We investigated vaccine-induced neutralizing antibody titers against the Delta (B.1.617.2) and the Omicron (BA.1 sublineage of B.1.1.529) variants and compared them with the neutralization titers produced against the ancestral A lineage, using authentic SARS-CoV-2 isolates. To characterize SARS-CoV-2-specific adaptive immune responses we analyzed plasma samples from 101 non-hospitalized adult participants who received the BNT162b2 booster dose between 30 July and 27 August 2021, at least 4?weeks after the second dose of CoronaVac. 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 Ionomycin 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 Ionomycin vaccine boosters to combat the impact of emerging variants. Subject terms: Antibodies, Inactivated vaccines BNT162b2 booster vaccination in individuals who had previously received two doses of CoronaVac elevates neutralizing antibodies against the Omicron variant, but titers remain reduced compared with those against the ancestral SARS-CoV-2 virus and the Delta variant. Main The ongoing evolution of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the recent emergence of the Omicron variant raise concerns about its increased transmissibility and vaccine effectiveness. CoronaVac is Ionomycin a two-dose -propiolactone-inactivated, aluminum hydroxide-adjuvanted coronavirus disease 2019 (COVID-19) vaccine. CoronaVac is widely used globally and has been authorized in 48 countries, with 85% and 80% effectiveness against hospital admission and death, respectively1. However, with the emergence of new SARS-CoV-2 variants and the waning immunity of vaccines over time, multiple countries have initiated the use of booster doses2C4. The Dominican Republic was among the first countries to recommend a third booster dose to address potential waning immunity and reduced effectiveness against variants. The Ionomycin Omicron variant contains up to 36 mutations in the spike protein5, rendering many vaccines less effective6,7. The Omicron variant is also highly transmissible, overtaking Delta as the dominant variant in many countries. To assess the potential risk of vaccine immune evasion we assembled a cohort of CoronaVac-vaccinated individuals who had received a heterologous BNT162b2 mRNA Ionomycin vaccine boost. We investigated vaccine-induced neutralizing antibody titers against the Delta (B.1.617.2) and the Omicron (BA.1 sublineage of B.1.1.529) variants and compared them with the neutralization titers produced against the ancestral A lineage, using authentic SARS-CoV-2 isolates. To characterize SARS-CoV-2-specific adaptive immune responses we analyzed plasma samples from 101 non-hospitalized adult participants who received the BNT162b2 booster dose between 30 July and 27 August 2021, at least 4?weeks after the second dose of CoronaVac. Plasma samples were collected longitudinally at Departamento de Investigaciones Biomedicas, Clinica Evangelina Rodriguez, Profamilia, Santo Domingo, Dominican Republic, at baseline (prior to the booster), 7 and 28?days after the booster (third dose), and were analyzed with ELISA and neutralization assays using authentic virus. Data from a previous cohort, composed of healthcare workers (HCWs) from the Yale-New Haven Hospital who received two doses of an mRNA COVID-19 vaccine (mRNA-1273, Moderna or BNT162b2, Pfizer-BioNTech) were used as a reference8. The mean age of the 101 participants from the Dominican Republic (the majority of whom (70%) were female) was 40.4 (s.d. 13.4)?years and the body mass index was 27.6 (s.d. 5.5)?kg?m?2. Cohort demographics, vaccination and infection status are summarized in Extended Data Tables ?Tables11 and ?and22. Extended Data Table 1 Patient data: Dominican Republic SARS-CoV-2-vaccinated cohort Open in a separate window Exact counts for each demographic category are displayed in N cell. Percentages of total, where applicable, are displayed in (%) cell. The mean with accompanying standard deviations for each Rabbit polyclonal to AQP9 measurement are displayed in Mean and SD cells respectively. Extended Data Table 2 Patient data: Yale healthcare worker SARS-CoV-2-vaccinated cohort Open.
We investigated vaccine-induced neutralizing antibody titers against the Delta (B
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