By now the delta variant accounts for 50% of all Covid-19 cases in countries around the world. The World Health Organization has declared the Delta variant and its newer mutant as a variant of concern (VOC). In India, the Delta variant, is called the ‘double mutant variant’ as it has two mutations E484Q and L452R. It originated in Maharashtra last year and spread to the rest of the country.
After which, it spread to other countries and is the most prevalent strain worldwide. Epidemiologists in India believe that the Delta variant and its new mutant — Delta Plus have the potential to trigger the third wave. Now, the biggest question people’s mind is, ‘Do current vaccines available in India protect against these mutating viruses? And do Indians need a booster dose to improve immunity against such mutants?’
How does the vaccine work against the virus and its mutants?
Post vaccine breakthrough infections are being reported even in fully vaccinated individuals. While non-adherence to Covid-appropriate behaviour has a role to play in this, there is no denying the fact that emerging variants of concern have also played their part in reinfections.
The major VOCs in India are the B.1 (the first lineage of ancestral Wuhan virus also called G614), alpha variant, and delta variants. Few cases of Beta and Gamma variants have also been reported in the country. In keeping with this knowledge, scientists from across the world say that the Delta variant can escape the defense shield of vaccines. Yet, inoculation provides enough immunity that can help in avoiding hospitalisation.
The 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).
What scientific evidence says?
As per the report, a modest reduction in vaccine effectiveness is witnessed. Nevertheless, a clear effect of both vaccines was noted with high levels of effectiveness after two doses. This study also clearly highlights the need to take both doses of the vaccine. A large study by the Indian Armed Forces (IAF) showed nearly 93% reduction in Covid-19 infections amongst IAFs healthcare and frontline workers who had taken Covishield vaccine. This study took place when the country was struggling with the 2nd wave of Covid-19. The study revealed that fully vaccinated groups were better off with up to 82% of 1.59 million showing seven deaths only.
How will we know when our vaccines are losing their effectiveness?
Scientists are searching for biological markers that could reveal when the protection from a vaccine is no longer enough to hold back the Coronavirus. It is possible that a certain level of antibodies marks a threshold: If your blood measures above that level, you are in good shape; but if you are below it, you are at greater risk of infection.
Can people switch vaccine brands when a booster dose is available?
Yes. Booster doses will take some time to be available in the market. Past experiences and research on other diseases suggests that switching vaccines can strengthen boosters. In the Covid-19 context, the emergence of variants has accelerated research on boosters as well. However, till then building defense through current vaccination programs is a must. If people are waiting for a magical moment to get vaccinated, this is it.
(The author Dr. Rahul Pandit is the Director-Critical Care, Fortis Hospitals Mumbai & Member of Maharashtra’s Covid-19 Taskforce)
