NEW DELHI – When the coronavirus pandemic consolidated in India, there were fears that it would collapse the fragile health system of the world’s second most populous country. Infections increased dramatically for months, and at one point India looked like it could outperform the United States as the country with the highest number of cases.
But infections began to plummet in September and now the country reports about 11,000 new cases a day, compared to a maximum of about 100,000, leaving experts perplexed.
They have suggested many possible explanations for the sudden drop, observed in almost every region, including that some areas of the country may have achieved herd immunity or that Indians may have some pre-existing protection against the virus.
The Indian government has also attributed in part the decline in cases to masked clothing, which is mandatory in public in India and the offenses generate heavy fines in some cities. But experts have noted that the situation is more complicated, as the descent is uniform although compliance with the mask is marked in some areas.
It’s more than an intriguing puzzle; determining what lies behind the fall in infections could help authorities control the virus in the country, which has reported nearly 11 million cases and more than 155,000 deaths. About 2.4 million people have died worldwide.
“If we don’t know the reason, without knowing it, you could do things that could cause an outbreak,” said Dr. Shahid Jameel, who studies viruses at Ashoka University in India.
India, like other countries, is missing many infections and there are questions about how it counts virus deaths. But pressure on the country’s hospitals has also waned in recent weeks, another indication that the spread of the virus is waning. When recorded cases crossed 9 million in November, official figures showed that almost 90 per cent of all critical care beds with fans in New Delhi were full. Thursday occupied 16% of those beds.
This success cannot be attributed to vaccinations, as India only started administering shots in January, but as more people are vaccinated, the outlook should be even better, although experts are also concerned about variants identified in many countries that appear to be more contagious. and make some treatments and vaccines less effective.
Possible explanations for the fall in cases include that some large areas have achieved immunity from the herd: the threshold at which there are enough people who have developed immunity to the virus, when they fall ill or vaccinated, for the spread to begin. loosen up, said Vineeta Bal, who studies immune systems at the National Institute of Immunology of India.
But experts have warned that even if herd immunity in some places is partially responsible for the decline, the general population remains vulnerable and must continue to take precautions.
This is especially true because new research suggests that people who became ill with a form of the virus may become infected again with a new version. Bal, for example, noted a recent survey in Manaus, Brazil, which estimated that more than 75% of people had antibodies to the virus in October, before cases increased again in January.
“I don’t think anyone has the final answer,” he said.
And, in India, the data is not so dramatic. A national screening for antibodies by Indian health agencies estimated that about 270 million, or one in five Indians, had been infected with the virus before vaccinations began, that is, well below 70% or higher coronavirus rate, although even this is not safe.
“The message is that a large proportion of the population remains vulnerable,” Dr. Balram Bhargava, who heads India’s leading medical research body, the Indian Council of Medical Research.
But the survey offered other ideas on why infections in India could fall. It showed that more people had been infected in Indian cities than in their villages and that the virus was moving more slowly through the rural interior.
“Rural areas have less density of people, people work more in open spaces and homes are much more ventilated,” Drs. K. Srinath Reddy, President of the Public Health Foundation of India.
If some urban areas approach the immunity of the herd, where this threshold is, and also limit the transmission through masks and physical distancing and therefore see cases of fall, perhaps the low speed at which the virus spreading through rural India may help explain sunken figures, Reddy suggested.
Another possibility is that many Indians are exposed to various diseases throughout their lives (cholera, typhoid and tuberculosis, for example, are prevalent) and this exposure can encourage the body to get a stronger and more initial immune response. in the face of a new virus.
“If the COVID virus can be controlled in the nose and throat, before it reaches the lungs, it does not become so serious. Innate immunity works at this level by trying to reduce viral infection and prevent it from reaching the lungs, ”said Jameel, of Ashoka University.
Despite the good news in India, the rise of new variants has added another challenge to efforts made here and around the world to control the pandemic. Scientists have identified several variants in India, including some that have been accused of causing new infections in people who already had an earlier version of the virus. But they are still studying the implications for public health.
Experts are considering whether the variants could lead to an increase in cases in the southern state of Kerala, which had previously been considered a plan to fight the virus. Kerala accounts for almost half of the current cases of COVID-19 in India. Government-funded research has suggested that a more contagious version of the virus could be played out and efforts to sequence its genome continue.
As the reasons for India’s success are unclear, experts are concerned that people will lower their guard. Much of India has already returned to normal life. In many cities, markets are moving, roads are crowded and restaurants are almost full.
“With the reduction in figures, I think the worst of COVID is over,” said MB Ravikumar, an architect hospitalized last year and recovered. “And we can all breathe a sigh of relief.”
Maybe not yet, said Jishnu Das, a health economist at Georgetown University who advises the state of West Bengal on treating the pandemic.
“We don’t know if that will come back after three to four months,” he warned.