India better prepared than China for new Covid wave

After China suddenly opened its doors widely to the SARS-CoV-2 virus, a flood of Covid cases and deaths are being reported by global media, even though official counts from that country are low. While all reports need verification, there is little doubt that China has many vulnerable people who were unexposed to the virus earlier or had not been fully vaccinated. Low vaccination rates among the elderly in China are of particular concern. Taking cognisance of rising case counts in China, Japan, South Korea and the US, GoI has issued new advisories. What are the pathways that this fresh spurt of Covid cases can take to endanger the world? How will India be affected? Within Covid’s cauldron of complexity, there is a churning variability in virus evolution, policy response, public behaviour, evolving science and emerging technologies. As that mix changes, answers to our questions too will change over time. For the present, we need clarity on the following questions.Is the surge in China due to the ancestral virus or a Delta variant, either or both of which were locked within a closed society and now find sudden release into a highly susceptible population?Or is it due to members of the Omicron family, which are currently dominant globally?Countries other than China are witnessing a rise in cases due to new Omicron sub-lineages, which are emerging with surprising speed of evolution.The dangers that China faces, and therefore the rest of the world might too, will be partly determined by whether China is now being haunted by past zombies let loose or is witnessing the air race of young Omicron variants flying fast.Or will a totally new variant emerge from China that may find the whole world vulnerable? We await that information from China, based on genomic analysis of new cases and their clinical outcomes. While current versions of Omicron have acquired superpowers of high transmissibility and immune evasion, they have exhibited lower virulence than the ancestral virus or the Delta variant. This is possibly due to a trade-off guided by evolutionary biology which requires that the virus should not decimate its host when the number of susceptible individuals is diminishing due to acquired immunity. medium96403997However, when the virus finds a population where the levels of such immunity are low, the virus may have no such restraint. If it stays long in the body of an immunocompromised person or an elderly person with weak immune defences, the virus has time to mutate several times. Some of them can spread as dangerously virulent variants. That is China’s problem and the world’s worry. In the current scenario, genomic surveillance becomes vital.Are new variants landing?Based on their structure, do they have the potential for rapid spread?Will they evade previously acquired immunity?Does the new variant have structural features which have been associated with high virulence in previous versions? But even in high virulence, our bodily defences are probably better prepared now to counter those weapons than when it hit immunologically naive populations. Recent scientific reports caution that new Omicron variants are increasingly capable of evading the neutralising effect of a variety of monoclonal antibodies prepared against earlier variants. However, we also know that there is a strong backup defence from T-cells, which have long memories and a strong capacity to capture the virus and eliminate the danger. So, even when the antibody defenders are incapacitated, trust the T-cell goalkeeper to save the penalties. India may still be in a relatively safe zone with its hybrid immunity. People may get infected but experience only mild illness. Persons who have weak immune defences due to serious pre-existing health conditions or advanced age will be vulnerable and must be protected. Since all penalties cannot be saved all the time even by capable T-cells, we must depend on strong defences not to open the field for the virus to enter the guarded box of our airways.We need to ensure that masks are worn in indoor locations and closed public transport if case counts rise rapidly.We should use the protective power of ventilation which will prevent high viral loads from massing troops for bodily invasion, as air currents dispel viral clouds.The need for boosters is unproven, as new bivalent vaccines too have not convincingly demonstrated protective effects against infection by new Omicron variants.However, elderly persons and immunocompromised individuals may be given a heterologous booster for possible protection.If information from China and other countries indicates that there are no dangerous new variants, a general population advisory for fresh vaccination is avoidable. India’s strategy should be a combination of vigilance through clinical and genomic surveillance, scenario-based planning, keeping all systems on alert for a rapid, scaled up public health response when needed, getting people to follow sensible Covid-appropriate behaviours attuned to changing levels of threat and constantly gathering global intelligence on the patterns of infectivity, immune evasion and virulence of currently circulating variants. This requires solidarity and team play at both national and global levels. If we play to that game plan, all countries can win the World Cup against Covid, despite a poor start. The writer is a cardiologist, epidemiologist and Distinguished Professor of Public Health, PHFI