COVID19 pandemic: is the SARS-COV2 Virus colorblind?
Dr. Shuchi Anand, Stanford University, Dr. Dorairaj Prabhakaran, Center for Chronic Disease Control & Dr Ramesh Byrapaneni Endiya Partners
We are inundated by metaphors of war on a daily basis currently, compelled to participate in a fight against an undiscerning virus that does not heed geographic boundaries or salary brackets.
Yet, as the COVID19 pandemic continues, we see clearly see the SARS-COV2 virus targeting the elderly and the chronically ill. News of hidden deaths in nursing homes and images of elderly grandparents saying their last lonely goodbyes on the telephone will mark our historical records. Nearly all COVID19 deaths are occurring among individuals with at least one prior medical comorbidity (https://jamanetwork.com/journals/jama/fullarticle/2764365).
But what isn’t as immediately clear is whether the virus is also targeting specific races or ethnic groups. Is there a racial/ethnic difference in susceptibility to serious illness from SARS-COV2? On the one hand, reports from the U.K. and U.S.—among some of the most racially and ethnically diverse countries in the world—highlight a disproportionate death toll in racial and ethnic minorities. On the other hand, the relatively low numbers of infection and death toll in South Asia and South Africa has raised theories about temperature, innate immunity or BCG vaccination as possible protective factors.
The disproportionate rates of death in the African American individuals in the U.S. has garnered significant media attention, and rightly so. The starkest disparity data come from Michigan which is a predominantly Caucasian state: 41% of COVID19 deaths in the state are occurring in African Americans, when they only make up 14% of the state’s population (https://www.michiganradio.org/post/michigan-passes-2000-covid-19-deaths). Similarly, much higher risk for death is reported among Black Britons, who are experiencing the highest per capita death rate in the UK despite the minority groups being younger than the white Britons. (https://www.ifs.org.uk/inequality/chapter/are-some-ethnic-groups-more-vulnerable-to-covid-19-than-others/),
The U.S. Asian and Hispanic minorities are not necessarily at higher risk, with Asian residents having lower than expected data rates in some states (https://www.cdc.gov/coronavirus/2019-ncov/need-extra-precautions/racial-ethnic-minorities.html ). While in the U.K., Pakistani and Indian minorities experienced higher—in the case of Pakistani minorities, nearly 3-fold higher—risk for death compared with white Britons the disparity in death rates between these two genetically similar groups in the U.S. and U.K. may reflect the difference in their socio-demographic status and concentration in urban areas. Occupational status is felt to be a key difference as well; more of the Asian minorities living in the U.K. are employed in health care support services
If poverty and population-density render individuals more vulnerable to serious illness, however, then countries such as India and South Africa would have been expected to have starkly higher death tolls. Any death from COVID19 is potentially a preventable death but given the previously unimaginable numbers we are seeing from Italy, Spain and the U.S., the relative sparing of these countries is remarkable. Some in popular media have invoked genetic programming to higher immunity (https://www.downtoearth.org.in/news/health/covid-19-do-indians-have-higher-immunity-to-novel-coronavirus-70322), but this is unlikely to apply to a previously uncirculated virus. We are all vulnerable, and in the vast majority of individuals with critical illness, the question is not whether the immune system is reacting sufficiently, is it that there is too much of an immune response—the so-called cytokine storm.
So what else could be at play?
Well the harsh lockdowns imposed in both countries are a first and foremost unifying explanation. In South Africa, lockdowns included bans on sales of alcohol to discourage any formal or informal gatherings; in India, all public transportation halted, and streets were patrolled for people traveling without proof of essential role. The age demographics of both countries also skew much younger than in the highest affected countries.
We also know that while hotter temperatures don’t prevent the virus from catching a foothold in a region (see the example of New Orleans in the U.S., or Sydney, Australia), strong data do demonstrate that the virus’ longevity on surfaces is affected by temperature. So while not necessarily rendered innocuous, the virus could still lose its edge in hotter environments, and the ability of a single infected person to infect additional contacts (termed the R naught) could be lower.
A third theory, one which has already spurred two clinical trials, is the possibility that BCG vaccination in early childhood allows for protection against respiratory co-infections and thus offers some protection to death from SARS-COV2 (https://www.medrxiv.org/content/10.1101/2020.03.24.20042937v1.full.pdf+html ). Authors of a review included in appraisals done by the World Health Organization present ecological support that for the hypothesis that countries with nationalized mandatory BCG vaccination have experienced lower rates of death from COVID19. Based on these data, Australia has launched a trial in which upto 4000 health care workers will be enrolled and randomized to BCG vaccination, and its effects on their risk for COVID19 determined (https://clinicaltrials.gov/ct2/show/NCT04327206) .
In the era of the COVID19 pandemic, much still remains a mystery. It may be that in the highest affected countries, the virus is indeed colorblind, but the socio-economic conditions which render a person susceptible to serious illness are not. What is clear is that we will learn much about SARS-COV2 and be able to prepare better for the next such novel infection by evaluating the current one through the lens of its effects on different races, ethnic groups and geographic regions.
Opinions expressed solely are our own and do not express the views or opinions of the organizations we are associated with.
References:
https://www.apmresearchlab.org/covid/deaths-by-race
https://www.cdc.gov/coronavirus/2019-ncov/need-extra-precautions/racial-ethnic-minorities.html
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