COVID-19 Variants with Spike Mutations Pose Hazard to Vaccine Efficacy

According to a recent Singapore study, the antibody neutralization activity of convalescent patients with the coronavirus illness 2019 (COVID-19) appears to be reduced against the B.1.1.7 and B.1.351 strains of SARS-CoV-2 due to changes in the virus's Spike protein.

COVID-19 Variants with Spike Mutations Pose Hazard to Vaccine Efficacy
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"While governments throughout the world are working to get COVID-19 vaccinations to the bulk of the public as quickly as possible," the researchers wrote, "it is of significant worry that all presently licensed vaccines and those continuing in development are based on the ancestral Spike sequence."

"Our findings have emphasized the critical need to produce novel COVID-19 vaccines that are not solely based on the ancestral Spike sequence," they said.

The neutralizing activity of 57 convalescent plasma samples from COVID-19 patients was evaluated against live virus isolates of the wildtype, B.1.1.7, and B.1.351. In comparison to the virus bearing the ancestral Spike protein sequence, the samples demonstrated lower neutralizing activity against both variations. [Vaccines 2021;6:125] [NPJ Vaccines 2021;6:125]

Plaque reduction neutralization test (PRNT) scores for the 50-, 80-, and 90-percent cutoffs all revealed substantial declines. Such decreases were more pronounced against the B.1.351 variety in all cases, implying higher neutralizing activity attenuation.

The results of a neutralization assay against pseudo viruses encoding Spike protein sequences from the wildtype, B.1.1.7, or B.1.351 strains were corroborated by these findings. While most patient samples could still neutralize SARS-CoV-2 at high concentrations, activity against both nonwild type variants was severely reduced.

The severity of the disease proved to be a significant determinant in neutralizing action. Samples from COVID-19 patients with severe disease displayed higher neutralizing potency against SARS-CoV-2 in both the live virus and pseudo virus assays than samples from individuals with moderate or mild sickness.

However, even after stratifying by disease severity, plasma samples had considerably lower neutralizing activity against the B.1.1.7 and B.1.351 strains than the wildtype virus.

“The rapid spread of SARS-CoV-2 viral variants from the United Kingdom and South Africa has raised significant concerns worldwide about the degree of protection provided by humoral immune responses elicited by natural infection or vaccination,” the researchers wrote, adding that some studies have already shown significant reductions in anemia.

The current findings added to the increasing literature on COVID-19 variations by revealing that the humoral immune responses produced by the original outbreak in Singapore are less than those elicited by emerging variants.

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