The virus now has more transmissible forms and those that have been shown to evade antibody protection in lab studies and real-world clinical trials.
The research was part of a larger, phase three clinical trial also showing the vaccine was highly effective even after six months.
The companies said the results contained data on more than 12,000 participants who had been fully inoculated for at least six months.
The vaccine, which was the first in the U.S.to receive emergency use authorization from the Food and Drug Administration, is 91% effective against symptomatic disease and was even more effective at preventing severe disease, Pfizer reported. The firms said the data demonstrates the vaccine's high efficacy against this variant.
Experts fear new variants of COVID-19 from South Africa and Brazil may be resistant to existing vaccines and treatment.
The South African variant has been detected in several areas of England.
Although the new study did not look at the Oxford University/AstraZeneca vaccine, Prof Moss said the evidence for the jab is that "it's very, very effective".
US Officer on Trial for Death that Sparked Protests Against Police Brutality
Floyd was "just kind of shaking his head and putting his hands in the air, like, 'Why is this happening to me?'" Martin said. Chauvin is standing trial on three counts: second-degree murder, third-degree murder and second-degree manslaughter.
"In South Africa, where the B.1.351 lineage is prevalent and 800 participants were enrolled, nine cases of Covid-19 were observed, all in the placebo group", the companies said.
With rising cases and several states even lifting mask mandates and with more infectious variants also spreading, health authorities are hoping that the contracts it struck with the now approved vaccine makers will be enough for its entire population.
"The Pfizer data are a big deal", said Shane Crotty, a virologist at the La Jolla Institute for Immunology in San Diego, noting that the results offer the first data in humans about how so-called mRNA vaccines such as Pfizer's will perform against the South African variant.
"Our findings extend those from smaller studies reported elsewhere and support a potential strategy of providing a single dose of vaccine to persons with a confirmed prior history of coronavirus infection, along with two doses for people not previously infected", said Susan Cheng, Associate professor at the Cedars-Sinai Medical Centre in California, US.
The longevity of the immune response is truly good news.
The vaccine is also 100 percent effective in preventing severe cases as defined by the US Centers for Disease Control - or 95.3 percent effective against severe cases if we are to follow the definition of the US Food and Drug Administration. "The high vaccine efficacy observed through up to six months following a second dose and against the variant prevalent in South Africa provides further confidence in our vaccine's overall effectiveness".