Oxford vaccine showing promising results in early trials.
LONDON — An Oxford University group and BritishSwedish pharmaceutical company AstraZeneca reported Monday that their coronavirus vaccine candidate, on which the U.S. and European governments have placed substantial bets, was shown in early-stage human trials to be safe and to stimulate an immune response.
The study, published in the British medical journal the Lancet and involving 1,077 volunteers, was described as promising. A second report in the same medical journal on a Chinese vaccine showed what researchers not involved in the study described as modest, positive results.
The two vaccines are among 23 candidates being tested in human trials, according to a running tally kept by the World Health Organization. More than 130 others are in preclinical trials. None has yet proved itself to protect people from infection or illness. Scientists caution that no one yet knows what level of immune response will be protective against the virus in the real world through a cross section of humanity — young to old, healthy to those with pre-existing conditions.
But with hopes soaring that a number of vaccines will soon emerge to quiet the global pandemic, governments are making massive investments and pharmaceutical companies are readying production.
The U.S. government has pledged up to $1.2 billion toward the Oxford effort and secured a promise of 300 million doses by October. A European alliance has claimed an additional 400 million doses, while the British government has dibs on 100 million doses, alongside another possible candidate being developed by Imperial College London.
China approved the use of its vaccine within its military in late June.
British Prime Minister Boris Johnson was enthusiastic about the Oxford early-stage results.
“This is very positive news. A huge well done to our brilliant, world-leading scientists and researchers,” Johnson tweeted Monday. “There are no guarantees, we’re not there yet & further trials will be necessary — but this is an important step in the right direction.”
The record-breaking pace of vaccine developers has heartened many who want to see the virus tamed in the new year and life return to normal.
But much about the virus remains unknown. Just last week, British researchers reported that people infected with the virus may see defensive antibodies against it quickly fade, within months, raising the possibility that long-term protection may be elusive.
Still, researchers at Oxford and elsewhere are optimistic that they can stimulate a permanent praetorian guard against infection.
“We hope this means the immune system will remember the virus, so that our vaccine will protect people for an extended period,” Andrew Pollard, one of the leaders of the Oxford study, said in a statement. “However, we need more research before we can confirm the vaccine effectively protects against SARS-CoV-2 infection, and for how long any protection lasts.”
Large-scale, real-world trials of the Oxford vaccine are underway in Britain, Brazil and South Africa. The U.S. plans to test it later this summer, along with a handful of other candidates, in clinical trials with about 30,000 volunteers each.
The Oxford vaccine is named ChAdOx1 nCoV-19 and was made from a weakened and nonreplicating version of a common cold virus, an adenovirus. The vaccine has been engineered to express a bit of the coronavirus that produces the spike protein that the virus uses to enter and infect human cells.
Paul Offit, director of the Vaccine Education Center at Children’s Hospital of Philadelphia, said it’s unclear how protective the immune memory in T cells will be against the coronavirus, in part because immune memory is typically more valuable against pathogens that have a longer incubation period than the coronavirus.
His biggest concern about the Oxford study is that while the vaccine triggered the immune system best when given with a second shot, that twodose regimen was tested in only 10 patients.
“I’d want to see in a phase two trial: two doses consistently inducing a neutralizing antibody response — and that it’s relatively long lived, not months, not a few weeks,” Offit said.
Infectious disease experts caution that vaccines must be widely administered to protect the general population, and in an era of widespread skepticism, and even overt hostility toward research and scientists, any vaccine that underperforms or causes serious side effects will set back the effort.
An editorial in the Lancet warned, “The race for a vaccine moves fast, as the need for a solution is evident, but we cannot forget that safety is of the highest importance.”
In a reflection of how eagerly awaited even very early vaccine results have become during the pandemic, results from the Oxford trial were leaked to news outlets in the days before publication, and the hype continued to build over the weekend.
“To me, the message is: It looks like it warrants further study. There’s no showstopper here,” said Dr. Peter Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine. “The bottom line is, there’s maybe some promise, but definitely you cannot declare victory by any means on these two vaccines. There’s nothing here that would cause me to say we can now release this to the public.”
“We hope this means the immune system will remember the virus, so that our vaccine will protect people for an extended period.” Andrew Pollard, one of the leaders of the Oxford study