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NEW DELHI (AP) – When the coronavirus pandemic took hold in India, there were concerns that it could sink the fragile health system of the second most populous country in the world. Infections soared dramatically for months and at one point India looked like it could overtake the United States as the country with the most cases.
But infections began to drop in September, and now the country is reporting around 11,000 new cases a day, up from a peak of nearly 100,000, leaving experts perplexed.
They suggested many possible explanations for the sudden drop – seen in almost every region – including the fact that parts of the country may have achieved herd immunity or that Indians may have pre-existing protection against the virus.
The Indian government has also partly attributed the drop in cases to wearing a mask, which is compulsory in public in India and violations carry heavy fines in some cities. But experts noted the situation is more complicated as the drop is uniform even though mask compliance is declining in some areas.
It’s more than just an intriguing puzzle; Finding out what’s behind the drop in infections could help authorities control the virus in the country, which has reported nearly 11 million cases and more than 155,000 deaths. Some 2.4 million people have died around the world.
“If we don’t know the reason, you might unknowingly do things that could lead to an outbreak,” said Dr Shahid Jameel, who studies viruses at Ashoka University in India.
India, like other countries, lacks many infections, and there are questions about how it counts virus deaths. But the pressure on hospitals across the country has also eased in recent weeks, another indication that the spread of the virus is slowing. When recorded cases exceeded 9 million in November, official figures showed that nearly 90% of all intensive care beds with ventilators in New Delhi were full. As of Thursday, 16% of those beds were occupied.
This success cannot be attributed to vaccinations since India only started administering vaccines in January – but as more people get vaccinated, the outlook should be even better, although experts are also concerned about the variants identified in many countries which appear to be more contagious. and make some treatments and vaccines less effective.
One possible explanation for the drop in cases is that some large areas have achieved herd immunity – the threshold at which enough people have developed immunity to the virus, by falling ill or getting vaccinated, that the The spread is starting to ease off, said Vineeta Bal, who studies immune systems at India’s National Institute of Immunology.
But experts have warned that while herd immunity in some places is partly responsible for the decline, the population as a whole remains vulnerable – and must continue to take precautions.
This is especially true because new research suggests that people who have fallen ill with some form of the virus may be able to become infected again with a new version. Bal, for example, pointed to a recent survey in Manaus, Brazil, which estimated that more than 75% of people there had antibodies to the virus there in October – before cases resumed in January.
“I don’t think anyone has the final answer,” she said.
And, in India, the data is not so dramatic. A nationwide antibody test by Indian health agencies estimated that around 270 million, or one in five Indians, had been infected with the virus before the start of vaccinations – that’s well below the rate of 70% or more which experts believe could be the threshold for the coronavirus, although that is not certain.
“The message is that a large portion of the population remains vulnerable,” said Dr Balram Bhargava, who heads India’s leading medical research body, the Indian Council for Medical Research.
But the survey offered another glimpse of why infections in India may be declining. It showed that more people had been infected in India’s cities than in its villages, and that the virus was moving more slowly through the rural hinterlands.
“Rural areas have less crowd density, people work more in open spaces and houses are much more ventilated,” said Dr K. Srinath Reddy, President of the Public Health Foundation of India.
If some urban areas are getting close to herd immunity – wherever that threshold is – and also restrict transmission through masks and physical distances and therefore see declining cases, then maybe the low speed at which the virus is crossing rural India may help explain the falling numbers, suggested Reddy.
Another possibility is that many Indians are exposed to a variety of illnesses throughout their lives – cholera, typhoid, and tuberculosis, for example, are prevalent – and this exposure can cause the body to develop an initial immune response. stronger to a new virus.
“While the COVID virus can be controlled in the nose and throat, before it reaches the lungs, it doesn’t get as serious. Innate immunity works at this level, trying to reduce the 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 here and around the world to bring the pandemic under control. Scientists have identified several variants in India, some of which 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 variants could lead to an increase in cases in the southern state of Kerala, which had previously been heralded as a model to fight the virus. Kerala now accounts for nearly half of India’s current COVID-19 cases. Government-funded research has suggested that a more contagious version of the virus may be at play, and efforts to sequence its genome are underway.
With India’s reasons for success unclear, experts fear people are letting their guard down. Much of India has already returned to normal life. In many cities, markets are heaving, roads are crowded, and restaurants are almost full.
“With the numbers decreasing, I feel the worst of COVIDs is over,” said MB Ravikumar, an architect who was hospitalized last year and has recovered. “And we can all breathe a sigh of relief.”
Maybe not yet, said Jishnu Das, a health economist at Georgetown University who is advising the state of West Bengal on managing the pandemic.
“We don’t know if it will come back after three to four months,” he warned.
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The Associated Press’s Department of Health and Science receives support from the Department of Science Education at the Howard Hughes Medical Institute. The AP is solely responsible for all content.
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