The preliminary data from South Africa marks a potential setback and bolsters concern that some of the emerging variants of the virus may be able to elude at least some of the new vaccines.
Vaccine developers say they are creating “libraries” of tweaked vaccines that they could quickly test against emerging viral variants. They say that some of the new and improved versions of their vaccines could be tested and released within the year, if necessary.
The variant first identified in South Africa, known as B.1.351, appears to be more transmissible and has subtle but important changes to its telltale spike protein, which the virus uses to attach to and then enter human host cells.
Thousands of new variants are circling the planet, but only a few rise to the level of “variants of concern,” because they are more transmissible, more lethal or suspected of being able to dodge the antibodies produced by vaccination.
The research from South Africa, announced in a news release from Oxford University, did not contain a lot of data, leaving scientists not involved in the study unsure what to conclude and awaiting a detailed preprint or publication in a scientific journal.
According to the news release, the study was conducted by the University of the Witwatersrand and Oxford in South Africa and examined adults between the ages of 18 and 64 from June 24 to Nov. 9 across seven sites. Half of the participants got at least one dose of the Oxford vaccine, and half received at least one dose of a placebo.
The median age of the participants was 31, so the researchers could not produce statistically robust conclusions about whether the vaccine protected against severe covid-19 cases, hospitalizations and deaths, because so few young adults get severe illness, and the number of participants in the study was small.
Still, the Oxford team stressed that their vaccine had “high efficacy against the original coronavirus strain” — but “minimal protection” against mild disease from the variant in South Africa.
The scientists did not provide percentage breakdowns.
In a statement, Andrew Pollard, chief investigator on the Oxford vaccine trial, said the study “confirms that the pandemic coronavirus will find ways to continue to spread in vaccinated populations, as expected.”
Speaking to the BBC, Oxford vaccine developer Sarah Gilbert said the coronavirus vaccines in use worldwide “have a reduction in efficacy against some of the variant viruses.”
“What that is looking like is that we may not be reducing the total number of cases, but there’s still protection in that case against deaths, hospitalizations and severe disease,” she told the “Andrew Marr Show.”
Gilbert added that her team is developing a vaccine to protect against the variant identified in South Africa. “It’s not quite ready to vaccinate people yet. It’s easy to adapt the technology, develop a new vaccine, which will have to go through a small amount of clinical testing, not nearly the same amount as we had to go through last year,” she said.
Public health officials have been relieved in recent days by preliminary reports that the Novavax and Johnson & Johnson vaccines were up to 60 percent effective against the variant from South Africa. That efficacy is good but substantially lower than against the original virus.
That variant contains a worrisome mutation, at a site on the virus RNA called E484K, that has drawn close scrutiny from infectious-disease experts, who have given it the nickname “Eeek.”
The “Eeek” mutation has been seen in variants in Brazil and Britain. It has also been identified in recent days in a handful of cases in the United States.
On Friday, the Oxford-AstraZeneca team reported that its vaccine may help keep people from spreading the virus, offering a hopeful but uncertain answer to one of the great remaining questions of the pandemic.
In a preprint of an article under review at the Lancet medical journal, the Oxford University vaccine developers reported that based on follow-up studies of their clinical trials in Britain, which found the vaccine safe and effective, there is also “the potential for the vaccine to reduce transmission of the virus.” That data is preliminary, and independent researchers are awaiting more information.