"We didn't see any events that are characterized as serious adverse events," said lead author Dr Lisa Jackson of Kaiser Permanente Washington Health Research Institute in Seattle, referring to reactions that require hospitalization or result in death. In June, Moderna said it selected the 100-microgram dose for its late-stage study to minimize adverse reactions. At that dose, Moderna said the company is on track to deliver about 500 million doses per year, and possibly up to 1 billion doses per year, starting in 2021, from the company's internal US manufacturing site and strategic collaboration with Swiss drugmaker Lonza. "It's a good first step," said Dr William Schaffner, a vaccine expert at Vanderbilt University Medical Center who was not involved in the study. "There's nothing here that would inhibit one from going ahead to the Phase 2/Phase 3 trials," he said.