Doctor Richard Anderson is a retired Professor of Microbiology.
When contemplating the effects of Covid-19, we would do well to meditate on California’s endemic Yellow-billed Magpies as a model of how nature works her relentless process of evolving life forms. About 180,000 of these beautiful birds previously mobbed various favorite sites in Modesto and throughout their limited California range. More than half died after West Nile Virus reached California in 2004.
Those virus-resistant survivors have now built back up to a population estimated between 90,000 and 110,000 individuals.
We humans are likewise the descendants of ancestors beset for millennia by bacterial, fungal, parasitic and viral epidemics. Smallpox, tuberculosis, polio, measles, chickenpox, influenza, and more have killed unknown billions—just consider the horrific Black Plague, which killed 50 million people in the 14th century. This is part of natural selection—epidemics without medicine.
When a new pathogen enters a susceptible human population, it may be horrifically lethal, as evidenced by the population collapse of New World Native Americans after contact with Columbus and other invaders.
Also, in the 1980s, without treatment, nearly all AIDS patients died within 2 years of diagnosis. Yet there are resistant humans. Magic Johnson has lived 29 years after announcing he was infected with HIV. Many long-term survivors have two mutant receptor genes needed by HIV to infect cells, called the CCR-5 coreceptor.
Creating “herd immunity” to pathogens is an “expensive” process—the cost is often life itself. The SARS-CoV-2 virus is inflicting this winnowing process on us right now. A new pathogen evolves; the more susceptible hosts become sick and die; individuals with the best immune responses and other responses survive to reproduce their genes. Having the right HLA genes (Human Leukocyte Antigens) can be the decisive advantage to survival. These genes are being investigated vigorously regarding our Coronavirus pandemic.
The human COVID-19 death rate is estimated as 1% to 7%, depending on country and data analysis. We are desperately enforcing stay at home rules to give us time to develop antivirals and, ultimately, a vaccine. Without them, nature takes its toll.
Some demonstrators are now demanding an “early reopening” of the economy. Ammon Bundy has blurted out “I want the virus now!” so he can deal with it while he is young and strong. Some declare that unemployment kills people too. Others advocate, “Faith not Fear.”
Still others degrade the importance of the coronavirus, claiming that every year influenza kills 3,000 to 50,000 of us anyway, and we don’t shut down the economy for that. But as of 4/24/20, more than 50,000 US residents have died from the coronavirus over a few short months. Should we reopen now?
We all should remember the message of the magpie. Without effective drugs and vaccines, nature is a harsh but always reliable teacher. If only 1% of COVID-19 infected people die, up to 3,300,000 US deaths can be expected if all of us are exposed to the virus. We must delay exposure as much as possible until effective anti-viral drugs and/or a vaccine are available.
Sources and further reading:
Early Impact of West Nile Virus on the Yellow-Billed Magpie (Pica Nuttalli)Scott P. Crosbie, Walter D. Koenig, William K. Reisen, Vicki L. Kramer, Lauren Marcus, Ryan Carney, Edward Pandolfino, Ginger M. Bolen, Lizette R. Crosbie, Douglas A. Bell.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2892874/
The Auk, Volume 125, Issue 3, 1 July 2008, Pages 542–550, https://doi.org/10.1525/auk.2008.07040
Pica populations: https://www.iucnredlist.org/species/22705874/131399674
120 papers on Google Scholar for “HLA Antigens + SARS CoV-2” since 2016
Local cases & deaths http://www.schsa.org/PublicHealth/pages/corona-virus/