NEW DELHI: The mutations in coronavirus, waning population immunity or unrestricted mixing of people could drive a third nationwide Covid-19 wave in India, but it is unlikely to be as severe as the second wave, a new study by ICMR researchers has said.
The scientific paper, jointly prepared by ICMR and Imperial College, London, study by Indian and UK researchers has indicated that while the timing and pattern of the third wave will depend on such factors, the size of the surge could remain either midway between the first two waves or be smaller than even the first wave.
ICMR's director general Balram Bhargava and chief scientist Samiran Panda are co-authors of the study.
The paper published in the ICMR’s Indian Journal of Medical Research said that immune-mediated mechanisms- waning immunity or viral evolution for immune escape- are unlikely to drive a severe third wave if acting on their own, unless such mechanisms lead to a complete loss of protection among those previously exposed.
Likewise, a new, more transmissible variant would have to exceed a high threshold of reproductive factor—rate at which an infected individual infects other—should need to be higher than 4.5 to cause a third wave on its own.
However, plausible mechanisms for a third wave include a new variant that is more transmissible and at the same time capable of escaping prior immunity and lockdowns that are highly effective in limiting transmission and subsequently released.
In both cases, any third wave seems unlikely to be as severe as the second wave, noted the researchers.
The study titled “Plausibility of a third wave of Covid-19 in India: A mathematical modelling-based analysis” also said that the emergence of a third wave could be substantially mitigated by the expansion of vaccination.
If the rollout of vaccine is in such a way so as to cover 40 per cent of the population with two doses over a period of three months following the end of the second wave, symptomatic cases could be reduced by around 55 %, the scientists said.