Pfizer and BioNTech Announce In Vitro Study Results Showing BNT162b2 Vaccine-Elicited Sera Neutralize SARS-CoV-2 Variant B.1.1.7

Today, Pfizer and BioNTech jointly announced that results from an in vitro study provided additional data showing that sera from individuals vaccinated with the BNT162b2 COVID-19 vaccine retained neutralizing activity against the SARS-CoV-2 B.1.1.7 variant. These findings were posted on the preprint server bioRxiv and submitted to a peer-reviewed journal.

B.1.1.7 is a rapidly spreading mutant strain of the novel coronavirus, first detected in the United Kingdom. It carries a higher number of genetic mutations than usual, with 10 mutations located in the spike protein. Previously published in vitro study data from BioNTech and Pfizer indicated that sera from individuals vaccinated with BNT162b2 maintained effective neutralizing activity against N501Y, a key mutation of concern.

However, in addition to the N501Y mutation, the B.1.1.7 variant carries other genetic mutations. Therefore, in this study, scientists expressed the full-length spike protein of the B.1.1.7 variant on the surface of vesicular stomatitis virus (VSV) and used it to assess the neutralizing potency of sera from individuals vaccinated with BNT162b2.

Serum samples were obtained from 16 volunteers participating in the Phase 1/2 clinical trial of BNT162b2. Eight of these volunteers were aged 18–55 years, and eight were aged 56–85 years. The serum samples were collected on day 21 after administration of the second vaccine dose. Researchers compared the neutralizing capacity of these sera against pseudoviruses expressing two different spike proteins: one expressing the spike protein of the B.1.1.7 variant and the other expressing the spike protein of the reference strain without mutations.

The study results showed that there was no biologically significant difference in the neutralizing capacity of these sera against pseudoviruses expressing the B.1.1.7 spike protein compared to pseudoviruses expressing the non-mutated spike protein ("no biologically significant difference").

The researchers pointed out in the paper that the immune serum of BNT162b2 still has neutralizing ability against pseudoviruses carrying the B.1.1.7 spike protein, meaning that the possibility of B.1.1.7 evading the protective ability mediated by BNT162b2 is very small. Currently, the relationship between the decrease in neutralizing antibody titers and protection against COVID-19 has not been determined. Since COVID-19 vaccines simultaneously stimulate antibody responses and T-cell responses against multiple epitopes of the coronavirus, even if the neutralizing ability of the immune serum decreases, the vaccine may still maintain its protective efficacy.

However, researchers also pointed out that while the sustained neutralizing efficacy of serum is encouraging, they still need to continuously monitor SARS-CoV-2 variants and track their impact on the protective efficacy of COVID-19 vaccines. Preparing for vaccine updates “in advance” is a prudent choice. BioNTech’s mRNA vaccine platform allows for vaccine updates by modifying the mRNA sequence encoding the vaccine. Pfizer and BioNTech believe that the flexibility of this technological platform enables them to rapidly update the vaccine in response to viral variants.

Note: This article is intended to introduce medical and health research and does not constitute a recommendation for treatment plans. For guidance on treatment options, please consult a licensed healthcare provider at a reputable hospital.

References:

[1] Pfizer and BioNTech Publish Results of Study Showing COVID-19 Vaccine Elicits Antibodies that Neutralize Pseudovirus Bearing the SARS-CoV-2 U.K. Strain Spike Protein in Cell Culture. Retrieved January 20, 2021, from https://investors.biontech.de/news-releases/news-release-details/pfizer-and-biontech-publish-results-study-showing-covid-19

[2] Muik et al., (2021). Neutralization of SARS-CoV-2 lineage B.1.1.7 pseudovirus by BNT162b2 vaccine-elicited human sera. bioRxiv, doi: https://doi.org/10.1101/2021.01.18.426984

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