All seems calm at the moment on the Covid-19 front. Cases are down, hospitals no longer have Covid-19 wards, schools and colleges are finally open, and we are back to worrying about inflation and the price of petrol. Given the experience of the past 25 months, concerns lurk in the background as we go about our daily lives. Will there be a fourth wave? Do we need boosters? At what interval? Is it okay to send young children to school without vaccines? Can the elderly travel? Do we need masks?
Earlier in the year, we had confident predictions of a fourth wave to arrive by the middle of the year. This week we have news of variants XE, BA.4 and BA.5, which have followed the global spread of BA.2, which transmitted at rates faster than the original Omicron. If we have learnt anything, it is that we’re living in an evolving situation. We need to learn and adapt quickly, because preparedness to detect and measure, and speed are essential components of an effective response with a rapidly spreading infection. What, then, is the way forward?
Today, we are not where we were a year ago. The adult population of India has been vaccinated with two doses. It is clear that following the Delta and Omicron waves, that vaccines protect well against severe disease, hospitalisations and deaths, but not against infection. In other parts of the world with other vaccines, it has been shown that, particularly in the elderly population, protection against severe disease declines with time, but these data have come from countries with a much larger older, at-risk population and a different infection history from India, having seen the Delta wave after their populations were vaccinated, unlike India where vaccination covered a small proportion of the population in the first quarter of 2021, when the Delta wave hit.
The national serosurvey in June 2021 showed that about 60% of the population had been infected and 2022 post-Omicron serosurveys from states show up to 80% seropositivity in children who had not received vaccination, indicating the high level of infection in India. Nonetheless, the decision to introduce precautionary doses has been taken, despite the lack of evidence of the need for boosters in the Indian population. Does this mean boosters are not needed or will never be needed?
Since boosters are usually given when vaccines are demonstrated to be no longer protective, we need to be able to measure protection in order to show that protection has declined to a level that needs boosting. The United States Food and Drug Administration has proposed a decline to less than 80% protection against the disease as a trigger for boosting. We should consider whether such a strategy would be appropriate for India, and if yes, there need to be mechanisms to assess vaccine effectiveness. With the integration of CoWin and the testing databases, this is feasible, but needs to be a real-time ongoing exercise measuring vaccination status and timing of all Covid-19 patients admitted to hospitals.
Second, we need to implement in full measure the testing strategy proposed by the government which covers testing of all cases of serious respiratory infections, a proportion of milder infections, outbreaks of respiratory illnesses and risk groups such as travellers. This testing requires clinical and vaccination data to be collected so that the consequences of new variant infections can be picked up early. The separation of sequencing from clinical data must be narrowed so that treating teams on the frontlines and public health professionals are empowered to act. In all testing, the data must be rapidly available to those nearest to the infections, unlike the delayed and centrally controlled practice that hampered local response in the first two years. New variants are a certainty, and if a variant that breaks through vaccine-induced immunity and causes more severe disease does emerge, a rapid response could help contain or slow the spread.
Third, we need research. Diagnostics have been a success story, but we will need to keep up with variants. Research is needed for existing vaccines to understand when to boost and with which combinations, and in what age- and risk-groups. Research is needed for new vaccines that induce longer lasting and broader protection. Antiviral drugs are now available but with a rapidly mutating virus, chances of resistance are high, so we need to understand what is the best way to use anti-viral drugs and monoclonal antibodies to preserve their utility as well as develop new drugs. We need clinical research to identify the best strategies to manage long Covid-19 in adults and children. The list of unknowns is long and addressing the key issues is urgent. Finally, in all of this, we must remember that Covid-19 is not going to go away and we cannot manage it as a special silo forever. In many ways, we have been lucky that this very transmissible virus had a low level of severity and we were able to make good vaccines quickly. We now need to integrate care for Covid-19 into routine health care, and not ignore other infectious and chronic diseases, and build preparedness — not just for the future of Sars-CoV2 and its variant, but for the next outbreak. We have a long way to go.
Gagandeep Kang is professor, Christian Medical College, Vellore The views expressed are personal