Different models have predicted varied peaks for the potential third wave.

COVID-19 third wave predictionsImage for representation/PTI
news COVID-19 Friday, August 20, 2021 - 10:49

It has been nearly two months since the deadly second wave of COVID-19 started subsiding in most parts of India. However, even as lockdowns were lifted, curfews relaxed, and non-essential establishments opened, there were talks of a third wave – When would it happen? Would it be as devastating as the second wave?

Two experts, whom TNM spoke to, said the third wave is unlikely to be as massive as the second one – simply because there aren’t as many people left to be infected in India. “Roughly around 30% of India was infected in the first wave, which took a long time – starting January of last year to about February of this year. And then, a very fast second wave infected a further 30%. So, around a good number of people in India now have had some prior infection. Now, we have vaccinations, too, happening,” said Gautam Menon, a professor of physics and biology at Ashoka University, Sonepat.

“Because of this, I suspect there are many people with some level of immunity already and they will be protected against severe consequences of the disease. They are a little less likely to transmit the disease to other people. Therefore, you may potentially see an increase in cases but it will come from people who have not been vaccinated yet. It is critical to keep that number small by vaccinating faster and at a larger scale,” Menon added.

If there is a new mutant [of the coronavirus], it may be able to produce a wave, said epidemiologist Dr Jayaprakash Muliyil. However, in places like Chennai, for example, where nearly 80% of the population have immunity, how can there be a big wave? “As the virus replicates, it would not be able to jump further from an immune person. To create an exponential rise, there should be susceptible [people]. That’s why Kerala is still having a problem because the [number of] susceptible [people] is very high,” he said.

A threshold immunity

While a majority of states in India are not reporting a very high number of daily COVID-19 cases, states like Kerala and Manipur are exceptions. However, in the case of Kerala, this may not necessarily point to mismanagement of the pandemic. Several factors could be resulting in high numbers – more testing and more reporting, for example.

Moreover, the seroprevalence in Kerala was found to be 44%, which is much lower than places like Karnataka, where the seroprevalence was found to be 69.8% by July this year. This means that a higher number of people in Kerala are susceptible to infection, where the curve of the pandemic has also been steadier than the steep rise and fall in cases as seen in other places. This could arguably point to sustainable management in Kerala, which doesn’t overwhelm the healthcare system.

Read: The paradox of Kerala’s high COVID-19 numbers

So, while some states may be nearing a threshold immunity now, experts have pointed out that more people getting severe infections and higher mortality is not a safe or sustainable way to achieve that immunity. “This virus is more infectious than chickenpox,” Dr Muliyil pointed out. “So, trying to stop it will be very difficult. Most countries have failed. So, you don’t have to feel bad about it. What you should feel bad about is that you have not protected your elderly and the vulnerable with vaccines.”

Further, Gautam Menon said that we must remember that around 30% of people in the country are still susceptible to the virus. “As we vaccinate more and more people, we will see more and more breakthrough infections,” he said.

A breakthrough infection is when a person tests positive for the novel coronavirus two weeks after getting their second dose of the COVID-19 vaccine. The US Centres for Disease Control (CDC) defines such infections that happen at least 14 days after the second shot, the Indian Council of Medical Research (ICMR) does not seem to have the fortnight criterion. Breakthrough infections are likely to be mild and moderate, and rarely, severe.

According to Dr Muliyil, contracting the infection after vaccination could actually provide an unexpected advantage by giving the person additional immunity that lasts longer, especially if the disease has been mild.

So far, according to the Union Health Ministry, less than 1% of people vaccinated with Covaxin and Covishield in April have reported breakthrough infections. While breakthrough infections are unlikely to drive another wave, a vaccinated person could still get infected, putting vulnerable and unvaccinated people at risk.

Experts are advising that people continue to be cautious – such as using the mask judiciously in closed, poorly ventilated spaces and crowds – and especially if they have comorbidities or underlying health conditions that make them more vulnerable to COVID-19 or severe disease. Vaccination does not prevent COVID-19 at all but reduces the severity of the infection.

Will a new variant drive a third wave

The second wave of COVID-19 was, reportedly, significantly driven by the Delta variant of the coronavirus, which is more infectious and has immune escape properties (this is still being studied). However, the Indian health ministry and experts have emphasised that even one dose of vaccine provides significant protection against SARS-CoV-2 variants, including Delta, instead of no vaccine. However, can there be a new variant that evades the immunity provided by a prior infection as well as current vaccines? It’s not very likely, experts say.

Dr Muliyil explained that all viruses have certain aspects that are characteristic to them. So far, all variants of SARS-CoV-2 have ‘respected’ the immunity granted by previous infections as well as vaccination to varying degrees. “If you want to frighten people, you can say that there will be a new ‘ninja’ mutant that will ignore all immunity. If that happens, we will go through [the pandemic] all over again, as it started in 2020. Not just us, the whole world will. But this happens very rarely.”

Gautam Menon said that instead of the steep peak and decline, we are likely to see a steadier “hill” in the third wave. “Most models predict a gentle increase and then a decline [of the third wave]. It could likely be in September or October. We are already seeing a hint of that in Kerala where cases are more or less flat. It is likely that we will have some steady background of cases between about 30,000 to 40,000 for several weeks to come. Whether it builds up into a pronounced third wave is something we still have to see. I am positive that it need not happen. But this depends on what we understand to be the protection that comes from previous infections, the extent to which our current vaccines are working, and social behaviour – to what extent we can maintain [physical] distancing and the care we took earlier in the weeks going forward,” he added.

What other models predicted

Bloomberg reported that as per estimates by researchers led by Mathukumalli Vidyasagar and Manindra Agrawal at IIT Hyderabad and Kanpur respectively, a third wave would peak in October 2021. They said the upward curve could be seen in August. The best-case scenario would consist of India seeing one lakh infections per day, and the worst scenario, 1.5 lakh per day. This wave would be comparatively smaller than the second wave, which saw a record of over four lakh cases in a day on May 7.

An early model by IIT Kanpur’s Professor Rajesh Ranjan and Mahendra Verma and their team predicted that if life went back to normal, India would see a third wave peak by October, but a lower peak compared to the second wave. A second scenario based on life going back to normal and a mutation in the virus predicted a peak by mid-September, which could be severer than the second wave. The third scenario, predicted in the case that stricter restrictions continue in the country, showed the third wave’s peak in late October, and a lower peak than the second wave. These were based on the assumptions that India would be fully unlocked by July 15.

More recently, Anurag Aggarwal, Director of CSIR-Institute of Genomics and Integrative Biology, told Economic Times that we are still witnessing the late phase of the second wave spurred by the Delta variant and the third wave hasn’t begun yet. Epidemiologist Giridhar Babu also told the newspaper that calling it “second” or “third” wave is semantic and that only an “intermittent period of lower levels of transmission” for 1-2 incubation periods of the virus, i.e., 14-28 days, would signify the break between the waves.

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