Despite Progress, Protecting The Population Against Covid-19 Variants Remains Complex

More positive news comes from Pfizer and BioNTech this week as the latest results from their clinical trial data suggest that their vaccine protects against the more contagious B.1.351 variant initially detected in South Africa. The vaccine showed 100 percent efficacy in South Africa, where B.1351 is prevalent. Nine people in the study contracted Covid-19, all of whom were in the placebo group. However, these findings are limited as only 800 participants were enrolled in South Africa. Nonetheless, this is a very positive result and very different from the response of the AstraZeneca vaccine to the B.1.351 variant which recent studies showed only 10.4% efficacy against mild-to-moderate infections. The difference could be related to the amount of antibody titers produced by both vaccines, as although they are both reacting to the same antigen, the concentration of neutralizing antibodies is generally much higher in the Pfizer and Moderna vaccines than it is for the adenovirus vaccines.

However, the challenges in protecting the population against the ever-evolving variants remain complex, especially with regards to the unknown duration of protection. A study published this month takes a different approach to protection, asking the question do antibodies generated by infection with a variant protect against other strains.

The study used plasma collected from adults hospitalized with Covid-19 who were infected with two South African infection waves, with the second wave dominated by the B.1.351 variant. Sequencing demonstrated that infections in first wave plasma donors did not have any of the B.1.351 defining mutations, except for one with the E484K mutation in the receptor-binding domain.

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Originally published on Forbes on April 1st, 2021   


© William A. Haseltine, PhD. All Rights Reserved.