Does Your Blood Type Affect COVID-19 Risk? Research Suggests There’s a Chance
In this series of posts, we will talk about the biological side of COVID-19, as understood by a high school student. Click here to view previous articles.
Researchers have already identified several characteristics, commonly referred to as risk factors, such as underlying respiratory conditions and older age that increase the probability of COVID-19 illness. One potential risk factors, however, that has sparked a discussion in the medical community is ABO blood type.
A genetic study conducted by the biotech giant 23andMe suggests that there is a correlation between blood type and the probability of individuals testing positive. According to their data, which consisted of over one million participants, certain blood types reported a higher positivity rate. The following table represents the percent of respondents reporting a positive COVID-19 test, and has been adjusted for age, sex, body mass index, race, ethnicity, and co-morbidities (presence of multiple diseases/conditions).
As seen in the data, type O respondents reported a positivity rate of 1.3%, type A respondents reported a positivity rate of 1.4%, and type B and AB respondents reported a positivity rate of 1.5% each.
In order to further eliminate outside variables and better understand the relationship between blood type and acquiring the infection, the researchers restricted the data sample to only those individuals with a high probability of exposure. This sample primarily included essential workers.
When only observing potentially-exposed individuals, those with type O blood were approximately 20% less likely to report a positive test, as seen in the graph above. It is well known that blood type plays a role in various other diseases, for example, individuals with type B blood are more succestible to pancreatic cancer, so it is certainly possibile for blood type to play a role in COVID-19. As explained by the researchers in a post on the 23andMe blog, “The significance of this association may be related to the role of blood clotting complications in the cases of people with COVID-19”. These results seem to also be backed up by Douglas A. Drevets, University of Oklahoma’s chief of infectious diseases. However, he also made sure to mention that these results don’t “mean people with Type O blood will not get infected. It just means they’re 20% less likely to get infected than they might have been otherwise”.
While the correlation between blood type and positivity rate is generally accepted, it is still disputed whether blood type influences the severity and mortality rate of COVID-19 in patients. One of the first research papers claiming that blood type influences severity was published by Italian and German researchers in early June, who claimed that blood group A had a higher risk whereas type O blood had protective characteristics when compared to other blood groups. On the other hand, in an article published by Harvard Medical School later in July, the researchers strongly opposed the association between COVID-19 severity and blood type. The following excerpt is from an article summarizing their data analysis:
The large retrospective review showed no significant connection between blood type and worsening of the disease, between blood type and the need for hospitalization, positioning requirements for patients during intubation, or any inflammatory markers… Inflammation is a particularly important finding because prevailing scientific thought is that COVID-19 wreaks havoc on the body through systemic inflammation, which can lead to morbidity and death… We found, however, that inflammation markers remained similar in infected patients regardless of their blood type.
Regardless of the correlation, blood type is still a tenuous variable in the likelihood of testing positive, and certainly does not mean an O blood type will shield you from contracting the virus. What really matters in how much of the virus you really come into contact with. As perfectly put into words by Drevets, “If you encounter, say 1,000 particles, and you’re just at that level of infection, you may or may not get infected…If you encounter a million, the odds are highly likely that you will get infected and have a much more severe course.” As a result, it is crucial to minimize high risk situations and follow health guidelines recommended by professionals.
References
“23andMe Finds Evidence That Blood Type Plays a Role in COVID-19.” 23andMe For Medical Professionals, 10 June 2020, medical.23andme.com/23andme-finds-evidence-that-blood-type-plays-a-role-in-covid-19/.
@sheridan_kate, Kate Sheridan, et al. “23andMe Research Finds Possible Link between Blood Type and Covid-19.” STAT, 16 Sept. 2020, www.statnews.com/2020/09/14/23andme-study-covid-19-genetic-link/.
AYLIN WOODWARD, Business Insider. “Your Blood Type May Affect COVID-19 Risk, But It’s No Kind of Protection, Experts Say.” ScienceAlert, www.sciencealert.com/early-research-suggests-type-o-blood-might-give-a-slight-advantage-against-covid-19.
Affairs, Mgh News And Public. “COVID-19 and Blood Type.” COVID-19 and Blood Type | Harvard Medical School, 17 July 2020, hms.harvard.edu/news/covid-19-blood-type.
“Assessing Risk Factors for Severe COVID-19 Illness.” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, www.cdc.gov/coronavirus/2019-ncov/covid-data/investigations-discovery/assessing-risk-factors.html.
“COVID-19 and Blood Type: What’s the Link?” Los Angeles Times, Los Angeles Times, 9 July 2020, www.latimes.com/science/story/2020-07-09/link-between-covid-19-and-blood-type.
“Covid-19 Updates.” Blood Type and COVID-19? | MIT Medical, medical.mit.edu/covid-19-updates/2020/07/blood-type-and-covid-19.
Evans, Katy. “More Evidence That Your Blood Type Affects Your Risk Of Covid-19.” IFLScience, IFLScience, 28 Sept. 2020, www.iflscience.com/health-and-medicine/more-evidence-that-your-blood-type-affects-your-risk-of-covid19/.
“Genes, Blood Type Tied to Risk of Severe COVID-19.” National Institutes of Health, U.S. Department of Health and Human Services, 18 June 2020, directorsblog.nih.gov/2020/06/18/genes-blood-type-tied-to-covid-19-risk-of-severe-disease/.
“Genes, Blood Type Tied to Risk of Severe COVID-19.” National Institutes of Health, U.S. Department of Health and Human Services, 18 June 2020, directorsblog.nih.gov/2020/06/18/genes-blood-type-tied-to-covid-19-risk-of-severe-disease/.
Latz, Christopher A, et al. “Blood Type and Outcomes in Patients with COVID-19.” Annals of Hematology, Springer Berlin Heidelberg, Sept. 2020, www.ncbi.nlm.nih.gov/pmc/articles/PMC7354354/.
Ogle, Abigail. “Health Expert Explains How Blood Type Plays a Role in COVID-19 Infection.” KOCO, KOCO, 29 Sept. 2020, www.koco.com/article/health-expert-explains-how-blood-type-plays-a-role-in-covid-19-infection/34198770#.
Zietz, Michael, and Nicholas P Tatonetti. “Testing the Association between Blood Type and COVID-19 Infection, Intubation, and Death.” MedRxiv : the Preprint Server for Health Sciences, Cold Spring Harbor Laboratory, 11 Apr. 2020, www.ncbi.nlm.nih.gov/pmc/articles/PMC7276013/.
