Six vaccines safe as boosters, finds UK study

Our Bureau | | Updated on: Dec 03, 2021
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They create strong immune response in those who have taken 2 doses of AZ, Pfizer

As India debates the need for vaccine booster shots, a trial in the UK has found that six different Covid vaccines were safe as boosters and they created a strong immune response in people who have taken two doses of the OxfordUniversity-AstraZeneca or Pfizer-BioNTech vaccines, respectively.

“Two doses of ChAd (OxfordUniversity-AstraZeneca) and BNT (Pfizer-BioNTech) have shown 79 per cent and 90 per cent protection, respectively, against hospitalisation and death after six months in several studies.

However, protection against Covid infection wanes over time. That has driven consideration of boosters to protect the most vulnerable, lessen pressure on health services, and mitigate economic impacts,” said a note on the randomised trial, billed as the first booster study after two doses of the Covid vaccine were given.

The AZ vaccine has been deployed in over 180 countries, and Pfizer in more than 145 countries.

“It’s really encouraging that a wide range of vaccines, using different technologies, show benefits as a third dose to either AstraZeneca or Pfizer-BioNTech. That gives confidence and flexibility in developing booster programmes here in the UK and globally, with other factors like supply chain and logistics also in play,” said Professor Saul Faust, trial lead and Director of the NIHR Clinical Research Facility, University Hospital Southampton NHS Foundation Trust.

This study was funded by the UK Vaccine Taskforce and National Institute for Health Research. The vaccines studied included those from AZ, Pfizer, Novavax, Janssen, Moderna, Valneva and Curevac. The study looked at safety, immune response (immunogenicity) and side-effects (reactogenicity) of seven vaccines when used as a third booster jab, explained a note on the study published in The Lancet .

However, it added: “Little data exist on the comparative safety of Covid vaccines, and the immune responses they stimulate when given as a third dose.” (The reference being to companies using their own vaccines as third doses, or a homologous boost.)

“While 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” said Professor Faust.

India implications

AZ is present in India as Covishield, produced and marketed by Serum Institute, which also has the mandate to make the Novavax vaccine. The J&J and Moderna vaccines have permissions, but are not in the market.

Two other vaccines available in India, including the Covaxin and the Russian vaccine Sputnik V (whose single dose version Sputnik Light is projected as a universal booster) are not part of this study.

“When we set up the trial, we only had access to the vaccines that the UK Vaccine Taskforce had negotiated for the UK – timelines unfortunately did not allow the VTF to consider other vaccines for the trial,” Professor Faust told BusinessLine.

Omicron impact?

Responding to whether the boosters would be effective against Omicron, he added: “The broad T-cell immunity against previous/current variants we report is encouraging that we will be protected against the most severe forms of disease for any variants, but we don’t have specific data on Omicron yet, but have provided samples to the UK HSA labs for testing.”

The study showed both antibody-mediated immunity (the primary outcome) and T-cell response (secondary), known to be important in vaccine effectiveness. The T-cells response 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”, the note said.

Published on December 03, 2021

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