A new preprint study has shown that the Pfizer-BioNTech coronavaccine is effective against recent SARS-CoV-2 variants like the Delta plus, Delta-∆144, Lambda and B.1.1.519 variants.¹

Researchers from the US and Germany collaborated to investigate the impact of antigenic variation in the spike protein on the neutralization of the new variants by the Pfizer-BioNTech (BNT162b2) vaccine. Twenty sera samples were collected from the participants 2 or 4 weeks after they had received the second dose of the vaccine. Chimeric SARS-CoV-2 viruses carrying the spike proteins from the recently emerged variants under study and also wildtype viral strain (USA-WA1/2020 SARS-CoV-2) isolated in January 2020, were produced. The chimeric variants as well as the wild type virus were tested for neutralization in all the 20 serum samples.

Results showed that all the study samples were able to neutralize the variant viruses with titers of ≥80. The geometric mean neutralization titers against the wildtype, delta-AY.1, delta-AY.2, delta-∆144, lambda, and B.1.1.519 viruses were found to be 520, 355, 394, 453, 597 and 640, respectively indicating that the neutralization titers against the delta plus were a little lower compared to the wild type virus. But, the neutralization of the lambda and B.1.1.519 variants showed no reduction. 

Delta-AY.1 (first detected in India), delta-AY.2 (first detected in the US) and delta-∆144 (first detected in Vietnam) are sublineages of the delta plus variant (B.1.617.2.1 or AY.1) formed due to a new mutation K417N in the Delta variant. The Lambda C.37) variant was first detected in Peru and the B.1.1.519 was the dominant strain in Mexico.

According to the study authors, since all the variants were susceptible to neutralization by the vaccine induced antibodies, this suggests that antigenic change may not be the reason for the immune escape and consequently increased transmissibility and pathogenicity. They also speculate that more efficient furin cleavage by the variant and not immune escape may be the reason for the breakthrough delta variant infections in vaccinated persons.

However, this study emphasizes that vaccines do work against recently identified variants. Similar to the flu vaccine, modifications to the vaccine may be required in order to accommodate any new variants that may emerge in the future. 

India set a new record by administering 2.5 crore Covid-19 vaccine doses on Friday under the Health Ministry’s Vaccine Seva campaign. Nearly 80 crore population has now been vaccinated.

Vaccination must be aggressively pursued across the country. But only vaccination is not enough to contain the presently circulating variants and minimize the emergence of new variants. Vaccination has to be complemented by Covid-appropriate behavior – masking, frequent handwashing, avoiding crowds and other public health measures if we hope to be Covid-free. 

As the CDC says, “Variants are expected. The best way to slow the emergence of new variants is to reduce the spread of infection by taking measures to protect yourself including getting a COVID-19 vaccine when available.”

Reference

• Liu J, et al. BNT162b2-elicited neutralization of delta plus, lambda, and other variants. bioRxiv posted September 14, 2021, doi: https://doi.org/10.1101/2021.09.13.460163.