Only way to reduce risk is permanent change in people’s behaviour and adequate vaccination

COVID-19 infections will arise and abate at periodic intervals due to ‘transient herd immunity’ (pool of protected individuals in the population) that each wave of the infection brings, in the absence of an effective vaccine covering a significant proportion of the population. The only way to reduce the risk is adherence to strong governmental monitoring, surveillance and a permanent change in people’s risk behaviour, explain public health experts.

The infection was previously high in August-September 2020 and October-November 2020, when a significant proportion of the population was infected. While some studies had reported about more than a third of the population having antibodies, the actual number of infected may have been much higher taking into consideration the asymptomatic and mild cases, explains Public Health Foundation of India (PHFI)-Indian Institute of Public Health (IIPH), Hyderabad, Director Dr. G.V.S. Murthy

This may have led to the tipping point or ‘transient herd immunity’ with the virus not finding enough susceptible people to infect. As viruses search for hosts to infect for their survival, they mutate to adapt to the environment. Studies have also shown that the infection induced immunity may not last more than 6-9 months. In fact, a study in Denmark showed that the drop-off of antibodies in the older population is up to 60% in six months. It means more of the population becomes susceptible due to reduced antibodies leading to a surge, in the absence of vaccination, he says.

“This trend will become persistent with surges every 5-6 months as the pool of people susceptible to be infected increases. This could also be a reason why there is a surge in cases in March-April 2021, coupled with other reasons. Worry is COVID-19 is likely to have two seasons – spring (March-April) and autumn (Oct-Dec) annually, then there will be heavy price to pay in the future in the absence of high vaccine coverage,” warns Dr. Murthy.

Elections, festivals with internal migrations of even migrant workers, lowered vigilance and surveillance, non-existent contact tracing, opening up of cinemas with full capacity, gatherings for social events — all contributed to the current surge. “As we speak, millions are attending the ‘Kumbh Mela’, once infected at such events, the infected persons are carrying the virus back home and infecting other family members. Clusters of whole families being infected has been observed very commonly in recent months,” points out the director.

The onus is on political leadership. “Though people were disregarding physical distancing, masks and washing hands, they alone cannot be blamed for dropping their guard as they learn from the practices of the political and social leadership. Leaders have to become role-models for others to follow suit. Similarly, punitive measures like fines, if protocols like masks are not adhered to, also goad people to act positively,” he affirms.

Part of the surge could also be attributed to mutations making the virus more infectious, but “mutation monitoring systems are weak and inadequate sampling and lack of adequate genetic laboratories only compounds the problem,” laments Dr. Murthy.



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