Scientists at the Jenner Institute at Oxford University have a head start on developing an effective vaccine against the deadly COVID-19. They're testing a vaccine that's already been proven harmless to humans in previous trials on an earlier version of the coronavirus.

That's helped them forge ahead to schedule tests on human volunteers to prove it's safe and effective. According to The New York Times, if the scientists get fast-track approval from regulators, they could roll out a few million doses by September, months before a vaccine has been anticipated, providing the initial testing shows that it works.

Recent evidence about its efficacy is encouraging. Scientists at the National Institutes of Health's Rocky Mountain Laboratory in Montana inoculated six rhesus macaque monkeys with single doses of the Oxford vaccine.

They infected the monkeys with large quantities of the novel coronavirus, a dose that sickened other monkeys at the same facility. But more than 28 days later, according to the Times, all six were healthy.

While there is no guarantee that the monkey results will parallel human trials, rhesus macaque monkeys are "the closest thing we have to humans," said Dr. Vincent Munster, the researcher who conducted the test. According to the Times, the monkey results will help accelerate Oxford's efforts to come up with a vaccine.

"It is a very, very fast clinical program," noted Emilio Emini, a director of the vaccine program at the Bill and Melinda Gates Foundation, which is funding many competing efforts. Human trials on 1,110 human volunteers began April 23 on the Oxford vaccine and are expected to be finished by September.

Meanwhile, the world’s largest vaccine maker, the Serum Institute of India, said it would not wait for the trial to end and already was making 40 million doses to save time in case it worked.