New SARS-CoV-2 Variant Could Evade Antibodies [View all]

[Klaralven]

In recent months, as the global COVID-19 pandemic rages on, new variants of SARS-CoV-2 have sparked concerns about whether existing vaccines will perform as well against the evolving virus as they did in clinical trials. Three preprints posted on bioRxiv on January 19 shed some light on this question, finding that serum from vaccinated people was able to neutralize a virus with some of the same mutations as one now-widespread variant, B.1.1.7, but was less effective in neutralizing strains mimicking another variant known as 501Y.V2.

One study investigated the effects of some mutations in the 501Y.V2 variant that emerged from South Africa, using serum samples from a small pool of people who had received either the Moderna or Pfizer/BioNTech vaccine. These samples were exposed to synthetic viruses containing some of that variant’s mutations. The 501Y.V2-like variants were able to evade the antibodies more effectively than other variants were, requiring an eightfold increase in the number of antibodies needed to neutralize it. However, the results come from samples obtained from only 44 people and lacked diversity in age and race, which are two crucial factors in COVID-19 outcomes, Drew Weissman, an infectious disease expert who worked on vaccine development, tells the Associated Press.

“The data do raise the possibility that the protection gained from past infection with COVID-19 may be lower for re-infection with the South African variant,” Liam Smeeth, an epidemiologist at the London School of Hygiene and Tropical Medicine who was not involved in the study, tells Reuters. “The data also suggest that the existing vaccines could be less effective against the South African variant.”

In another study, serum samples from 16 people who had received the Pfizer vaccine were exposed to a virus with 10 mutations found in the spike protein of B.1.1.7, often called the UK variant. The synthesized pseudovirus was easily neutralized by antibodies in the samples, keeping hopes about vaccine efficacy high for this variant.

The third study used serum samples from 20 people who had received either the Moderna or Pfizer/BioNTech vaccine to explore how vaccine-induced immunity stood up to specific mutations that affect the spike protein. Although antibodies against SARS-CoV-2 wane as time goes on following infection, B cells retain the ability to target spike proteins and receptor binding domains which is part of the spike that allows the virus to attach to cells for infection. The efficacy of the serum was diminished against the pseudoviruses carrying the mutations compared with those with the dominant SARS-CoV-2 spike protein, and the samples neutralized the viral threat with a one- to threefold increase in antibodies.

https://www.the-scientist.com/news-opinion/new-sars-cov-2-variant-could-evade-antibodies-68375