With falling rates of Covid-19 infection in India and surveys suggesting nearly 300 million people may already have antibodies, some experts believe the worst of the disease has passed, despite a recent uptick in two hard-hit states.
"There is a human barricade for the virus," said Bhramar Mukherjee, an epidemiologist at the University of Michigan, who with a team of researchers, has been modelling the trajectory of the outbreak in India.
"By the end of March, we should see a very slow, steady decline (in cases)," she added.
Cases that were rising by nearly 100,000 a day in September are now growing at just 10,000 a day. And India's official number of total infections, which was projected to surpass that of the United States in late 2020, now stands at 11 million, well behind the US tally of about 28 million.
Total deaths so far in India are just under 156,000, the world's fourth-highest number of fatalities.
"India suffered through a lot and because it suffered through a lot, it's reached the other shore now," said Ramanan Laxminarayan, an epidemiologist at the Center for Disease Dynamics, Economics & Policy, a research firm based in Washington, DC and New Delhi. "I don't see the prospect of a second wave in India. If it does happen, it will likely be a modest one."
A recent government serological survey indicated 21.5% of Indians were likely infected by Covid-19, giving them a degree of immunity, while antibody tests on more than 700,000 people by a diagnostic company showed that 55% of Indians may have already been infected.
To be sure, not all epidemiologists agree India is out of the woods. The country is currently battling a surge in cases in two states - Maharashtra and Kerala, which account for a combined 70% of nationwide active cases.
Even those predicting further declines in cases, like Mukherjee, warn that India will need to continue Covid-19 containment measures and surveillance of new variants, besides aggressively vaccinating its people.
More socializing, coupled with a recent restart of local trains in the financial hub of Mumbai, could be causing the spike in Maharashtra, say experts, while a restart of schools in Kerala is being blamed for the surge there. New clusters have also been identified in the tech hub of Bengaluru.
"Even though there are advisories against large gatherings, people have started to take it easy," said Pradeep Awate, a senior health official in Maharashtra.
Still, Mukherjee notes the "percentage of cases that require hospitalizations in Kerala and Maharashtra has gone down."
Vaccination
The reason why millions of Indians are asymptomatic — as survey numbers suggest — has flummoxed experts.
Theories range from India's early lockdown implementation to its youthful population and an intrinsic immunity among Indians. Some say an open-air lifestyle in villages could have prevented a surge in rural India, where two-thirds of India's 1.3 billion people live.
But epidemiologists say finding the true reason will require research that could take years.
While experts agree many Covid-19 cases and deaths may be under-reported in India, available indicators like hospital-bed utilization rates point to a falling curve.
Epidemiologists say a key factor would be how aggressively India moves on its vaccination drive.
"If vaccines are given in large numbers right away, we're going to be in a very good position," said Mukherjee. "By the time infection-induced immunity wanes, people will get vaccine-induced immunity."