate implications for multiples countries that previously used a two-dose regimen of CoronaVac and reinforce the notion 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.
Subject(s)
COVID-19ABSTRACT
Objectives: The primary objective is to determine the effect of a daily dose of ivermectin administered in three consecutive days to non-severe COVID-19 patients with no more than 96 hours of symptoms, on the detection of SARS-CoV-2 RNA by PCR from nasopharyngeal swabs at day seven post-treatment initiation.The secondary objectives are:1. To assess the efficacy of ivermectin to reduce the SARS-CoV-2 viral load in the nasopharyngeal swab on days 4, 7, 14 and 21 post-treatment initiation2. To assess the efficacy of ivermectin on the improvement of symptoms3. To assess the proportion of seroconversions at day 214. To assess the safety of ivermectin at the proposed dose5. To determine the magnitude of the immune response against SARS-CoV-26. To assess correlation of the presence of intestinal helminths on participants on baseline and day 14 with COVID-19 progression and treatment. Trial design: SAINT PERU is a triple-blinded, randomized, placebo-controlled trial with two parallel arms to evaluate the efficacy of ivermectin in negativizing nasopharyngeal PCR in patients with SARS-CoV-2 infection. Participants: The trial is conducted in two national hospitals in Lima-Peru. The study population is patients with a positive PCR test for SARS-CoV-2 in a nasopharyngeal specimen, symptomatic for 96 hours or less, with non-severe COVID-19 disease at baseline, regardless of the presence of risk factors for progression to severity. The study will not include pregnant women or minors (17 years old or younger).
Subject(s)
COVID-19ABSTRACT
The SARS-CoV-2 was first identified in the city of Wuhan, China, in late 2019. Since then, the disease caused by this new coronavirus, COVID-19, represents a growing threat to human health. SARS-CoV-2 is an enveloped single-stranded RNA virus classified in the subfamily Coronavirinae, genus Belacoronavirus. The homology of genomes suggests that bats might be the original host of the virus, and pangolins the intermediate host. The viral glycoprotein S is a crucial target for the development of vaccines, therapeutic targets, and diagnostic tests. This protein facilitates viral entry into target cells and determines host tropism.