SARS-CoV-2 Variant from South Africa: 1st U.S. Cases / Efficacy of Pfizer-BioNTech Vaccine / Case Spike in Africa
South Carolina officials on Thursday reported two cases of SARS-CoV-2 infection with the variant first detected in South Africa, known as B.1.351. The two cases — the first identified in the U.S. — are not connected, the state’s public health department said in a news release. In addition, neither person has a known relevant travel history.
In related news, the efficacy of the Pfizer-BioNTech COVID-19 vaccine may be only slightly reduced against B.1.351, according to anindustry-supported, in vitro study posted on the preprint server bioRxiv.
For the study, researchers engineered three SARS-CoV-2 viruses that had spike protein mutations seen in B.1.351 and B.1.1.7, the variant first detected in the U.K. They then tested sera from 20 vaccinated people for neutralization against these viruses and wild-type SARS-CoV-2.
Neutralization titers were roughly comparable for the three experimental viruses and wild-type virus. Of note, for one third of the serum samples, neutralization titers were half as high for the virus with B.1.351 mutations than for wild-type virus.
The researchers write, “The magnitude of the differences in neutralization [titers] against any of the mutant viruses in this study was small (0.81- to 1.41-fold), as compared to the 4-fold differences in hemagglutination-inhibition titers that have been used to signal potential need for a strain change in influenza vaccines.”
And finally, the World Health Organization has reported a recent spike in COVID-19 cases and deaths in Africa. In a news release, the agency noted that the B.1.351 variant “is predominant and powering record case numbers in South Africa and the sub-region.” The variant has been detected in Botswana, Ghana, Kenya, Mayotte, Zambia, and in at least 24 countries outside of Africa.
South Carolina health department news release
Study on bioRxiv (not peer-reviewed)