Arushi Bidhuri
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Written By: Arushi Bidhuri | Published : July 20, 2021 2:11 PM IST
As the Delta variant spread rapidly around the world, there are growing concerns that COVID-19 vaccinations will not provide adequate protection against emerging SARS-CoV-2 virus strains. This has led to the discussion of a possible third booster shot. Many scientists and governments began debating about the possibility of a third "booster" shot to pad up on the immunity from the first & second dose. Due to this, many countries like Israel have started offering booster shots of Covid vaccines to at-risk adults and those who are vulnerable. To understand everything about the third covid vaccine, we talked to Dr Sandeep Patil, Chief Intensivist, Fortis Hospital, Kalyan. Read on to know all about the booster shot and if you need it.
A booster shot works as an additional dose that strengthens protection and offers more defensive properties to the immune system to prevent any attacks from the pathogen, or in this case, a virus.
Just as other available vaccines, booster shots also contain inactive/ altered/ weakened/ mRNA fragments which train the immune system. The primary reason why booster shots are being introduced right now is to target the variants of concern (VoC) that have been clinically found to lower the efficacy of the COVID-19 vaccines we have right now. Additionally, booster shots can also be altered or tweaked to suit specific needs or offer preventive protection against variants of interest, or concern.
The reasons for consideration of booster stems from the fact that new variants of concern have been said to spread across the world. In such circumstances, some people with frail immunity, preconditions, or immuno-compromising conditions, may not be full protected by COVID-19 vaccines doses available right now, or may not have lasting antibodies. The availability of booster shots will be particularly helpful for people with such conditions since it would amp up the levels of protection offered. Healthcare workers and frontline staff, who face high exposure rates and dangers from the pandemic may also stand to gain from booster shots.
In India, experts revealed that it's too early to contemplate a third vaccine shot or a booster. In the same light, WHO, the European Medicines Agency, and the European Centre for Disease Control stated that it is still too early to tell if a third dose is needed for people around the world. There is not yet enough data gathered on the same, and there are ongoing studies to understand how long protection can be achieved after vaccination of two doses, also considering the spread of variant.
Additionally, vaccines available in the country, Covishield and Covaxin work against the four VOCs. Covaxin (BBV152) is manufactured using the original ancestral variant G614 (virus strain (NIV-2020-770) containing the Asp614Gly mutation). The virus was captured from a COVID patient to ensure that the pathogenetic virus is used for manufacturing vaccines. It was further grown on Vero cell lines and chemically inactivated. Covishield, the ChAdOx1 nCoV-19 vaccine (AZD1222), was developed at Oxford University and consists of a replication-deficient Chimpanzee adenoviral vector ChAdOx1, containing the gene for (early) spike protein, nCoV-19. Sputnik is an adenoviral-based- a two-part vaccine against the SARS-CoV-2 coronavirus. Initially produced in Russia, Sputnik V uses a weakened virus to deliver small parts of a pathogen and stimulate an immune response. Studies show that this vaccine is also effective against new variants of COVID.
Moreover, the National Institute of Virology (NIV) is examining the efficacy of two doses of BBV152 (Covaxin) against the variants confirmed a reduction in neutralization titers with sera of COVID-19 recovered cases (3.3-fold and 4.6-fold) and BBV152 vaccinees (3. 0 and 2.7-fold) against B.1.351 and B.1.617.2 respectively. The study highlighted that Covaxin demonstrated a protective response against VOC B.1351 and B.1.617.2. The NIH has also acknowledged the efficacy of Covaxin against the delta variant. As per the ICMR, any future waves will be controlled and delayed if more people get vaccinated and follow COVID-appropriate behaviour effectively.
Therefore, in India, we do not see an urgent need for a booster dose. There are still so many people who are not fully vaccinated with two doses, let alone three. Our focus should ideally be on ensuring that maximum people above 18 years get the two doses and following COVID-appropriate behaviour should be our holy grail. Then only, we can bring down the burden of COVID on our nation.
