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Opinion

Covid-19: what you need to know today

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On Monday, the former head of the US Food and Drug Administration (FDA), Scott Gottlieb, said in an interview with CNBC that his estimate is that by the end of the year 30% of Americans would have been infected by the virus. Sars-CoV-2 coronavirus disease. That’s almost one in three Americans who will have some form of immunity to the virus. I know there is a lot of confusing research on this, especially when it comes to asymptomatic patients who have low viral loads, but I’m going to go with the most comprehensive research (Dispatch 207 from November 19 covered it) that most infected people have. at least six months of protection (of some kind) against Covid-19, with a non-negligible probability that this protection can last for years. Gottlieb added in the interview that he believes some states can have an infection rate of up to 50%.

  • Former US FDA chief Scott Gottlieb said in an interview with CNBC that his estimate is that by the end of the year, 30% of Americans would have been infected with the Sars-CoV-2 virus.

This bodes well for 2021, he suggested, and it’s easy to see why. If a third of the population is protected against the virus, there is a high probability that the chain of infection will be broken before too many people are infected. “It is reaching levels where this virus is not going to circulate as easily,” he told CNBC. The United States ended November with 13.6 million registered Covid cases. It could end the year with something between 17 and 18 million, at the current rate of growth in registered cases. If Gottlieb’s assessment is accurate, this number should actually be 100 million, meaning that for every recorded infection, about six are missing in the United States. That seems plausible and also highly probable. For the purposes of this column, I have assumed that to be true.

  • If a third of the population is protected against the virus in the US, there is a high probability that the chain of infection will be broken before too many people are infected.

India has seen almost 9.5 million cases of the coronavirus disease to date (it ranks second in terms of number of cases after the United States). A direct extrapolation of the Gottlieb constant (if you can call it that) might not make sense for a variety of reasons. India and the US are large and highly populated, but the differences between them in these two parameters remain stark. The United States has a population of 330 million; India, 1.3 billion (1.3 billion). The United States has a land area of ​​9.8 million square kilometers; India, 3.3 million square kilometers. The population density of the United States, based on these numbers, is 34 per square km; Almost 394 inhabitants of India per square km. Some of these factors suggest that the constant is higher in India; others, lower.

There are other factors at play as well: populations in some parts of India, like populations in parts of Africa, may have some protection against coronavirus disease due to previous infections with other coronaviruses; and the BCG vaccine, which almost all Indian children have received for decades, may offer some coverage against infection, or at least the intensity of infection.

In Room 158, on September 15, I submitted the assumptions that around 15% of the urban population in India and 5% to 7.5% of the rural population may have been infected with the virus. That number was based on antibody prevalence surveys conducted in many parts of the country. Those numbers have surely moved north. Metropolitan cities like Delhi and Mumbai are likely to have infection rates of around 20%; other Indian cities, 15%; and rural India 7.5%. The top 10 cities in India have a population of around 110 million. At an infection rate of 20%, they would have seen 22 million cases. India has a rural population of around 850 million people and an infection rate of 7.5% translates to around 64 million cases. The remaining 340 million urban dwellers would have suffered 51 million infections at an infection rate of 15%. That works out to a total of 137 million cases, which means that for every recorded infection, India is missing 15, which is also plausible. At the aggregate level, this translates into an overall infection (or exposure) rate of about 10%, although the number is likely to be much higher in some large cities and much lower in some remote rural areas.

Interestingly, and I did not assume numbers with this end in mind, although it may now seem so, with 137,000 deaths (the current death toll in India) and 137 million infections, the death rate from infections in India is 0.1%. , which some experts believe is a reasonable estimate of the death rate from Covid-19. Sure, it is likely (very likely) that the actual death toll in India is higher, but it is equally likely that the number of cases is as well.

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