The UK’s vaccines minister has told the public to have confidence in the Oxford/AstraZeneca vaccine amid concerns over its effectiveness against the South African coronavirus variant.

South Africa has suspended the rollout of the British-designed vaccine to healthcare staff following results of an early trial, which found it was not effective at preventing mild illness caused by the more infectious mutation.

But AstraZeneca said it believed the vaccine would still protect against severe disease from the variant.

Nadhim Zahawi urged people to keep faith with the Oxford jab, as scientists working on the vaccine raised the prospect of having a booster dose available by the autumn.

Writing in the Daily Telegraph, Zahawi said: “While it is right and necessary to prepare for the deployment of an updated vaccine, we can take confidence from the current roll out and the protection it will provide all of us against this terrible disease.

“We need to be aware that even where a vaccine has reduced efficacy in preventing infection there may still be good efficacy against severe disease, hospitalisation, and death. This is vitally important for protecting the healthcare system.”

On Monday morning, health minister Edward Argar said there have been 147 confirmed cases of the South African coronavirus variant in the UK but acknowledged his figures may be “a day or so out”.

“So it’s still very much not the dominant strain here, the dominant strain here is very much the historic one, the one we’ve been dealing with since last year, and to a large degree the so-called Kent variant.”

Scientists have agreed more research is required into the level of protection the Oxford vaccine affords against the South African variant, but some expressed concern over the preliminary findings from the southern hemisphere.

AstraZeneca said on Sunday the fact the study into the E484K mutation involved 2,000 people who were mostly young and healthy meant it had “not been able to properly ascertain” whether it prevented against severe illness and hospital admission.

But the Anglo-Swedish pharmaceutical giant said it believed “our vaccine will still protect against severe disease” as the neutralising antibody activity is “equivalent to other Covid-19 vaccines that have demonstrated activity against more severe disease”.

Professor Sarah Gilbert, the Oxford vaccine’s lead researcher, said her team was working on having an adapted version of their jab that could tackle the South Africa mutation – of which cases have been found in England – “available for the autumn”.

She said: “This year we expect to show that the new version of the vaccine will generate antibodies that recognise the new variant. Then it will be very much like working on flu vaccines. It looks very much like it will be available for the autumn.”

Zahawi said he and professor Jonathan Van-Tam, England’s deputy chief medical officer, agreed there was likely to be a follow-up jab programme later in the year.

“We see very much probably an annual or booster in the autumn and then an annual (jab), in the way we do with flu vaccinations where you look at what variant of virus is spreading around the world, rapidly produce a variant of vaccine and then begin to vaccinate and protect the nation,” he told BBC One’s Andrew Marr Show.

The government’s announcement that it had secured 20 million more rapid-result coronavirus tests signalled that the prime minister – due to set out his road map for easing restrictions later this month – could be preparing to relax lockdown rules in some settings as daily Covid deaths fell to their lowest level in weeks.

Figures showed that a further 373 people had died within 28 days of testing positive for Covid-19 as of Sunday, bringing the UK total to 112,465.

The lateral flow antigen tests, which can return results in under 30 minutes, are the first British-made tests to be validated by Public Health England in the laboratory and will be deployed to test NHS and care home staff, as well as in schools, universities, and for key workers.

But Tim Spector, professor of genetic epidemiology at King’s College London, said the impact of Covid was likely to be felt at large gatherings long after lockdown was over.

He told Times Radio: “I can’t see us suddenly having another Cheltenham Festival with no regulations again, I can’t see us having massive weddings with people coming from all over the world.

“I think for the next few years those days are gone.”