Dr. Anthony Fauci, the director of the National Institute of Allergy and Infectious Diseases, told lawmakers that while one can "never guarantee the safety or effectiveness" of a vaccine, he is "cautiously optimistic" that the coronavirus vaccine being developed by Moderna and his agency will be successful.
"We hope that by the time we get into late fall and early winter, we will have in fact a vaccine that we can say that would be safe and effective. One can never guarantee the safety or effectiveness unless you do the trial, but we are cautiously optimistic this will be successful," Fauci said.
"Because in the early studies with humans, the phase one study, it clearly showed that individuals who are vaccinated mounted a neutralizing antibody response that was at least comparable and in many respects better than what we see in convalescent serum from individuals who have recovered from Covid-19," Fauci added.
Some background: The phase three clinical trial of the vaccine discussed by Fauci began Monday.
The investigational vaccine was developed by the biotechnology company Moderna and the National Institute of Allergy and Infectious Diseases, part of the National Institutes of Health. The trial will be conducted at nearly 100 US research sites, according to Moderna. The first patient was dosed at a site in Savannah, Georgia.
The trial is expected to enroll about 30,000 adult volunteers and evaluates the safety of the Moderna/NIH vaccine and whether it can prevent symptomatic Covid-19 after two doses, among other outcomes.
Volunteers will receive either two 100-microgram injections of the vaccine or a placebo about 28 days apart. Investigators and participants will not know who has received the vaccine.