The most promising coronavirus vaccine candidate shows yet more positive results

The Oxford vaccine, which goes by the unpronounceable moniker "ChAdOx1 nCoV-19 (AZD1222)," is being developed with the assistance of a British-Swedish pharmaceutical company known as AstraZeneca, according to an article recently published in The Lancet. The study involved 1,077 volunteers and in its early-stage human trials was shown to be safe and stimulate a strong immune response. Andrew Pollard, the lead author of the study, said in a statement that the researchers hope "this means the immune system will remember the virus, so that our vaccine will protect people for an extended period."

He added, "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."

The authors noted that the most common reported systemic reactions were fatigue and headache, and that other negative side effects included feverishness, muscle ache and malaise.

"Our preliminary findings show that the candidate ChAdOx1 nCoV-19 vaccine given as a single dose was safe and tolerated, despite a higher reactogenicity profile than the control vaccine, MenACWY," the authors wrote. Reactogenicity means the tendency of a shot to produce common adverse reactions, like a sore arm or mild fever. "No serious adverse reactions to ChAdOx1 nCoV-19 occurred," they add. "The majority of adverse events reported were mild or moderate in severity, and all were self-limiting."

The World Health Organization reports that there are currently 23 potential vaccines being tested in human trials, with more than 130 others in preclinical studies. In addition to the Oxford study, The Lancet reported that a Chinese vaccine is also showing modest, positive results.

In an editorial, The Lancet pointed out that there are many additional steps beyond the clinical trials, even if they prove fruitful.

"While vaccine development research continues, questions are already arising on the next steps and challenges, concerning the manufacturing, distribution, and widespread accessibility of a possible vaccine," the editorial warned. "Some strategies are already being considered: Sandy Douglas at the University of Oxford, for example, is leading the ChAdOx1 nCoV-19 vaccine manufacturing scale-up project. Working immediately on large-scale production could accelerate the availability of a high-quality and safe vaccine when the right candidate is there."

In addition, as Oxford University notes on its website, "'Translational medicine' - taking discoveries from the laboratory right through to treatments for patients — is a significant focus of medical research at Oxford. This 'bench to bedside' approach is aided by fruitful links with NHS [National Health Service] organisations."

One possible threat to the success of any vaccine, at least in the United States, is that a large number of people may not get it and thereby threaten our ability to develop herd immunity. A survey last month by The Washington Post and ABC News found that only 43 percent of Americans would definitely get vaccinated and only 28 percent would probably do so. By contrast, 12 percent said they probably would not and 15 percent said they definitely would not.

"We very clearly know that, if we don't get 70-something percent of the population covered, we will probably not get to herd immunity," Dr. Georges Benjamin, executive director of the American Public Health Association, told Salon in May when discussing the struggle to achieve herd immunity. "There are some people that think that, with this virus, we might be able to achieve it with 50 percent, so that's not 100 percent. But I'm thinking that 70-something percent is about where we need to be, and it's because I've looked at some of the data. We may achieve it with 50 percent, but the bottom line is we'd run the risk of not getting herd immunity with the vaccine."