The biggest and ongoing Covid-19 wave in China has started speculations about a fourth wave in India. There have been high-level meetings at the national and state levels, mock drills and some advisories based on speculation. Understandably, this has created a bit of panic and apprehension among citizens. Is a fresh national Covid wave in India a real possibility? Let’s examine the issue objectively.
A disease outbreak or an epidemic – in any setting or country – is the outcome of complex interactions between the “epidemiologic triad” of the agent, host and environment factors. In Covid-19, the agent is the Severe Acute Respiratory Syndrome Coronavirus 2, or SARS-CoV-2. The hosts are the people and the factors linked to them such as the susceptibility pool, population-level immunity, age distribution, burden of co-morbidities, etc. The environmental/external factors are the level of social and commercial activities, travel, and any prevalent infection that may interfere with the spread of diseases.
SARS CoV2- in early 2020 had epidemic and pandemic potential. Back then, it was a new pathogen with high transmissibility to which the entire population was susceptible. However, three years later, the virus is not novel anymore, and people are protected from moderate to severe disease due to prior natural infection or vaccination and in most cases, both. More specifically for India, after three Covid-19 waves, an estimated 95 per cent or more of India’s population — across all age groups, including children — have been naturally infected at least once and 97 per cent of adults have received at least one shot of the Covid-19 vaccines. By the end of 2022, an estimated 98 per cent or more of India’s population has developed immunity and thus, have a very low risk of moderate to severe disease.
Yet, a fresh surge or spike in Covid-19 cannot be completely ruled out. However, a fresh national wave in India is possible only if there are major changes in one or more components of the epidemiologic triad. Has the Covid wave in China changed the situation for India? In the agent factor, Omicron (B.1.1.529) and its sub-lineages such as XBB, and BF.7 are spreading in China. The Omicron strain caused the third wave in India and its sub-lineages have been present and circulating in the country for a few months. In the ongoing Covid-19 pandemic, new waves have always been caused by the emergence of new variants of concern (VoC). The same VoC is not known to cause another wave in the same settings. Therefore, considering there is no new VoC reported, the agent factor remains unchanged for India.
Among the host factors, since the third wave in January 2022, additional people have received Covid vaccines and precaution doses. Alongside, Omicron and its sub-lineages have continued to cause asymptomatic infections. Even if we factor in the decline in antibody levels since vaccination or natural infection, regular natural exposure to sub-lineages is likely to have balanced that, as evident from the low rate of moderate to severe Covid cases. Arguably, the susceptible pool of people has been further reduced.
On the environmental or external factors, in comparison to early this year, social activities and interactions have increased and the use of masks and adherence to physical distancing has gone down. However, the usefulness of these tools was greater when people were without immunity and susceptible (not exposed to the virus and not vaccinated). Environmental factors come into play only when there is a change in the agent factor, that is, the emergence of a new VoC. Since currently, Omicron is the only VoC, except for a small fraction of vulnerable and unvaccinated population sub-group, the utility of masks and physical distancing as public health measures is limited.
So, if we interpret the epidemiological, virological and immunological evidence, supplemented by the data from genomic and wastewater surveillance and the trend in reported cases and deaths in India, it is logical to conclude that the ongoing wave in China is extremely unlikely to cause a fresh national wave in India.
Yet, much of the discourse on how to prepare for the “possible” next wave is influenced by opinion and isolated interpretations of past information. The recent argument that “the next 40 days will be crucial” in India is inferred from the patterns of previous Covid waves. For diseases with epidemic potential, the “context” matters a lot. Three years into the pandemic, the context has changed, and past patterns are not a helpful guide for decision making. Another assertion that “let’s be prepared for the worst-case scenario” is the weakest of all. Such an approach was acceptable at the beginning of the pandemic with many unknowns; the response now needs to be guided by science, informed by all possible sources of evidence, and factoring in the learnings. It needs to be nuanced and setting-specific.
Indeed, Covid has not disappeared, but the virus and disease are unlikely to ever completely go away. Even when the pandemic gets over, there would be waves and spikes (localised or at the country-level) at unpredictable intervals in different parts of the world. Countries including India should be prepared for such an eventuality. At present, there doesn’t seem to be any role of mask mandates, universal testing, enforced physical distancing or any other form of restrictions.
Covid-19 has become endemic in India for the last few months, and it is time the government downgrades Covid-19 to the status of other respiratory illnesses. It is also the time that India develops an evidence-informed “Covid-19 endemic stage response plan”.
The writer is a consultant physician and epidemiologist and the lead co-author of Till We Win: India’s fight Against The Covid-19 Pandemic
