Pfizer vaccine shows signs of efficacy against new coronavirus variants in laboratory study
A study has provided hope the approved Pfizer-BioNTech vaccine may be effective against the two most concerning new coronavirus variants.
With an effective jab long being hailed as a route out of the pandemic, concerns were raised the mutated virus would not respond to the Pfizer-BioNTech and University of Oxford-AstraZeneca vaccines being rolled out across the UK.
Experts are largely optimistic the vaccines will work against the so-called UK variant, which is thought to have emerged in Kent in September. An additional mutation in a key site of the “South African” variant, however, has left some sceptical.
With officials and scientists alike stressing research is required before hard conclusions can be drawn, a team from the University of Texas Medical Branch in Galveston engineered coronaviruses with a mutation shared by the two variants under laboratory conditions.
These laboratory-based coronaviruses were then exposed to the blood of 20 people who received the second dose of the Pfizer-BioNTech vaccine two to four weeks earlier.
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Results revealed a similar number of immune-fighting antibodies were produced against the variant as they were for the “original virus”.
The research has led to mixed responses from experts, with one hailing it “very encouraging news”.
With the engineered coronavirus lacking some of the mutations in the troublesome variants, however, another claimed the results are “misleading” and “should be ignored”.
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The preliminary results are yet to be published in a peer-reviewed journal, but appear on the pre-print website bioRxiv.
Viral mutations are entirely expected, with the majority having a neutral effect.
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Concerns were raised, however, when it emerged both the UK and South African variants share a mutation called N501Y.
This affects the virus’ so-called spike protein, which it uses to enter cells. Officials and scientists are confident this mutation aids transmission, triggering the recent surge in UK coronavirus cases.
The spike protein is also a target for many vaccines, leaving many worried what the mutation may mean for jab efficacy.
To learn more, the Texas scientists generated the N501Y variant in the laboratory.
It was then exposed to the vaccinated participants’ blood to uncover if the same neutralising antibodies, which defend a cell against infection, were produced as they are for a more established variant of the virus.
The results suggest there was “no reduction in neutralisation activity against the virus” bearing the mutation.
Only the Pfizer-BioNTech vaccine was studied, with the pharmaceutical giant’s chief scientific officer being involved in the trial.
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“This is indeed an important finding to calm any concerns about lack of vaccine coverage for the variants,” said Professor Daniel Altmann from Imperial College London.
“The protective, neutralising antibody response that blocks spike entry is ‘multi-epitope’ – that is, targeted to several bits – so it was unlikely protection would be significantly impaired.
“Neutralisation of the variant looks excellent from this study.”
Not everyone is as optimistic, however.
“The short report, showing a single spike mutation has little impact against serum from individuals vaccinated with the Pfizer vaccine, is misleading for a number of reasons,” said Professor Ravi Gupta from the University of Cambridge.
“The mutation selected is only one of eight in the UK variant and in fact was not expected to have significant impact alone.
“The number of times the experiments were repeated is not given.
“This work should be ignored until properly conducted work is made available. The present paper would not pass peer review in its current form.”
Professor Stephen Evans from the London School of Hygiene & Tropical Medicine, however, stressed “the lack of peer review is not a major limitation”.
“This is good news, mainly because it is not bad news,” he added.
“Had the opposite result been found, that the vaccine did not seem to have efficacy against the variation of the virus studied, that would have been bad and very concerning.
“So, yes this is good news, but it does not yet give us total confidence the Pfizer (or other) vaccines will definitely give protection.
“We need to test this in clinical experience and the data on this should be available in the UK within the next few weeks.
“This lab-based testing is useful, but is not the exact variant found in the UK.”
Many experts agreed further research is required, with the results of an official Public Health England investigation expected soon.
Unlike the UK variant, the South African variant carries a mutation called E484K – also on the spike protein – which was not studied in the Texas research.
“The South African variant has accumulated two additional changes in the key receptor-binding domain of the spike gene,” said Professor Lawrence Young from the University of Warwick.
“These changes are very likely to influence the infectiousness of this South African variant and may also impact its ability to be blocked by antibodies, particularly the monoclonal antibodies that have already been used as a therapy.”
Nevertheless, Professor Young called the results “very encouraging news”.
“The pre-print demonstrates antibodies from individuals vaccinated with the Pfizer/BioNTech vaccine is able to block infection (neutralise) with an engineered form of the virus that contains one of the key mutations in the spike gene (N501Y) found in the UK variant,” he added.
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