Starting this month, and adding a new vaccine’s trial each month, a group of 30,000 younger USA citizen volunteers will get a trial vaccine for Covid-19. Some vaccines will require two doses.
150,000 in total have expressed interest in being in a vaccine trial.
After volunteers get two doses a month apart, scientists will closely track which group experiences more infections as they go about their daily routines, especially in areas where the virus is spreading unchecked.
The answer probably won't come until November or December, cautioned Dr. Anthony Fauci, NIH's infectious-diseases chief.
Among many questions the study may answer: How much protection does just one dose offer compared with the two scientists think are needed? If it works, will it protect against severe disease or block infection entirely?
Don't expect a vaccine as strong as the measles vaccine, which prevents about 97% of measles infections, Fauci said, adding he would be happy with a COVID-19 vaccine that's 60% effective.
Several other vaccines made by China and by Britain's Oxford University began smaller final-stage tests in Brazil and other hard-hit countries earlier this month. But the U.S. requires its own tests of any vaccine that might be used in the country.
