On Aug. 26, 2021, Oregon Health & Science University (OHSU) announced a laboratory study from found that blood serum drawn from people previously vaccinated or naturally infected show ‘significantly reduced’ defense against two widely circulating variants of the novel coronavirus SARS-CoV-2.

Researchers found two variants of concern – B.1.1.7 originating in the U.K., and B.1.351 originating in South Africa – show reduced neutralization by antibodies in the blood of almost 100 people who were vaccinated with the Pfizer vaccine or previously infected by the virus. In the case of the B.1.351 variant, researchers measured a nine-fold reduction in effectiveness compared to the original SARS-CoV-2 virus.