Pfizer Vaccine Effective Against COVID-19 Variants, in vitro Studies Find

The antibodies from people who have received the Pfizer BioNTech COVID-19 vaccine effectively neutralize SARS-CoV-2 with a key mutation that is also found in two highly transmissible strains, according to results of in vitro studies published on bioRxiv.

Rapidly spreading variants of SARS-CoV-2 have been reported, initially in the United Kingdom and South Africa. These variants have multiple mutations in their spike or S glycoproteins, which are key targets of virus neutralizing antibodies. Though these two rapidly spreading viruses are different, they share the N501Y mutation, which is located in the receptor binding site of the spike protein and results in the virus’s spike protein binding more tightly to its receptor. It has been shown to infect mice more efficiently.

To determine if sera of people who had received the Pfizer-BioNTech COVID-19 vaccine could neutralize SARS-CoV-2 with the N501Y mutation, a virus with this substitution was generated in UTMB’s laboratory. The sera of 20 participants from the previously reported Phase 3 trial neutralized the virus with the mutation as well as they neutralized virus without the mutation. While the virus tested in this experiment did not include the full set of spike mutations found on the rapidly spreading strains in the U.K. or South Africa, neutralization of virus with the N501Y mutation by the PfizerBioNTech vaccine-elicited human sera is consistent with preserved neutralization of a panel of 15 pseudoviruses bearing spikes with other mutations found in circulating SARS-CoV-2 strains. This indicates that the key N501Y mutation, which is found in the emerging U.K and South Africa variants, does not
create resistance to the Pfizer-BioNTech vaccine induced immune responses.

Pfizer, BioNTech, and UTMB are encouraged by these early, in vitro study findings. Further data are needed to monitor the Pfizer-BioNTech COVID-19 vaccine’s effectiveness in preventing COVID-19 caused by new virus variants. If the virus mutates such that an update to the vaccine is required to continue to confer protection against COVID-19, we believe that the flexibility of BioNTech’s proprietary mRNA vaccine platform is well suited to enable an adjustment to the vaccine.