A closely monitored coronavirus vaccine being developed by scientists at Oxford University appears protective in a small study of six monkeys, promising findings that led to the start of human trials late last month, US and British researchers reported Thursday.
The preliminary findings, which have not been rigorously reviewed by other scientists, appeared on the preprint server bioRxiv on Thursday.
British drug manufacturer AstraZeneca announced last month that it was collaborating with researchers from the Oxford Vaccine Group and the Jenner Institute, who are developing the vaccine.
According to the report, some monkeys given a single injection of the vaccine developed antibodies to the virus within 14 days and all protective antibodies developed within 28 days, before being exposed to high doses of the virus.
After exposure, the vaccine seemed to prevent damage to the lungs and prevent the virus from making copies of itself there, but the virus still actively replicated in the nose.
Stephen Evans, professor of pharmacoepidemiology at the London School of Hygiene & Tropical Medicine, said the monkey data was “very sure” good news.
“It is one of the hurdles to be overcome by the Oxford vaccine and it has solved it well,” he said in an emailed comment.
While success in monkeys is seen as an important step, many vaccines that protect monkeys in the lab ultimately fail to protect humans.
Evans said an important finding was particularly comforting: that there was no evidence of an immune-boosted disease, where instead of protection against a virus, a vaccine actually worsens the disease.
“This was a clear theoretical concern for a vaccine against SARS-CoV-2 and finding no evidence for this in this study is very encouraging,” he said.
Last month, British researchers started administering the vaccine to human volunteers in a small safety study, making it one of the few to reach that milestone. 1,000 people received the vaccine on May 13, the researchers said.
Other vaccines in human trials include those from Moderna Inc, Pfizer Inc and BioNTech SE and CanSino Biologics Inc. in China.
Worldwide, more than 100 experimental vaccines are under development to fight the new coronavirus that has so far infected 4.39 million people and killed 296,847.
A vaccine that protects people against the coronavirus can end the pandemic, but finding a vaccine that works and produces enough doses is a huge challenge.
It can normally take up to 10 years to develop a working vaccine, but the urgency of the pandemic has led to faster schedules, and some officials estimate that a working vaccine may be available for emergencies as early as the fall.