Health and Fitness

Effectiveness of CoronaVac, AZD1222, and BNT162b2 vaccine boosters

In a current examine revealed in The Lancet Global Health journal, the researchers assessed the efficacy of homologous and heterologous booster doses of extreme acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines.   

Study: Effectiveness of homologous and heterologous booster doses for an inactivated SARS-CoV-2 vaccine: a large-scale prospective cohort study. Image Credit: Wachiwit/Shutterstock
Study: Effectiveness of homologous and heterologous booster doses for an inactivated SARS-CoV-2 vaccine: a large-scale potential cohort examine. Image Credit: Wachiwit/Shutterstock

Coronavirus illness 2019 (COVID-19) vaccines have proved instrumental in curbing the mortality and morbidity brought about globally by the pandemic. However, numerous research have reported waning vaccine effectiveness towards SARS-CoV-2 infections.

About the examine

In the current examine, the researchers investigated the effectiveness of CoronaVac, AZD1222, and BNT162b2 vaccine booster doses towards COVID-19 infections, associated hospitalizations, intensive care unit (ICU) admissions, and deaths in individuals vaccinated with the first collection of CoronaVac.

The crew used individual-level data obtained from an observational, potential, national-level inhabitants from the Fondo Nacional de Salud (FONASA). Participants eligible for the examine have been people aged 16 years and above, who had an affiliation with FONASA, and have been vaccinated with both the CoronaVac, AZD1222, or the BNT162b2 SARS-CoV-2 vaccines between 2 February 2021 and the tip date of examine of 10 November 2021, or had not been vaccinated in the course of the specified interval.

In Chile, people above 55 years may obtain a booster dose of AZD1222, and people below 55 years may obtain one BNT162b2 booster dose. The researchers analyzed the efficacy of homologous in addition to heterologous vaccine booster doses by classifying the examine contributors into the next cohorts: (1) unvaccinated people; (2) people vaccinated with two doses of CoronaVac vaccine 14 days or extra after the receipt of the second dose and earlier than the third dose was administered, and (3) people vaccinated with three vaccine doses 14 days or extra after receiving the third vaccine dose of both the homologous collection of CoronaVac or a heterologous dose with both the BNT162b2 or the AZD1222.

The crew primarily analyzed the effectiveness of booster vaccine doses in CoronaVac-vaccinated individuals versus the unvaccinated individuals. They additionally in contrast the effectiveness of the homologous and the heterologous booster vaccines compared to the CoronaVac major collection of two vaccine doses.

The major outcomes of the examine included the variety of confirmed COVID-19 instances, associated hospitalizations, ICU admissions, and deaths. The crew additionally thought-about the time between the start of the examine to the date of COVID-19 symptom onset because the endpoint for the 4 major outcomes. COVID-19 instances have been outlined as laboratory-confirmed SARS-CoV-2 infections and associated deaths accompanied by code U07.1 within the International Classification of Diseases (ICD)-10-CM.   


The examine outcomes confirmed that the evaluation cohort comprised 11,806,589 people aged 16 years and above, amongst which a complete of 11,174,257 people have been eligible. As of 10 November 2021, virtually 10,71,998 people have been unvaccinated, and 678,331 have been vaccinated with one dose of both the BNT162b2, CoronaVac, or the AZD1222 vaccine, whereas 94,23,928 had acquired two doses of both of the three COVID-19 vaccines. Among vaccinated individuals with the first collection of COVID-19 vaccines, 74.5% acquired two doses of CoronaVac. Among these, a complete of 186,946 have been vaccinated with the third dose of CoronaVac, 2,019,260 with a BNT162b2 booster dose, and 1,921,340 with an AZD1222 booster dose.

The crew additionally discovered a big distinction within the incidence of COVID-19 infections with respect to the vaccinated standing of the contributors, gender, age, current comorbidities, nation of origin, residential space, and revenue. A complete of 4,127,546 booster doses have been administered after major vaccination with two doses of the CoronaVac vaccine. Almost 95% of the booster doses acquired have been heterologous, together with 46.5% who acquired an AZD1222 booster dose and 48.9% who acquired a BNT162b2 booster dose, whereas 4.5% acquired a homologous booster dose with CoronaVac. 

After major vaccination with CoronaVac, the vaccine effectiveness of the CoronaVac booster dose was 63.8% towards an infection, 59.3% towards associated hospitalization, 71.2% towards ICU admission, and 62.7% towards loss of life. The vaccine effectiveness of the BNT162b2 and AZD1222 booster doses have been 93.5% and 88.4% towards an infection, 86.6% and 93.0% towards associated hospitalization, 84.1% and 95.9% towards ICU admission, and 90.7% and 94.7% towards loss of life, respectively.    


Overall, the examine findings confirmed {that a} homologous or a heterologous COVID-19 booster vaccine dose in people vaccinated with the first collection of the CoronaVac vaccine induced a big degree of safety towards COVID-19, associated hospitalization, and loss of life.  

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