Oxford's COVID-19 vaccine fails key animal trial: Details here
The COVID-19 vaccine developed by Oxford University has failed a key animal trial. ChAdOx1 nCoV-19 was tested on monkeys, but the shot could not protect the animals from contracting the novel coronavirus. The result has raised serious questions over the efficacy of the vaccine candidate as well as the pre-emptive efforts going on to mass-produce it. Here are more details.
ChAdOx1 nCoV-19: A front-runner in the race for COVID-19 vaccine
Developed from a weakened version of a common cold virus from chimpanzees, ChAdOx1 nCoV-19 has been hailed as a front-runner in the race for vaccines, thanks to its bold market availability timeline of September-October. It went into human trials late last month and is also being mass-produced pre-emptively by leading drug-makers Serum Institute of India and AstraZeneca.
Trial on rhesus macaque monkeys
While the human trials of the vaccine are still on, results from early tests on rhesus macaque monkeys, carried out by the NIH, are here, and they are not impressive. Specifically, the team has noted that injecting the monkeys with ChAdOx1 does not generate an immune response strong enough to help the animals fight the novel coronavirus and stay protected, The Telegraph reported.
A total of nine monkeys were exposed to coronavirus
In the test, which was conducted in the US, as many as nine monkeys were infected by the coronavirus. Of these, six were given a single dose of ChAdOx1 nCoV-19 and exposed to the coronavirus, while the others were challenged without any vaccination. After that, both the groups were monitored, which revealed that the vaccinated group did not have any immunity against the virus.
No difference between viral RNA of vaccinated and unvaccinated monkeys
"All of the vaccinated monkeys treated with the Oxford vaccine became infected when challenged as judged by recovery of virus genomic RNA," former Harvard professor Dr. William Haseltine said, while noting that the viral RNA loads in vaccinated monkeys also matched that of unvaccinated ones.
Virus severity reduced in the animals
Even though the vaccine did not stop the virus from infecting the monkeys, it did manage to reduce its severity. The study results suggest that the monkeys who got the vaccine did not display symptoms of pneumonia. It is said to be 'encouraging' for partial protection, but there is no way to say if the same would be true for humans, too.
It may not work on humans, per experts
Overall, the data from the failed monkey challenge test has led experts to suggest that the vaccine may not work on humans. "That viral loads in the noses of vaccinated and unvaccinated animals were identical is very significant," Jonathan Ball, a professor of molecular virology at the University of Nottingham tweeted. "If the same happened in humans, vaccination would not stop [the] spread."
For now, clinical trials are still going on
As of now, the human trials of the experimental vaccine are moving forward, with no comment from the UK government or Oxford on the implications of these findings on the ongoing vaccine research. However, given that successful animal testing is a significant benchmark for proceeding with human trials, we expect urgent re-appraisal of the ongoing tests in Britain.
