It is viewed that two of the widely available vaccines — Covaxin and Covishield — in India prevent disease severity. However, the scientific community believes two vaccine doses may not be enough, as the raging delta plus variant has an additional mutation (K417N) and two lineages (AY.1 and AY.2), with immune evasion properties.
“How long would the vaccine protection last? Claims vary. But, reasonable predictions indicate that protective antibodies may last for six months after the vaccination schedule is complete,” professor G Padmanaban, senior science innovation adviser (BIRAC), department of biotechnology told TOI. “There could be longer lasting protective ‘memory’ cells as well. All these can vary between individuals. This is where it is worth planning for a third dose vaccination in the middle of 2022.”
Padmanaban, the former director of Indian Institute of Science, Bengaluru, said that while most mutations tend to inactivate the virus, one cannot rule out a more infectious new mutation.
“So, one hopes that a third dose offers adequate protection till the virus loses its infectivity — and is tamed to become more of an annual flu visitor — if not give us complete respite,” he said.
While India contained the first wave, the second, which began around March 2021 hit the country hard. After showing some signs of decline, the number of positive cases is again heading north, raising fears of a third wave.
A senior health expert with the epidemiology and communicable diseases division of ICMR said it is important to discuss new strategies to contain the virus, bolster health infrastructure and prevent more deaths.
Former Centre for Cellular and Molecular Biology director and advisor Dr Rakesh Mishra said the country is at a crucial stage, and in the next five-six months, the two-dose initial vaccination must be completed. “Once its done, third dose is fine. We plan a third dose for the population as one of those strategies to be discussed,” Mishra said.
Padmanaban said one strategy to protect against new variants could be to make new vaccines against the delta/delta plus variants, employing the inactivated virus (similar to Covaxin) or a sub-unit vaccine (similar to Covishield). “Trials would be needed to establish whether such ‘mutant’ vaccines are as effective,” he said. “For now, Covid-19 appropriate behaviour, wearing face masks in particular, and vaccination are the only proven strategies to curb the pandemic,” he said.