Do We Need A Third, Booster Shot Of COVID Vaccine As The Virus Mutates? What Studies Say So Far

While India is trying to 'adjust' with one dose, increasing the gap between doses or no vaccination at all for COVID-19 recovered, many countries around the world where a significant portion of the population have been vaccinated are taking a different approach.

Amid fears that the delta variant of COVID-19 which was first identified in India will soon become the dominant strain globally, many countries are considering giving a third, booster dose to their citizens to improve their immunity.

That is because studies so far suggest that the existing vaccines only offer limited protection against the delta strain as compared to the nearly 90 per cent efficacy most of them had shown against the alpha and beta strains.

AP

Clinical trial in UK

In the UK, a clinical trial is already underway to determine if a third dose of COVID-19 is needed to improve immunity.

NEWS: @BTHFT & the @UniofBradford today launched a world-first clinical trial to give scientists around the globe a better idea of the part booster doses of the #CovidVaccine could play in protecting individuals from the virus. #WeAreBradford

FULL STORY: https://t.co/MSicKsIBJb pic.twitter.com/xDngfVFqzX

¡ª Bradford Teaching Hospitals NHS FT #HandsFaceSpace (@BTHFT) June 1, 2021

What Pfizer and Moderna say

Pfizer and Moderna had recently announced that people who have received both doses of the Pfizer-BioNTech or Moderna coronavirus vaccines will probably need a booster shot this year and might need an annual shot thereafter.

¡°A likely scenario is that there will be likely a need for a third dose, somewhere between six and 12 months and then from there, there will be an annual revaccination, but all of that needs to be confirmed. And again, the variants will play a key role,¡± Pfizer CEO Albert Bourla recently told CNBC.

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In India, earlier this month, an expert panel of the Drugs Controller General of India (DCGI) had permitted Bharat Biotech to give a third dose of its COVID-19 vaccine Covaxin to a few volunteers in its clinical trials.

Bharat Biotech has proposed a booster dose after six months of the second dose.

What experts say

Samiran Panda, director of the ICMR National AIDS Research Institute, said if the companies are deciding on giving a third booster dose after two doses then it should be based upon data on immunological memory.

This means that after two doses what is the status of antibody concentration and after how long it comes below a level after which one needs the third booster dose, he said.

I wonder why the companies are suggesting this and what is the data because COVID-19 we came to know in December 2019 and the vaccines were made in April and August. So we don¡¯t have enough data and I think the proposal for third dose is based on a conjecture rather than the time that needs to lapse after which we will have data on how many shots are needed. So time has not come as yet, Panda told PTI.

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He said now when these companies are talking about boosters there comes the question what would these boosters do.

¡°These boosters are supposed to boost up the immunity to tackle the dwindling concentration of antibodies. It has been found that after six to nine months the concentration of the antibody comes down but that was mostly in natural infections,¡± Panda said.

For organ transplant recipients

Earlier this week, a study published in Annals of Internal Medicine said that a third dose of a COVID-19 vaccine can boost antibody levels in people who previously received an organ transplant.

AFP

¡°To think that a third dose could confer protection for a significant number of people is of course extremely welcome news,¡± said Christian Larsen, MD, professor of surgery in the transplantation division at Emory University in Atlanta, who was not involved in the study. ¡°It¡¯s the easiest conceivable next intervention.¡±

He added, ¡°We just want studies to confirm that ¨C larger studies.¡±