COVID-19: Pfizer shot seems to drive back UK variant
A new analysis reveals that the blood of people who received two dosages of the Pfizer-BioNTech vaccine contains large levels of antibodies that can neutralize one of the new, more contagious variants of SARS-CoV-2.
Scientists first detected a new, even more contagious variant of SARS-CoV-2, which is the virus that triggers COVID-19, in the United Kingdom in September 2020.
By early December 2020, U.K. scientists possessed become concerned that it might spread faster and considerably more proficiently than other strains. They also worried about whether available COVID-19 vaccines would offer protection from this new variant.
Researchers in a number of other countries experience since detected the U.K. variant.
Now, nevertheless, a newly published found in the journal Science supplies reassurance that the Pfizer-BioNTech vaccine stimulates the disease fighting capability to produce sufficient quantities of antibodies that may neutralize the new variant.
Pfizer and BioNTech scientists, along with researchers from the University Medical Center of the Johannes Gutenberg-University Mainz found in Germany, completed this study.
Mutations in spike proteins
The scientists report that the U.K. variant, which is formally referred to as B.1.1.7, contains a great unusually large numbers of mutations. These result in 10 adjustments in the sequence of proteins 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 get entry to human being 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 extra 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 dosages 21 days apart during clinical trials.
Of the participants, 14 were aged 57-73 years, and 26 were aged 23-55 years.
The researchers measured the power of the participants’ bloodstream to neutralize “pseudoviruses” bearing either spikes from the U.K. variant or spikes from a mature strain that originated early in the pandemic in Wuhan, China.
Pseudoviruses are made from the outer shell of a dangerous virus, such as for example SARS-CoV-2, and the genetic material of another, harmless virus. The resulting viral particles can invade host cells but are not capable of replicating and spreading.
Antibodies that prevent viruses from entering cells are referred to as “neutralizing” antibodies because they are able to stop an infection in its tracks.
In this analysis, the ability of serum from younger participants to neutralize pseudoviruses bearing the mutant spikes was slightly reduced, whereas the neutralizing ability of serum from older participants had not been significantly altered.
Cautiously optimistic
The study authors write that, based on their experience with influenza vaccines, the observed reduction in neutralizing antibodies isn't “biologically significant.”
They conclude that the U.K. variant is usually, therefore, unlikely to escape the immune protection that the Pfizer-BioNTech vaccine affords.
One limitation of their analysis is that it used pseudoviruses instead of SARS-CoV-2 itself. However, earlier research with SARS-CoV-2 does suggest that pseudoviruses give a trustworthy proxy for immunity to the complete virus.
Nonetheless, the study authors explain that even more experiments with the live virus will be essential to confirm their benefits.Booster vaccine
According to unpublished research, the Moderna vaccine likewise appears to protect against the U.K. strain.
Erring on the side of caution, even so, Moderna are already tests a booster vaccine that targets the proteins of the B.1.351 variant, which scientists first discovered in South Africa.
Both Moderna and Pfizer vaccines are based on mRNA molecules, which offer human cells with the genetic blueprint to create spike proteins.
By themselves, these spikes are harmless, however they provoke an immune response that protects against future contamination by the virus.
One major good thing about mRNA vaccines is that scientists can very quickly create brand-new permutations that protect against emerging strains.
The authors of the Pfizer-BioNTech study conclude:
“Although sustained neutralization of the current B.1.1.7 variant is reassuring, preparation for potential COVID-19 vaccine strain transformation is prudent. Adaptation of the vaccine to a fresh virus strain would be facilitated by the overall flexibility of mRNA-established vaccine technology.”
On an additional optimistic note, they write that their vaccine may also provide security against COVID-19 through other branches of the disease fighting capability, such as for example by boosting degrees of cytotoxic T cells.
So, even if the amounts of antibodies with the capacity of neutralizing an emerging strain will be substantially reduced, the vaccine may well still be effective.
Source: www.medicalnewstoday.com
