New Study Questions Blood Type's Effect on COVID-19 Susceptibility

Near the beginning of the pandemic, several studies suggested that persons with type-A blood were more susceptible to contracting COVID-19 and that persons with type-O blood were less susceptible. Subsequent studies demonstrated a wide variety of findings, some tying blood type to increased susceptibility but not severity, and others finding no association at all.

In a new case-controlled study, conducted at Intermountain Healthcare, researchers analyzed hospital and clinic databases for individuals who tested positive for COVID-19 between March 3, 2020, and November 2, 2020.¹ Additionally, these individuals needed to have a recorded blood type on file.

A total of 107,796 persons across 24 hospitals and 215 clinics were included in the study. Overall, 11,468 of these patients tested positive for COVID-19.¹ Researchers noted that while other demographic determinants played a role in hospitalization, intensive care unit (ICU) admission, and viral positivity, blood type was not associated with susceptibility to or severity of COVID-19.¹

Table. Breakdown of Blood Type Percentage in Positive and Negative COVID-19 Results¹

Compared with type-O blood, individuals with type-A blood did not have an increased occurrence of viral positivity (OR, 0.97 [95% CI, 0.93-1.01]; p=0.11), hospitalization (OR, 0.89 [95% CI, 0.80-0.99]; p=0.03), or ICU admission (OR, 0.84 [95% CI, 0.69-1.02]; p=0.08).¹ This lack of association was also found when comparing types B and AB.¹

The authors of the study stated that “given the large and prospective nature of our study and its strongly null results, we believe that important associations of SARS-CoV-2 and COVID-19 with ABO groups are unlikely and will not be useful factors associated with disease susceptibility or severity on either an individual or population level.”¹

—Audrey Amos, PharmD

Reference

1. Anderson JL, May HT, Knight S, et al. Association of sociodemographic factors and blood group type with risk of COVID-19 in a US population. JAMA Netw Open. 2021;4(4):e217429. doi:10.1001/jamanetworkopen.2021.7429