There is no evidence that the Pfizer coronavirus vaccine will need to be tweaked to fight off variants, its developers say.
BioNTech wrote in its latest financial reports that the jab could block infections from variants in most cases, and almost all hospitalisations and deaths.
But the German firm added it was still monitoring the situation, in case a variant did appear that could get around protection from its shot.
Experts said today Britain was in a 'very good position' against variants, with more than two thirds of adults - 35million people - having received at least one dose.
Concerns have been raised over one of the Indian variants (B.1.617.2) which was designated a 'variant of concern' last week.
But scientists said there is still no evidence that it can get around jab-sparked immunity.
It comes after official data revealed almost half of all cases in London are now down to the Indian variants.
BioNTech said in their latest financial reports that the jab would block infections from variants in most cases, and almost all hospitalisations and deaths
Professor Christina Pagel, a mathematician at University College London and member of Independent SAGE, produced this graph using PHE data to show that the proportion of Covid cases being caused by the Indian variant type .2 has surged to almost 40 per cent
Public Health England figures reported on May 5, taken from tests up to around April 27, show that fewer than half of cases have been in international travellers in most areas
UP TO HALF OF LONDON COVID CASES ARE INDIAN STRAIN
Up to half of all Covid cases in London could be caused by the new Indian variant, according to official figures.
It was last week designated a 'variant of concern' by Public Health England because scientists say it can spread as fast – or even faster – than the dominant Kent strain (B.1.1.7).
But there is no evidence it will cause worse disease or make vaccines less effective, experts say, though it must be monitored in case it turns out to be more dangerous.
In a report last week PHE said it 'may have replaced B.1.1.7 to some extent'. Testing figures suggest that only 50.2 per cent of all positive cases in London were caused by the Kent variant in late April, down from over 90 per cent in March.
The other 49.8 per cent were caused by other strains of the virus. The most common one was the Indian variant (B.1.617). Data showed it made up at least 37.5 per cent of confirmed cases but the exact proportion is unknown because not all samples have been thoroughly analysed.
Professor Christina Pagel, a mathematician at University College London and member of Independent SAGE, said the other half was 'potentially all' the Indian variant. Despite the rapid spread, cases in London remain stable.
BioNTech said in its latest financial report: 'To date, there is no evidence that an adaptation of BioNTech's current Covid vaccine against key identified emerging variants is necessary.'
It added there was a 'comprehensive strategy to address these variants should the need arise in the future'.
Scientists are spooked by variants because they carry key mutations that change the shape of their spike protein, which antibodies bind to to stop infections.
But experts stress this theory excludes other parts of the immune system - such as T-cells - which also have a key role in fighting off viruses.
Studies in Israel and Qatar where most residents have been jabbed found Pfizer's shot was up to 75 per cent effective at blocking infections with the South African variant (B.1.351), and also warded off most cases with the Kent variant (B.1.1.7).
It was more than 97 per cent effective at blocking hospitalisations and deaths in infections with either variant.
This is a slight drop from the 95 per cent figure from trials, but still far above levels for many jabs such as the flu shot which is often less than 50 per cent effective.
Numerous studies have also suggested Pfizer's jab protects against the Brazilian strain (P.1).
There is currently no evidence that the Belgian-made jab is less effective against either of the three Indian variants.
Professor Ravi Gupta, a clinical microbiologist at Cambridge University, says early laboratory analysis suggests vaccines will still protect against severe disease from these strains.
Cases of Indian variants, particularly B.1.617.2, have been rising since it was first identified in the UK last month.
They accounted for more than 30 per cent of Covid cases on May 9, according to variant tracker GISAID, up from five per cent a week ago.
But this is in the context of cases continuing to fall across the country.
The director of the UK's variant sequencing programme Professor Sharon Peacock said today the country was in a 'very good position' against variants.
'I think that, for me, looking at the overall landscape, I’m still very delighted that vaccines are working, that, you know, whatever is out there, vaccines are working, and disease rates are falling, so we’re in a very good position,' she said.
'As scientists we just have to keep our eye on this so that we just maintain that trajectory.'
She added simple moves such as washing hands and social distancing were still the best defences against the virus and variants.
'I think the point is to note is that this isn’t a special variant of concern that’s going to get around washing your hands and distancing and wearing a mask, and being in a well-ventilated place – I think that’s the key thing.
'So, for me, the message is we just keep doing those things but we’re in a better position now because we have falling rates, and a good vaccination programme, which I would anticipate will just continue to increasingly protect our population.'
The Pfizer vaccine was 100 per cent effective at stopping hospitalisation or death from Covid during trials, and 95 per cent effective at blocking infections.
It is based on mRNA technology, which uses the body to produce harmless Covid spike proteins.
These trigger an immune reaction against the virus, ensuring the body has defences should the real virus come along.