Endemic: Fourth Covid wave unlikely as immunity levels rise, say experts

After oscillating between surges or ‘waves’ of Covid infections and ‘retreats’, the world seems to be finally getting back on its feet. Experts feel the country is entering the endemic phase of infection. The chances of a debilitating fourth wave in India are low unless a major mutation happens.

T Jacob John, senior virologist and former head of the departments of clinical virology and microbiology at Christian Medical College, Vellore, feels a fourth wave is unlikely in India because of epidemiological reasons and substantial immunity in the population.

Steady and stable infection rate with minor fluctuations for four weeks or more is when the disease is in endemic stage. “The third wave is just over in India, and it has reached the 10,000 daily cases-mark. We have reached a bottom or valley, and if this stays like this for four weeks, the infection is entering endemic phase,” he adds.

“With the available knowledge of the epidemiology of the virus, there will be no fourth wave in India, in my opinion. I think the pandemic is going to disappear soon,” the virologist adds.

Industry veteran and chairperson of Biocon Group, which has launched biologic drugs used to treat Covid, Kiran Mazumdar-Shaw told Business Standard, “We entering endemic phase. The pandemic is waning.” She adds that the vaccines have worked.

“We were anticipating a very severe third wave, and we have not seen anything like that. This clearly shows that viral vector-based vaccines and others work because in India, the bulk of the vaccination has been through Covishield and Covaxin. Therefore, it is not accurate to say that messenger ribonucleic acid vaccines are better than others,” says Shaw.

After the Delta variant-led wave, India was the first country to reach endemic stage. Taiwan, Israel, and Japan, too, reached endemic prevalence when the infection rate was stable. India had five to six months of endemic prevalence after which Omicron hit.

Vaccines will continue to play a critical role in the future. John says that booster dose immunity does not diminish easily. He explains that any vaccine dose given within a gap of less than four months of the first dose is part of primary dosing.

“After a gap of six months, if we give a shot, it’s a booster shot. The gap can be longer. But after someone has been ‘boosted’, we do not expect immunity to decline for at least a year,” he says.

Mazumdar-Shaw, too, feels that annual vaccinations should become the norm.

“We need to get into annual vaccinations from a protection point of view. The whole world needs to get vaccinated, and we need to continue to wear masks,” she says, adding, “We have developed natural immunity.”

“We have gone through a major third wave which was not devastating. The chances of getting a lethal variant are low,” says Mazumdar-Shaw. 

Pankaj Patel, chairman of Zydus Lifesciences said at a recent event that the pandemic was waning and from his experience he did not expect any more lethal variants coming up soon. 

Why are experts optimistic about not being hit by a massive wave?

“The speed of the virus mutation depends upon how fast it is multiplying in people. In epidemics, mutations are more likely, but in the endemic phase, mutations are less likely. Therefore, in the endemic phase, with high levels of immunity, the chances of several mutations are lower,” says John.

Speaking of mutations, P S Narang, director-paediatric, Max Super Speciality Hospital, Shalimar Bagh, Delhi, says there are two types of mutations —  major mutation (which we call shift) or a minor mutation (drift). The virus is continuously mutating. In case of minor mutations, we don’t face issues with immunity. When there is a major shift, it becomes difficult for the immune system to fight the virus.

“Mutations occur in live hosts, and as cases go down, the chances of mutation go down as well. If the virus does not mutate much, this Covid-19 wave will die. After the third wave, we are hoping this infection will become endemic,” adds Narang.

A second reason behind this optimism is that the cases in India are going down despite the lifting of Covid restrictions. 

Dileep Mavlankar, director, Indian Institute of Public Health and former professor of IIM Ahmedabad, says, “This is a sign that the infection is entering endemic phase. I do not expect a fourth wave with a huge surge in cases anytime soon unless there is significant mutation in the virus, or we import a completely different strain of the virus.”

A recent IIT Kanpur study has claimed that a fourth wave may hit India around June 22. The study led by IIT Kanpur’s Department of Mathematics and Statistics shows that the severity of the fourth wave will depend upon the emergence of a possible new coronavirus strain and vaccination status across the country.

Virologists do not agree with such mathematical models or projections.

“If I am a mathematician and know little about virus behaviour, I will spot a pattern in the three waves, and would say that there will be another wave. But every pandemic goes through this pattern and dies out. This pandemic is dying out. Mathematical pattern spotting does not work with viruses; it works with weather patterns, flooding, etc,” says John.

Experts, however, speak about not lowering vigil and recommend institutionalising grass-root level screening.

Suman Chakraborty, professor and dean of IIT Kharagpur and inventor of COVIRAP technology for rapid nucleic acid testing, feels that grass-root level testing has to be institutionalised to detect and isolate cases faster.

“Let’s say in schools, offices, we need to test anyone with influenza-like symptoms or even asymptomatic symptoms at regular intervals. It’s important to detect and isolate the infected individuals early,” adds Chakraborty.