ICMR study says third-wave of Covid-19 unlikely to be as severe as second

New Delhi: In a study conducted by the Indian Council of Medical Research (ICMR), it was found that a substantial third wave could occur, though it may not be as severe as the second wave. The study was published in Friday’s issue of the peer-reviewed Indian Journal of Medical Research, titled ‘Plausibility of the third wave of COVID-19 in India: A mathematical modeling based analysis’.

‘This study demonstrates plausible mechanisms by which a substantial third wave could occur, while also illustrating that it is unlikely for any such resurgence to be as large as the second wave,’ the study said. Researchers noted that projections are subject to uncertainty, adding that vaccinations must be scaled up to ‘mitigate against any eventuality. ‘Preparedness planning for any potential future wave will benefit by drawing upon the projected numbers based on the present modeling exercise,’ it added. In the study, researchers examined four potential mechanisms of Covid-19 transmission using a compartmental model of SARS-CoV-2 transmission.

‘In the first mechanism, the possibility of waning immunity was considered that would put previously exposed individuals at risk. Second, the emergence of a new viral variant that is capable of escaping immunity to previously circulating strains. Third, the emergence of a new viral variant that is more transmissible than the previously circulating strains. Fourth, of current lockdowns affording fresh opportunities for transmission,’ the study read.

The study found that immune-mediated mechanisms (waning immunity or viral evolution for immune escape) are unlikely to lead to a severe third wave if acting on their own unless such mechanisms lead to a complete loss of protection in previously exposed individuals. They noted that a new, more transmissible strain also needs a very high infection rate (R 0 > 4.5) to cause the third wave on its own. The R-value indicates how quickly a disease spreads within the population.

The ICMR study mentioned two mechanisms through which a severe third wave could occur. In the first case, a new variant becomes transmissible and subsequently escapes immunity, and second, when lockdowns are highly effective in limiting transmission and subsequently relaxed. Researchers suggested that rapid scale-up of vaccination efforts could be an important component in mitigating these and future waves of the disease.