Booster dose of six Covid vaccines safe, increases immunity: Study
Latest study looked at safety, immune response, sideeffects of 7 vaccines when used as a third booster jab
NEW DELHI: Six different COVID-19 boosters are safe and elicit strong immune response in people who have previously received a twodose course of AstraZeneca or Pfizer vaccines, according to a study published in The Lancet journal.
Two doses of AstraZeneca and Pfizer vaccines have shown 79 per cent and 90 per cent protection, respectively, against hospitalisation and death after six months in several studies, the researchers said.
However, protection against COVID-19 infection wanes over time, which has driven consideration of boosters to protect the most vulnerable and lessen pressure on health services.
The latest study looked at safety, immune response and side-effects of seven vaccines when used as a third booster jab.
The vaccines studied were AstraZeneca, Pfizer-BioNTech,
Novavax, Janssen, Moderna, Valneva, and Curevac.
"The side effect data show all seven vaccines are safe to use as 3rd doses, with acceptable levels of inflammatory side effects like injection site pain, muscle soreness, fatigue," said Professor Saul Faust, trial lead from the University Hospital Southampton NHS Foundation Trust, UK.
"Whilst all boosted spike protein immunogenicity after two doses of AstraZeneca, only AstraZeneca, Pfizer-BioNTech, Moderna, Novavax, Janssen and Curevac did so after two doses of Pfizer-BioNTech," Faust said.
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 PfizerBioNTech. The trial involved 2,878 participants in good health recruited at 18 UK sites between June 1 and June 30, 2021.
Around half of participants received two doses of AstraZeneca and half two doses of Pfizer.
The control vaccine used was a meningococcal conjugate vaccine (MenACWY).
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.
The vaccines studied were AstraZeneca, Pfizer-BioNTech, Novavax, Janssen, Moderna, Valneva, and Curevac