Here’s a bright spot in a summer of otherwise discouraging coronavirus news: The race for a vaccine is going about as well as anyone could have expected. That’s despite the United States reaching the grim milestone of roughly 150,000 deaths from the novel virus. It’s been six months since China first posted online the genetic sequence of the novel coronavirus. Yet already three companies have launched final-stage clinical trials for a vaccine – at record speed, by any standard – and another is on the verge of doing so.

This month, U.S. companies Moderna and Pfizer launched final Phase 3 trials involving tens of thousands of volunteers. A third company, AstraZeneca, partnered with Oxford University in the United Kingdom, has already been conducting final-stage trials for weeks. And a Chinese company, CanSino Biologics, is expected to announce Phase 3 trials next month.

These developers have found promising early results, allowing them to embark upon Phase 3 clinical trials in record time.

Their success keeps opening the possibility of a vaccine being ready for wide dissemination in early 2021, although that also depends on countries having the infrastructure to administer shots to millions of people.

“The data so far has been on the high end of expectations,” Ronny Gal, a financial analyst with investment research firm Sanford C. Bernstein and Co., told me.

Anthony S. Fauci, director of the National Institute of Allergy and Infectious Disease, offered a similar analysis. On Monday, he told CNN he’s “cautiously optimistic” about the Moderna vaccine, which is being developed in collaboration with the National Institutes of Health.