A coronavirus vaccine produced by researchers at Oxford University started Phase 1 trials involving around 1,000 people last month. Today, those trials advanced to the next stage of human trials involving many more volunteers.

An experimental vaccine for COVID-19 under development at Oxford University hit a milestone Friday with researchers announcing it will be progressing to advanced stages of human trials.

It will be tested in 10,260 volunteers across the United Kingdom to determine how effective it is at preventing infection, the university said in a statement. If successful, it could be on the market as early as September, according to British-Swedish drugmaker AstraZeneca, which partnered with the university in April to manufacture and distribute the vaccine…

The company agreed to produce at least 400 million doses and secured total manufacturing capacity to produce 1 billion doses by the end of 2021, with first deliveries this September.

In a press release, the Oxford group said Phase 2 of the testing would also involve expanding the age range of the people being tested, including to those over 70-years-old. Professor Andrew Pollard who is leading the research said, “The clinical studies are progressing very well and we are now initiating studies to evaluate how well the vaccine induces immune responses in older adults, and to test whether it can provide protection in the wider population.”

The Oxford vaccine is based on a version of the common cold virus which has been manipulated so that it cannot spread in humans. A small test in rhesus macaques was performed in March. Just six monkeys were tested but researchers found some benefit from the vaccine:

Researchers reported at least some of the monkeys developed antibodies to the virus within 14 days of being vaccinated, and all of the vaccinated animals had evidence of antibodies within 28 days.

What’s more, researchers said the vaccine appears to have prevented pneumonia and other lung problems in the animals after they were exposed to the coronavirus.

However, that small study was a pre-print, meaning it has not been peer-reviewed yet. Also, the findings may not be all that impressive because the vaccine didn’t actually prevent any of the dosed monkeys from getting the infection.

All of the vaccinated monkeys treated with the Oxford vaccine became infected when challenged, as judged by recovery of virus genomic RNA from nasal secretions. There was no difference in the amount of viral RNA detected from this site in the vaccinated monkeys as compared to the unvaccinated animals. Which is to say, all vaccinated animals were infected. This observation is in marked contrast to the results reported from Sinovac trial. At the highest dose studied, no virus was recovered from vaccinated monkeys from the throat, lung, or rectum of the vaccinated animals.

There is a second troubling result of the Oxford paper. The titer of neutralizing antibody, as judged by inhibition of virus replication by successive serum dilutions as reported is extremely low. Typically, neutralizing antibodies in effective vaccines can be diluted by more than a thousand fold and retain activity. In these experiments the serum could be diluted only by 4 to 40 fold before neutralizing activity was lost. Again, by contrast the titer of neutralizing antibodies in the serum of those vaccinated with whole inactivated SARS-CoV-2 was high.

That doesn’t sound very successful to me but there is some evidence from examination of the monkeys post-infection, that the vaccine may have helped prevent the onset of pneumonia. Still, this was a very small study so it’s way too early to draw big conclusions.

CNN has an interview with two of the subjects of the trial who are obviously hoping this vaccine doesn’t turn out to be a failure.