Scientists first detected a new, more contagious variant of SARS-CoV-2, which is the virus that causes COVID-19, in the United Kingdom in September 2020.
By early December 2020, U.K. scientists had become concerned that it could spread faster and more efficiently than other strains. They also worried about whether or not currently available COVID-19 vaccines would provide protection against this new variant.
Researchers in several other countries have since detected the U.K. variant.
Now, however, a newly published in the journal Science provides reassurance that the Pfizer-BioNTech vaccine stimulates the immune system to produce sufficient quantities of antibodies that can neutralize the new variant.
Pfizer and BioNTech scientists, along with researchers from the University Medical Center of the Johannes Gutenberg-University Mainz in Germany, carried out this study.
The scientists report that the U.K. variant, which is formally known as B.1.1.7, contains an unusually large number of mutations. These result in 10 changes in the sequence of amino acids that comprise the virus’s spike proteins.
The spikes, which give all coronaviruses their characteristic crown-like appearance, are a critical target for the immune system because they allow SARS-CoV-2 to gain entry to human cells.
Of particular concern, one of the mutations is in the “receptor binding domain,” which is the part of the spike that binds to receptors in the membrane of host cells. Spikes with this particular mutation bind more tightly to these receptors.
To investigate whether or not these 10 mutations in the spike compromise the efficacy of their vaccine, the researchers ran tests on blood from 40 volunteers who had received the recommended two doses 21 days apart during clinical trials.
Of these participants, 14 were aged 57–73 years, and 26 were aged 23–55 years.
The researchers measured the ability of the participants’ blood to neutralize “pseudoviruses” bearing either spikes from the U.K. variant or spikes from an older strain that originated early in the pandemic in Wuhan, China.
Pseudoviruses are made from the outer shell of a dangerous virus, such as SARS-CoV-2, and the genetic material of another, harmless virus. The resulting viral particles can invade host cells but are incapable of replicating and spreading.
Antibodies that prevent viruses from entering cells are known as “neutralizing” antibodies because they can stop an infection in its tracks.
