Covid 19 coronavirus: India's mysterious drop in virus infections

A health worker prepares to administer a Covid-19 vaccine at a hospital in New Delhi, India. Photo / AP

There were grave fears for the world's second most populous nation as Covid-19 swept through India last year.

Nearly 100,000 new infections were reported each day when the virus took hold of the nation of 1.3 billion people in September.

At that point, India was on course to overtake the USA and record the biggest case toll of cases worldwide.

As deaths began to soar in tandem with the rising cases, experts warned the consequences were to be dire for the developing nation as Covid-19 tore through India's infamously overcrowded cities.

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It looked as if their fears were realised in November when official figures showed 90 per cent of New Delhi's critical care beds with ventilators were filled.

However, things began to change unexpectedly and suddenly. Cases started to plummet overnight and the number of daily deaths linked to the disease soon followed.

A health worker checks the temperature of a passenger at Bandra train station in Mumbai, India. Photo / AP

Now the country is reporting about 11,000 new cases a day. Despite new variants causing massive surges in cases in other countries in recent months, India's cases have continued to drop consistently since September.

Large parts of India have already returned to normal life. In many cities, markets are bustling, streets are crowded and restaurants are full.

India does not have the testing capabilities of some developed nations, and its huge population poses significant issues for that capacity — so the actual number of cases is likely to be much higher than the number of confirmed cases.

There are also questions about how the country's is counting virus deaths, so they are likely to be higher than the official figures suggest.

However, if we look at the official statistics from New Delhi hospitals, it is clear we're not just seeing a failure in testing.

People wait outside a health center to get tested for COVID-19 in New Delhi, India. Photo / AP

On the last count on Thursday, critical care beds in the city were just 16 per cent full.

The virus has still devastated parts of the nation, with nearly 11 million cases reported and over 155,000 deaths. But for comparison, the US has recorded over 28 million cases and almost half a million deaths from the virus — from a population of 328.2 million — and some 2.4 million people have died worldwide.

For that reason, experts have been left perplexed by India's sudden drop — seen in almost every region of the nation — with some suggesting it may have reached herd immunity or that Indians may even have some pre-existing protection from the virus.

Vaccines have so far been ruled out as a reason alone as the country's jab program didn't begin until January — although this is expected to brighten the outlook even further.

The Indian government is taking some of the credit, saying its tough rules on mask-wearing and heavy fines for those that break them in some cities are at least partly responsible.

A health worker takes a swab sample of a commuter to test for COVID-19 at a train station in Mumbai, India. Photo / AP

However, experts have shot this down as a reason, saying that the level of mask wearing fluctuates wildly from area-to-area in India, meaning it would not account for cases dropping nationally in such a uniform way.

Vineeta Bal, who studies immune systems at India's National Institute of Immunology, told Sky News that some large areas may have reached herd immunity.

Herd immunity happens when a large portion of a community becomes immune to a disease through vaccination or through the mass spread of the disease.

However, a nationwide antibody screening by national health agencies found that one in five Indians had caught the virus before vaccinations had begun — and that rate rose to 50 per cent of the population in some major cities — which is far below the estimated 70 per cent necessary for herd immunity.

This makes some experts believe that herd immunity is not responsible for the dramatic drop in cases.

"There is no region in the country which can be deemed to have attained herd immunity, though small pockets may exist," Dr K Srinath Reddy, president of the Public Health Foundation of India, a Delhi-based think tank, told the BBC.

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Another theory is that many Indians are exposed to such a wide variety of diseases and germs throughout their lives — like cholera, typhoid and tuberculosis — that their bodies are more resilient in their immune response to new illnesses like coronavirus.

"If the Covid virus can be controlled in the nose and throat, before it reaches the lungs, it doesn't become as serious. Innate immunity works at this level, by trying to reduce the viral infection and stop it from getting to the lungs," Dr. Shahid Jameel, who studies viruses at India's Ashoka University, told the Associated Press.

Despite India's mysterious success story in controlling the virus so far, there are fears the population as a whole remains vulnerable, particularly in the face of new variants.

New research suggests that people infected with one strain of the virus could be reinfected with a new strain.

Yesterday, The Times of India reported the South African and Brazilian mutant strains of coronavirus have entered the nation, and that 187 Indians have tested positive to the UK variant so far.

With the reasons behind nation's success unclear, experts are concerned that Indians will let their guard down — as large parts of India have already returned to normal life.

"Danger still lurks around the corner," Dr Reddy told the Associated Press.

"If the mutants enter and they start rising in numbers, and particularly other susceptible sections of our population who have not been infected so far or have not been vaccinated so far get affected, then we can still have a sudden spike in the cases."