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Booster dose of 6 Covid-19 vaccines safe, increases immunity: Lancet

Booster dose of 6 Covid-19 vaccines safe, increases immunity: Lancet

The booster dose of six Covid-19 vaccines is safe and increases strong immune response, according to a study published in The Lancet journal. The six vaccines whose booster doses have shown a strong immune response include AstraZeneca, Pfizer-BioNTech, Novavax, Janssen, Moderna, Valneva, and Curevac. According to the Lancet study, two doses of AstraZeneca and Pfizer vaccines have shown 79% and 90% protection, respectively, against hospitalisation and death after six months. The latest study looked at the safety, immune response, and side-effects of seven vaccines when used as a third booster jab. As per the study the booster dose beneficiary might face side effects like injection site pain, muscle soreness, fatigue, said Professor Saul Faust, trial lead from the University Hospital Southampton NHS Foundation Trust, UK. The researchers noted that these results relate only to these vaccines as boosters to the two primary vaccinations, and to the immune response they drive at 28 days. Further work will generate data at three months and one year after people have received their boosters, which will provide insights into their impact on long-term protection and immunological memory, they said. A randomised, phase 2 trial of the seven booster vaccines was conducted, with the third doses given 10-12 weeks after initial two-dose courses of AstraZeneca or Pfizer-BioNTech. The trial involved 2,878 participants in good health recruited at 18 UK sites between June 1 and June 30, 2021. Around half of the participants received two doses of AstraZeneca and half two doses of Pfizer. Participants were aged 30 years or older, with approximately half aged 70 years or older. Thirteen experimental and control arms of the trial were split into three participant groups, with six sites per group. Group A received Novavax, half dose Novavax, AstraZeneca, or a control. Group B received Pfizer, Valneva, half dose Valneva, Janssen, or a control. Group C received Moderna, Curevac, which was withdrawn from further clinical development in October 2021, half dose Pfizer, or a control. Primary outcomes were adverse effects seven days after receiving a booster, and levels of antibodies targeting the spike protein on the surface of COVID-19 virus cells – which enables them to enter human cells – after 28 days, compared to controls. Secondary outcomes included the response of T cells -- which play a key role in the immune response to viral infection and seem important in controlling disease severity -- to wild type, Alpha, Beta, and Delta variants. Both antibody-mediated immunity and T-cell response are known to be important in vaccine effectiveness, the researchers said. Increases in anti-spike protein antibody levels after 28 days varied across the vaccines. After two doses of AstraZeneca, these ranged from 1.8 times higher to 32.3 times higher according to the booster vaccine used. After two doses of Pfizer, the range was 1.3 times higher to 11.5 times higher. Significant T-cell responses were reported in several combinations, the researchers said. At 28 days, all booster results were similar for participants aged 30-69 years and those aged 70 years or older, they said. (With PTI inputs) Download.

science 2021-12-03 Livemint