Illustration: Aïda Amer/Axios

New clinical trial data from two experimental coronavirus vaccines — one from Oxford University and AstraZeneca in the United Kingdom, and the other from CanSino Biologics in China — are providing cautious optimism in the race to combat the pandemic.

The big picture: Science has never moved this fast to develop a vaccine. And researchers are still several months away from a clearer idea of whether the leading candidates help people generate robust immune responses to this virus.

Driving the news: The Oxford and CanSino vaccines didn't lead to any severe adverse reactions or hospitalizations, according to the results released yesterday.

  • Safety — not efficacy — was the main thing these studies were supposed to be testing. And they performed well enough to move on to further trials.
  • Competing candidates from Moderna and Pfizer/BioNTech have also performed well in safety trials.

Yes, but: Future trials will be the ones that tell us whether any of these potential vaccines actually trigger patients' immune systems to respond to the virus.

  • In the results released yesterday, Oxford researchers gave their vaccine to 543 people but only tested 35 for "neutralizing antibodies." A separate, nonrandomized group of 10 people got a booster dose of the Oxford vaccine a month after the initial dose.
  • Preliminary antibody responses from CanSino's vaccine were "disappointing" to several experts.

"It's a lot of hype," said Paul Offit, a physician and vaccine expert at Children's Hospital of Philadelphia. "It's just trying to read the tea leaves of what will be a large phase three trial."

The bottom line: There are 23 coronavirus vaccines in clinical testing right now, according to the World Health Organization.

  • We now have data on the first four, but the studies mostly are confirming that the vaccines aren't severely harmful and that large-scale studies are warranted — not that they definitely work yet.
  • "It is good and hopeful news indeed, but we'll only know when the large trials are done," tweeted Robert Califf, a former FDA commissioner under Barack Obama.

Go deeper: Read more about the state of the global race for a vaccine

Go deeper

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Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said Friday that the chances of a coronavirus vaccine having 98% or more guaranteed protection are "not great," per CNBC.

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Data: The Center for Systems Science and Engineering at Johns Hopkins; Map: Axios Visuals

African countries collectively surpassed 1 million confirmed coronavirus cases this week.

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Coronavirus dashboard

Illustration: Sarah Grillo/Axios

  1. Global: Total confirmed cases as of 2 p.m. ET: 19,451,097 — Total deaths: 722,835 — Total recoveries — 11,788,665Map.
  2. U.S.: Total confirmed cases as of 2. p.m. ET: 4,968,413 — Total deaths: 161,858 — Total recoveries: 1,623,870 — Total tests: 60,415,558Map.
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