Do we need COVID-19 vaccine booster shot?

Amid supply delays, safety concerns that have slowed vaccination campaigns and deadly variants, many countries are exploring the option to switch to separate Covid-19 vaccines for second doses or booster shots.

Health experts, however, say it is too early to say these booster shots will be required.

World Health Organisation’s chief scientist Soumya Swaminathan has said there is not enough information to either confirm or dismiss the requirement for a booster shot after vaccination against Covid-19.

“We do not have the information that’s necessary to make the recommendation on whether or not a booster will be needed,” Soumya Swaminathan told Bloomberg. “The science is still evolving,” the WHO chief scientist was quoted as saying.

Such a call is also “premature” since high-risk individuals in most of the world haven’t yet completed a first course of vaccination, Swaminathan added.

What are booster shots?
The present vaccines against Covid-19 comprise two doses. Since it is not clearly known how long the effect of vaccination stays, many countries are thinking of an annual or booster shot.

The United Kingdom is likely to roll out Covid booster shots to avoid another surge. Seven different vaccines are being tested in volunteers in England in the world’s first booster study, Health Secretary Matt Hancock said last month.

The United Arab Emirates have made the Pfizer/BioNTech coronavirus vaccine available as a booster shot to those initially immunised with a vaccine developed by the China National Pharmaceutical Group (Sinopharm).

Bahrain said on June 4 that eligible candidates could receive a booster shot of the Pfizer/BioNTech or the Sinopharm vaccine, regardless of which shot they had initially taken.

The U.S. National Institutes of Health (NIH) said on June 1 it had started a clinical trial on fully vaccinated adults to evaluate the safety and immunogenicity of a booster shot of a different vaccine.

Mixing of vaccines a viable option?
On her take on combination of vaccines amid supply shortage, Soumya Swaminathan said, “It seems to be working well, this concept of heterologous prime-boostThis opens up the opportunity for countries that have vaccinated people with one vaccine and now are waiting for the second dose they have run out of, to potentially be able to use a different platform vaccine.”

The health expert, however, added that early data from the UK, Spain and Germany suggested a “mix-and-match” regimen using two different types of vaccines generated more pain, fever and other minor side effects compared with two doses of the same inoculation.

“Still, the so-called heterologous prime-boost combinations appear to spur a more robust immune response, leading to both higher levels of virus-blocking antibodies and the white blood cells that kill virus-infected cells,” Soumya Swaminathan said. India Today