The head of Britain's vaccination deployment effort says the world faces around 4,000 variants of the virus that causes COVID-19.
As a result of new mutated versions, vaccine manufacturers are looking for ways to improve the shots to resist the virus variants, Vaccine Deployment Minister Nadhim Zahawi said Thursday.
British researchers plan to test a mix of two vaccines - the Pfizer-BioNTech and Oxford-AstraZeneca injections - to see if the two together can create stronger immunity.
Experts say thousands of individual changes arise as the virus mutates and develops into new variants over time. However, only a small number of mutations are likely to change the virus in an important way, the British Medical Journal reports.
So far, the most concerning versions identified by scientists are the so-called British, South African and Brazilian variants, which appear to spread more quickly than others.
Zahawi said it was likely that the vaccines available now will be effective against the new virus variants.
"It's very unlikely that the current vaccine won't be effective on the variants...especially when it comes to severe illness and hospitalization," Zahawi told Britain's Sky News.
He said major vaccine manufacturers are working on ways "to make sure that we are ready for any variant," adding that "there are about 4,000 variants around the world of COVID now."
"We are keeping a library of all the variants so that we are ready to respond...to any challenge that the virus may present and produce the next vaccine," Zahawi said.
The coronavirus has killed 2.2 million people worldwide since it was found in late 2019, Johns Hopkins University of Medicine reports.
Israel leads the world in effectively vaccinating its citizens. It is followed by the United Arab Emirates, the United Kingdom, Bahrain, the United States and then Spain, Italy and Germany.
Britain has begun a trial to consider the immune response that comes from using the vaccines from both Pfizer and AstraZeneca in two injections. Results of the trial are expected in June.
The trial will combine an mRNA injection -- such as the one developed by Pfizer and BioNtech -- and an adenovirus viral vector vaccine developed by Oxford University and AstraZeneca. Viral vector vaccines carry genes that prepare the body to fight against COVID-19.
Russia's Sputnik V is also a viral vector vaccine. In a separate trial, it is being tested in combination with AstraZeneca's vaccine.
The British researchers said there are two main advantages to vaccinating people with two different vaccine versions: it may increase immune responses and it would give governments more ways to get the vaccines out to their populations.
Matthew Snape is an Oxford vaccine expert who is leading the trial. He told reporters that using different vaccine injections had proven to be effective in fighting Ebola. He added that scientists believe the new combinations will create a "good immune response."
I'm Susan Shand.