Drugmakers use the media to tout coronavirus treatments that are still under review

Vaccine maker Moderna attracted glowing headlines and bullish investors when it revealed that eight participants in a preliminary clinical trial of its coronavirus vaccine had developed antibodies to the virus. The company's share price jumped nearly 20 percent that day as it released a massive stock offering.

But the full results of the 45-person safety study haven't been published, even though Moderna began a second, larger trial in late May aimed at determining whether the vaccine works. Several vaccine researchers say the scant public information on the earlier safety study is hard to evaluate because it addresses less than 20 percent of participants.

Call it science by press release - a tactic that pharmaceutical companies are increasingly relying upon to set their experimental coronavirus drugs and vaccines apart in a crowded field, shape public opinion and court regulators. Public health experts say the approach could increase political pressure on federal health officials to green-light drugs and vaccines before it is clear they are safe or effective, with potentially dangerous consequences.