Covid-19 not endemic yet, health expert warns against complacency

Covid-19 has not reached the endemic stage yet, a senior health expert said, despite the situation improving over the past two-three months.

Pointing to the high caseload in the northeast and the south, Dr. Anant Mohan, head of the Pulmonary Medicine department at AIIMS, New Delhi, warned against complacency in following Covid-appropriate behaviour. He added that the pandemic had not ended but efforts were being made to bring it under control.

In a video tweeted by the Union Health Ministry, Dr. Mohan said Covid-19 might reach the endemic stage, but added that it was still uncertain when that would occur.

What is an endemic?
An endemic, like influenza, is something present all the time.

Endemicity occurs when a large section of the population develops antibodies, either by infection or vaccination, causing small, sporadic outbreaks that don’t reach the epidemic or pandemic stage.

Leading virologist Dr. Shaheed Jameel said only those pathogens that didn’t have animals as a reservoir could be eradicated. In case of SARS-CoV-2, it will keep circulating as it is present in animals. This means it will cause the disease in people who have not been vaccinated against or exposed to the virus.

If enough people have been infected or are vaccinated, then the virus could only cause symptomatic infections and not the disease, Dr. Jameel said.

Endemicity of SARS-CoV-2
How fast Covid-19 becomes endemic will depend on how quickly the SARS-CoV-2 virus spreads and mutates.

Dr. Jameel said it was more important to focus on vaccination and limit transmission instead of debating whether the virus had become endemic or not. He added that it was impossible to predict when the virus would become endemic.

The Indian Council of Medical Research’s last serological survey showed that roughly two-thirds of India’s population had developed antibodies. Of those, some would have developed the antibodies after being vaccinated. However, since India’s vaccination rate is still low, the assumption is that most people who have developed antibodies have been infected, but not all have had the disease. Dr. Jameel explained that a majority of this population would be protected from symptomatic disease later; they might get infected but were protected.

However, this theory is based on the assumption that the virus is not going to mutate to transmit easily and evade immunity.

The antibodies
Professor Partha Majumder, the Centre’s National Science Chair, said how long the antibodies would last was an open question.

Almost everybody has now developed antibodies that possibly reduces the likelihood of infection. Even if people are infected, they may not develop severe disease, Professor Majumder said.

He added that Indians might already have developed herd immunity, indicating that most have antibodies, and hence infections might not cause severe disease.

Rising numbers
Professor Gautam Menon, who teaches biology and physics at Ashoka University, said a more or less constant infection level could be expected within the population. The chances of severe illness, hospitalisation, or death will become increasingly smaller as more people are vaccinated, he said.

He added that with viruses mutating constantly, the question is if a new variant with a higher transmission rate than the Delta variant that could evade immunity would come along.

As long as it does not, Professor Menon said, small reinfections and vaccine breakthroughs would help keep the infections low. He said it was more likely that there would be a steady level of cases, with spikes in regions of low prior seroprevalence and vaccination.

Professor Menon added that it was unlikely that the caseload could be comparable to the second wave.