South African Variant Could Reduce Vaccine Protection: Pfizer


On Wednesday, 17 February, Pfizer Inc/BioNTech said that a new study suggests their mRNA vaccine might not be as effective against the South African variant of the coronavirus.

The laboratory study showed that the variant may reduce antibody protection from the vaccine by two-thirds, reported Reuters.

It also found that the vaccine could still neutralise the virus, but to what extent is the question. There is not enough evidence from the trials in people that this variant reduces vaccine protection. Still, Pfizer is reportedly making investments for a booster shot or an updated version of their vaccine.

The study found the vaccine was still able to neutralize the virus and there is not yet evidence from trials in people that the variant reduces vaccine protection, the companies said.

Should we be worried? First, let’s understand the study.


The Study Findings

The study findings were published in the New England Journal of Medicine.

Scientists from Pfizer Inc/BioNTech and the University of Texas Medical Branch first developed an engineered virus that contained the same mutations carried on the spike portion of South Africa Variant, also known as B.1.351. The virus uses the spike to enter human cells and this spike is the main target of most COVID-19 vaccines.

Then, the researches tested this virus against blood samples of people who had taken the vaccine and found “approximately a two- thirds reduction in the level of neutralizing antibodies” as compared to its effects on the original virus in U.S. trials.

Importantly, a study published in NEJM by Moderna also revelled similar data: a sixfold drop in antibody levels in the South African variant. Still, they maintained that their vaccine’s actual efficacy against the variant is still not determined and their vaccine would potentially still work.

Should We Be Worried?

Yes and no.

For one, we don’t know what level of antibodies are required to protect us against the virus. In other words, we don’t know yet if a two-thirds reduction will mean the virus is less effective as we don’t have a benchmark for antibody levels.

University of Texas Medical Branch professor and study co-author Pei-Yong Shi told Reuters, “We don’t know what the minimum neutralizing number is. We don’t have that cutoff line,” and added that perhaps the immune response observed will likely be significantly above where it needs to be to provide protection. In other words, the Pzfizer vaccine could still work against this variant.

In clinical trials, both the Pfizer/BioNTech vaccine and a similar shot from Moderna Inc offered some protection (after one dose) and resulted in an antibody response lower than the reduced levels caused by the South African variant in the laboratory study.

Professor Pei-Yong Shi said that it was likely that while the vaccine may have lower effectiveness, it would still protect against severe disease and death.

Virologist Dr Shahid Jameel adds, “Another thing is that all over the world we are seeing mutants are developing. Whatever we know so far say that the vaccines are working on mutants but not as well, which essentially means that even if you get a mutant, you get infected but the severity of the disease will be reduced. This is still a good enough reason to take the vaccine anyway.”

Health experts around the world have said that this would help prevent healthcare systems from becoming overwhelmed.

Still, more research is needed to determine the antibody benchmark level and vaccine effectiveness against new variants and mutations.

On the other hand, as cases slowly rise, we should continue to be vigliant and practice social distancing and hygiene protocols as new variants enter India.

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