Dear Reader:

1. A few items from my previous thread on Covid-19:

* There is no specific vaccine for Covid-19. But there is research regarding using modifications of the existing vaccines for tuberculosis and for  measles as non-specific vaccines for Covid-19.

* It is possible that a vaccine for Covid-19 will not be found. There are viral diseases for which vaccines were never found, ex. AIDS and the common cold.

* There are viral diseases for which there are vaccines that are very effective, ex. the measles, and there are viral diseases, such as the seasonal flu, for which vaccines are not very effective and need to be updated yearly (because of the rapid mutation rate of the influenza viruses).

* There is no specific antiviral drug for Covid-19. Antiviral drugs for other viral diseases  have been approved for use off label or as experimental drugs in the treatment of Covid, ex.: favipiravir, a flu antiviral drug, has been approved in Italy for experimental use against Covid-19.

* All viruses naturally mutate every time they replicate. One danger in not applying social distancing measures in a population, not hindering the spread of a virus, is that every time the virus infects an individual, it mutates; the more infections, the more mutations. Mutations can lead to more severe and more deadly virus strains.

The second wave of the Spanish flu a hundred years ago was way more deadly than the first wave because that virus mutated between the first and second wave into a deadlier form.

It is possible for a virus to mutate to a lesser deadly form- it may have happened in the SARS epidemic of 2002-03, which was declared contained by WHO in July 2003.

* Mortality rate for Covid-19 (as in other infectious diseases) is different in different parts of a country and the world, higher in populated areas such as New York City, and in community living settings such as nursing homes. The mortality rate of all diseases is higher where the health care system is inadequate.

The mortality rate of Covid-19 is different depending on age and pre-existing health conditions. In people younger than 50 years old, the mortality rate is less than 0.5%, but it’s more than 8% in people older than 70 years old (0.2% in ages 10-39, 0.4% in ages 40-49… 8% for 70-79, 14.8% for ages 80 and over).

Age is a huge factor determining Covid-19 mortality rate: Those 80 years and older have a mortality rate 74 times that of people 10-39 years old.

* Passive immunization, aka passive antibody therapy aka convalescent plasma therapy is used to treat patients in ICUs who are in serious or critical condition.

A most recent article in msn. com/ en-us/ news/ world/ coronavirus-spread-around-the-world-fast-new genetics-analysis-shows states that genetics researcher Balloux of the University College London Genetics Institute and colleagues pulled viral sequences from a giant global database that scientists around the world are using to share data (taken from more than 7,600 patients) .

They looked at samples taken at different times and from different places, and said they indicate that the virus first started infecting people at the end of 2019 (Many different studies have shown that CoV-2 originated in a bat, infected an intermediate animal and then jumped into humans. The first human cases were reported in Wuhan, China,  December 2019).

Viruses naturally make mistakes (aka mutate), every time they replicate themselves. These mutations can be used as a molecular clock to track a virus through time and geography. All corners of the globe show multiple mutations, and they are similar mutations, showing a common ancestor towards the end of 2019 (This rules out any scenario that CoV-2 circulated long before it was identified in Dec 2019 and the hope of herd immunity in some populations). Balloux estimates that at the most 10% of the global population has been exposed to the virus.

So far, “we cannot say whether SARS-CoV-2 is becoming more or less lethal and contagious,” Balloux said. Mutations are important when it comes to developing vaccines because the vaccines need to  target parts of the virus that are conserved — that do not change much over time.

anita

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