The race is on to develop an effective vaccine for the coronavirus. A very early research trial has sent ripples across the scientific community, offering cautionary hope for a successful outcome.
According to data from the Milken Institute, there are currently 140 vaccine candidates in various stages of development. Among them is the mRNA-1273 that is under development by Moderna, a biotech company based in Massachusetts.
What does the data show?
The vaccine is currently in phase I of human clinical trials, which involves evaluating the safety and immunogenicity of several different doses. The study is being led by the National Institute of Allergy and Infectious Diseases, part of the National Institutes of Health. Overall, the vaccine was found to elicit a strong immune response in eight healthy volunteers.
Data on the immune response are currently available for the 25 µg and 100 µg dose level (ages 18-55) after two doses (day 43) and at the 250 µg level (ages 18-55) after one dose (day 29). In a press release, Moderna reports that dose dependent increases in immunogenicity were observed in all three doses. All 45 participants who were enrolled produced binding antibodies that were at levels similar to those of people who have recovered from the virus. The vaccine was also generally safe and well-tolerated among all participants.
Proceeding with caution
But while promising, the results are limited. Some vaccine experts have expressed skepticism over the data. Based on the given information, experts say its effectiveness cannot be adequately assessed. The results on neutralizing antibodies were available for only eight participants, and the blood was tested two weeks after the vaccine was given—thus, there are no data on durability. Moderna also states that the observed antibody levels were on par with or higher than that seen in people who recovered from the virus, but antibody levels among people who have recovered can vary enormously.
The results must now be repeated in larger trials to see if the vaccine is safe and effective in the “real world,” and Moderna expects to initiate phase III trials in July.