Dear Reader:

Worldometer (Aug 19): More than 22.4 million cases and more than 787 thousand Covid-19 deaths worldwide. More than 5.6 million and more than 175 thousand deaths in the U.S. Almost 44 thousand new cases and 1,358 deaths yesterday in the U.S.

More than 3.4 million cases and 110,171 deaths in Brazil. More than 48 thousand new cases and 1,365 new deaths yesterday in Brazil.

More than 2.8 million cases and 53,994 deaths in India. More than 65 thousand new cases and 1,089 new deaths yesterday in India.

I posted about the following article yesterday, and that post is awaiting moderation. (I am okay if it doesn’t get reposted).

New York Times: What if herd immunity is closer than scientists thought? (Aug 17)- the way I understand it and elaborate on it:  eventually the coronavirus will not find enough vulnerable people to infect and it will fade out as an epidemic/ pandemic (the Ro, the Reproduction Number, will lessen significantly), and as I see it, we will end up with a situation where Covid-19 will be another  respiratory disease added to respiratory diseases that predated Covid-19 (most common are the the common cold and the flu).

The situation where there are not enough vulnerable individuals to keep the virus so infectious as to cause an epidemic is called “herd immunity”-=a certain percentage of a population either has been sick and produced antibodies against the virus (natural immunity), or they are vaccinated and therefore possess antibodies against the virus (artificial immunity).

Scientists suggested that 70% of the population needs to be immune in one of the two ways above, others say 50%, some say even less, so to achieve herd immunity.

But it is not that, for example, 70% or 50% of all the people of Bombay, or all of the people in New York City need to be immune so to reach herd immunity (the situation where the virus is no longer very infectious/ an epidemic). In Bombay 51-58% of the population in the city’s poorest neighborhoods have been sick with Covid-19 and had developed antibodies for the virus. On the other hand, 11-17% of the people elsewhere in the city were sick and developed antibodies. Different percentages of immune people make herd immunity in the different neighborhoods.

Another example: 68% of the people who visited a clinic in the Corona-neighborhood in Queens had antibodies for the virus, but only 13% of the people visiting the Cobble Hill section of Brooklyn had antibodies for the virus.

The neighborhoods where people are closer to each other, where they are more socially active (multiple people living together in an apartment, people taking mass transportation, people getting together in bars or places of worship, etc.), the poorer their health (obesity, suffering from diabetes and other pre-existing conditions), and the lesser the sanitation and hygiene practices– the higher the percentage of people who need to be immune  needed so to achieve herd immunity.

When vaccines become available, it doesn’t make sense to uniformly vaccinate everyone. Governments should identify and immunize people according to neighborhoods: first vaccinate where the virus is most infectious (poorer neighborhoods), and then vaccinate people were the infection is lower (wealthier areas). This will benefit everyone, including the wealthier because people travel and so does the virus.

Problem is that the Covid-19 antibodies seem to last about 3 months, and so will the vaccine, so people may need to get vaccinated 4 times a year, I am guessing. Another problem is according to a recent poll in the U.S., a lot of people (more so,  the lesser educated and Republicans) say that they will not get vaccinated once a vaccine is available, or that they are not sure if they will.

anita

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