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Too early to say Indians have T cell-mediated protection against Covid infection, says ICMR

Health Secretary Rajesh Bhushan says Covid is spreading to new areas in India but 66 per cent of cases continue to be in 50 districts and 82 per cent in 10 states.

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New Delhi: Although the country’s Covid-19 cases and deaths per million population are among the lowest in the world, it is too early to say whether Indians have some kind of innate protection against the SARS-CoV-2 virus, especially of the kind afforded by T lymphocytes of the human body, said the ICMR chief Tuesday.

“There are some hypotheses that prior exposure to coronaviruses — there are six of them — grants some T-cell-based immunity. But we cannot say that our numbers are low in India because of that. It is too early to come to such a conclusion,” Dr Balram Bhargava, director general, Indian Council of Medical Research (ICMR), told ThePrint on the sidelines of the weekly Covid-19 briefing.

At the briefing, he said the findings of the first sero survey conducted by the ICMR were likely to be published in the Indian Journal of Medical Research in the next two weeks after being peer reviewed. However, he also made the point that while sero surveys assess antibodies, they cannot estimate the T-cell response of the body.

In a recent study in The Nature, researchers argued that past encounters with endemic coronaviruses could have primed some people to thwart a SARS-CoV-2 infection better because of some attributes in their T Lymphycyte, a class of white blood cells. This and some other findings have now led to the hypothesis that while the disease is infectious, not everybody is equally vulnerable to it.

Bhargava also said that there is very little difference in the three strains of the virus currently circulating in the country — from Wuhan, Italy and Iran returnees.

“The virus strain was examined at the National Institute of Virology and we found that they were pretty similar — 99.96 per cent. There is literature to say some mutation is going on, but very mild. For a virus to mutate and become completely different takes 10-50 years. So far there have been no major mutations,” he said.

Also read: T cells, B cells and the range of the human body’s immune response — A simple decoder

‘No underestimation of deaths’

Health Secretary Rajesh Bhushan ruled out any chances of underestimation of Covid deaths citing the fact that a very high proportion of the tests have happened in cities like Delhi, Mumbai and Chennai, where both registrations of deaths and medical certification of deaths are way higher than the national average.

“When we say underreporting of deaths in Covid, it is a mere conjecture. In the initial phase, the ministry issued clear guidelines keeping in view WHO guidelines … on how to report deaths. We found initially some states not reporting Covid deaths of co-morbid patients. So we clarified that. The second issue (is) that most deaths have come from specific urban areas, where even during normal times, death registration is very high.

“In Maharashtra, death registration is 93 per cent, it is 100 per cent in Tamil Nadu and Delhi. The national average is 80 per cent death registration. The percentage of medically certified deaths of the total registered deaths is 22 per cent nationally. In Maharashtra, it is 67 per cent, in Delhi it is 69 per cent, in Tamil Nadu it is 85 per cent. In such a scenario, to say that deaths are being underreported is thoroughly unjustified,” Bhushan said.

In recent days, there have been a series of reports in international media on the alleged underreporting of Covid deaths in India. A group of over 230 public health professionals, epidemiologists and activists sought the release of data on all registered deaths in India since 2018.

Broadly 68 per cent of Covid deaths in India are males. Of the total deaths, 50 per cent deaths are of people aged 60 years and 37 per cent are of people aged 45-60 years.

Also read: Delhi, Mumbai & Chennai infection rates dip below 1, India’s overall R value now at 1.16

‘Positivity in some states a cause for worry’

Bhushan said that the virus is spreading to new areas in India but 66 per cent of cases continue to be in 50 districts and 82 per cent in 10 states.

India has been pushing its testing numbers intermittently over the past few days and aims to eventually to test 10 lakh cases daily. However, Bhushan said in the briefing, “Last week India’s positivity was 11 per cent. This means that there are some states where the positivity rate remains above 10 per cent and these need more attention.”

Bhargava clarified that the two situations in which a country needs to push up testing are when it is below the WHO prescribed target of 140 tests per lakh population or if the positivity rate is above 10 per cent. India’s daily positivity rate was above 10 per cent the last three days, but fell to 7.8 per cent Tuesday.

On rapid antigen tests (RAT), Bhargava said about 25-30 per cent of the tests conducted are RAT. If a symptomatic patient tests negative in RAT, their samples are verified in a RT-PCR test.

Defending the strategy, the ICMR head said, “In the first five days of infection, chances of an RT-PCR coming negative are very high too.”

‘Find vaccine both science & socio-cultural matter’ 

The availability of a Covid vaccine, Bhargava said, is not just a matter of science but also socio-cultural engagements.

“There is no specific drug or vaccine available yet. (The) need for a vaccine is great and urgent. But there is a dilemma. The pandemic is progressing rapidly. Developing a vaccine takes time not just from the science aspect but also social, cultural and regulatory aspects,” he said.

“We have three vaccines in trials. The first is the Bharat Biotech vaccine that completed Phase I study in 11 sites and started on Phase II. For the DNA vaccine of Zydus, India has completed Phase I and moved to Phase II in 11 sites. The third vaccine got approval yesterday (Monday) and is the recombinant Oxford vaccine that was approved for Phase II and III trials that are starting in 17 sites,” Bhargava said.

The immediate concerns after a vaccine is developed are fair distribution, cold chain, stockpiling and training of people, he added.

Also read: 800 new deaths in 24 hours, India infection rate down to 7.8%, daily testing crosses 6.6 lakh


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