Updated: October 19, 2020 9:41:10 am
Devotees wearing masks to prevent the spread of coronavirus walk to a Kali temple in Jammu (AP)
The reasons for the continued decline in the number of coronavirus infections since last month have not been clear. The numbers have dropped dramatically, although travel restrictions have eased, economic and other activities have resumed, and normalcy has largely returned.
There has also been no reduction in the number of tests, nor has the prevalence of the disease in the population reached a stage where “herd immunity” should be taken into account. The use of masks and physical distancing are far from universal.
the government appointed scientific committee It has not explained the possible reasons for the decrease in the number of coronavirus. But two of its members offered information about what could be happening.
“A recent case study from Andhra Pradesh and Tamil Nadu published in the journal Science a few weeks ago showed that almost 70 percent of infected people did not transmit the disease to other people. The virus spreads only through a small group of people referred to as super-spreaders, ”committee member Professor Manindra Agrawal told The Indian Express.
These super-spreaders, Professor Agrawal said, are more likely to become infected during the initial phase of the epidemic. “So it is possible that the super-spreaders have already been infected and become immune. And as we have seen, very few of the others transmit the disease. This could be a possible reason for what we are seeing right now, ”he said.
Super-spreaders are infected people who infect large numbers of others. The study Agrawal was referring to had been based on data from more than 85,000 confirmed infections in Andhra Pradesh and Tamil Nadu as of August 1, and nearly 6 lakh of his contacts who were identified and traced. It is the largest study of its kind so far.
Travelers wearing face masks as a precaution against coronavirus wait for a bus in Kolkata (AP Photo / Bikas Das)
The study found that more than 60,000 of the 85,000 confirmed infected people never transmitted the infection to other people. On the other hand, a very small number, less than 10 percent, accounted for more than 60 percent of secondary infections. These were the super-spreaders, each of which transmitted the infection to perhaps 20, 30, 40 or even more people.
Professor Agrawal noted that the super spreaders didn’t have any special qualities aside from the fact that they were interacting with more people than most others. A vegetable vendor, for example, is likely to interact with many more people than the average assistant officer.
“Precisely for this reason, they are also likely to become infected early. If you remove super-propagators from the equation, the reduction in coronavirus numbers doesn’t seem that surprising, “he said.
Professor Gagandeep Kang, an infectious disease expert and professor at Christian Medical College, Vellore, said it was not unexpected to find that the disease was actually spreading through a very small number of infected people. Professor Kang, who is also a member of the committee that reported its findings on Sunday, offered another possible reason for the numbers to drop.
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A healthcare worker takes a swab sample for the Covid19 test in New Delhi.
“Look, we all have varying degrees of contact with people. We can have 10-15 people that we interact with on a very regular basis, then another larger group of people that we might meet occasionally, and an even larger group that we rarely interact with. During the restrictions, we would be interacting primarily with people within our inner circle. Any infection that had to occur in that small circle of contacts could have already happened. Once that has happened, the numbers are expected to decline. For new infections to occur, people must begin to interact with larger assemblages or complete strangers, such as passengers on public transportation. That is just starting to happen, and I suspect that most of the infections we see now are the result of those kinds of interactions, rather than in closed groups, “said Dr. Kang.
“Everything related to the transmission of the virus depends on the nature and duration of our interactions with other people. And there are many things that we do not understand or cannot analyze due to the lack of adequate data. But this decrease in figures in the last month is not inexplicable. It can be explained if we have good data and information, ”he said.
Professor Agrawal noted that the current decline in cases in India was similar to what many European countries had experienced a few months ago.
A healthcare worker sorts the samples for the COVID-19 test. (Express photo by Amit Mehra / Archive)
“Take the case of Italy, for example. There, too, the prevalence of the disease had not become so widespread that we could have started talking about herd immunity. But the cases had drastically decreased. What we are seeing now (in Italy) is a resurgence or a second wave. But not every country or region needs to go through a second wave of infections. If we are cautious and move forward over the next few months, we can hope for a better situation next month, ”he said.
Professor Kang said that, aside from festivals, the approaching winter and the resulting increase in air pollution could also be cause for concern.
“We still do not fully understand the correlation of the coronavirus epidemic with cold weather. But there is a seasonality associated with the spread of other types of viruses and infectious diseases, and based on that experience, it would not be entirely out of place to suggest that the spread of the coronavirus could increase during the winter. We have to be careful. Air pollution could also be a cause for concern. Bad air is already a big reason for respiratory illnesses and the coronavirus can complicate things even more, ”he said.
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