The UK government says a COVID-19 booster in the northern autumn and then annual jabs are likely while Iranian researchers have unveiled the country's second coronavirus vaccine as countries race to administer injections in the face of new variants.
The UK has already injected more than 12 million first doses of COVID-19 vaccines and is on track to meet a target to vaccinate everyone in the top most vulnerable groups by mid-February.
Among coronavirus variants currently most concerning for scientists and public health experts are the so-called UK, South African and Brazilian variants, which appear to spread more swiftly than others.
"We see very much probably an annual or a booster in the autumn and then an annual (vaccination), in the way we do with flu vaccinations where you look at what variant of virus is spreading around the world," vaccine deployment minister Nadhim Zahawi told the BBC's Andrew Marr Show.
AstraZeneca said on Saturday its vaccine developed with the University of Oxford appeared to offer only limited protection against mild disease caused by the South African variant of COVID-19, based on early data from a trial.
The UK on Sunday reported a further 15,845 cases and 373 deaths within 28 days of a positive test, according to official figures.
The success of the UK's vaccine rollout, however, is spurring debate about how soon the government can ease broader lockdown restrictions amid plans to reopen schools in England in March.
As some countries consider a vaccine passport to enable the easing of travel measures, Zahawi said the UK would not introduce such a system but people could seek proof from their doctor if needed.
"That's not how we do things in the UK. We do them by consent," he said.
"We yet don't know what the impact of vaccines on transmission is and it would be discriminatory."
Meanwhile, Iranian state TV reported on Sunday that scientists had unveiled the country's second homemade coronavirus vaccine and will begin human trials.
The Razi Cov Pars vaccine manufactured by the Razi Vaccine and Serum Research Institute is both injectable and inhalable.
Ali Eshaqi, the institute's manager, said the vaccine will be tested on 13 people within eight days and then if there are no serious reactions, it will be tested on groups of 20 to 120 persons.
Eshaqi said the vaccine has already been tested on animals including mice, rabbits, hamsters and monkeys.
The country is also working on a joint vaccine with Cuba.
Iran plans to import 17 million doses of vaccine from the international COVAX program and millions more from other countries.
Iran, with a population of more than 83 million, has struggled with the worst outbreak in the Middle East.
Its confirmed virus death toll is 58,469.