In April I wrote about vaccine development for COVID-19. That article outlines some of the background information you might want to read if you are not familiar with this topic. At the time the frontrunner, the Moderna messenger ribonucleic acid (mRNA) vaccine, had been in trials for about a month. This week the New England Journal of Medicine (NEJM) published an article outlining the phase I trial of the Moderna vaccine against COVID-19.
The vaccine was given to 45 healthy adults ranging from 18 to 55 years of age, as two injections given 28 days apart, with mRNA-1273. The vaccine was developed by researchers at the National Institute of Allergy and Infectious Diseases (NIAID, the trial sponsor) and at Moderna (Cambridge, MA). Participants were enrolled at Kaiser Permanente in Seattle, Washington, and Emery University in Atlanta, Georgia.
Researchers measured blood levels of antibody responses in the participants. Recall that antibodies are the tiny molecules our immune system produces to protect us from reinfection by an invader such as a virus at some point in the future. Think of them as a sort of weapon the body uses.
In this study, following the second injection “serum-neutralizing activity was detected.” In other words, antibodies that would neutralize SARS-CoV-2 were seen in all participants. Side effects including fatigue, chills, headache, muscle aches, and pain at the injection site were reported in more than half, though none significant enough to limit the trial were detected.
Researchers found that a type of so-called binding antibody called IgG against the viral spike protein increased rapidly after the first vaccination in all participants by day 15. After the second vaccine all participants likewise produced a volume of antibody similar to that seen in patients who produce convalescent serum. That implies a good immune response, what you need to stop an infection. For more on that topic, see this MPDN article. And, in case you are wondering, the participants were also tested for antibodies prior to vaccination, and all found to have no detectable antibodies, indicating antibody formation was all but certainly due to vaccine exposure.
Finally, a type of immune cell in the blood called the CD4 T-cell was activated by the vaccine, again indicating a robust immune response.
A large phase III efficacy trial is starting at the end of July to determine if the vaccine is effective.
To listen to a 7/17/20 podcast (or read the transcript) of Drs. Anthony Fauci, Abraham Verghese, and Eric Topol discussing this and other topics on Medicine and the Machine, please click here.
