After establishing last week that the vaccine was capable of neutralising the concerning N501Y mutation in the variant, further analysis of blood taken from trial participants now suggests the Pfizer jab can overcome a number of genetic changes present within the virus.
The latest study, which has not yet been peer reviewed, was conducted on a synthetic virus with 10 mutations that are characteristic of the spike protein seen in the UK variant, known as B.1.1.7.
Blood samples drawn from 16 vaccinated participants in prior clinical trials were exposed to the so-called ‘pseudo-virus’, which was effectively neutralised as a result.
This suggests that antibodies present in the blood - produced in response to the Pfizer vaccine - are capable of tackling both B.1.1.7 and the previous form of Sars-CoV-2 that the jab was initially designed for.
The researchers said their results indicate it is "unlikely that the B.1.1.7 lineage will escape BNT162b2-mediated (Pfizer/BionTech vaccine) protection".
The findings provide further hope that the newly emerging coronavirus variants won’t render the current generation of vaccines redundant, which are seen as vital to ending the acute phase of the pandemic.
It also suggests that manufacturers may not need to tweak their vaccine candidates. This would also require the mass production of new doses, which would then need to be distributed across the world - a process that could take months.
However, more analysis of the effectiveness of the Covid-19 vaccines against B.1.1.7 and the other coronavirus variants is needed before any firm conclusions can be drawn.
BioNTech has said it plans to publish a more detailed analysis of the likely effect of its vaccine on the South African variant within a few days.
The variants are said to be more transmissible than previously dominant ones, but they are not thought to cause more serious illness.
AstraZeneca, Moderna and CureVac are also testing whether their respective shots will protect against the fast-spreading variants. They have not released the results of those tests.
Last week, Pfizer said a laboratory study showed that its vaccine was effective against N501Y, found in both of the highly transmissible variants spreading in Britain and South Africa.
Pfizer said it had tested a total 16 different mutations present in the variants and none had any significant impact on how its vaccine worked.
Danny Altmann, a professor of immunology at Imperial College London, said: “I find it impossible to remember a time in immunology when so many scientists around the world have raced to answer a single question, and one with of such overwhelming global significance.”
He added that most cases in the latest Pfizer study “show a slight reduction in neutralisation against the mutant, hopefully not enough to impair protection. But how much reduction would be enough to really narrow our vaccination escape strategy?”
Dr Jonathan Stoye, a virologist at the Francis Crick Institute, said the findings “should not be considered surprising” but are “very welcome”.
Separate research from a team of Israeli scientists has meanwhile indicated that a single dose of the Pfizer/BioNTech vaccine may provide less protection than originally hoped.
Professor Nachman Ash, Israel’s coronavirus tsar, said a single dose appeared “less effective than we had thought”, and also lower than Pfizer had suggested.
By contrast, those who had received their second dose of the Pfizer vaccine had a six- to 12-fold increase in antibodies, according to data released by Sheba Medical Center in Tel Hashomer on Monday.
Pfizer says its vaccine is around 52 per cent effective after the first dose, and increases to about 95 per cent a week or so after the second dose.
Addressing the Israeli findings, Sir Patrick Vallance, the UK government’s chief scientific adviser, said studies showed that from day 10 after vaccination to 21 days and beyond, efficacy was "much more like 89 per cent“ - though he admitted "when you get into real-world practice things are seldom quite as good as clinical trials".