Healthy Clinical Trial Subjects Suffer Grade 3 Side Effects to Moderna’s mRNA COVID-19 Vaccine
On May 18, 2020, Moderna, Inc. of Cambridge, Massachusetts announced that it had obtained “positive interim clinical data” from a Phase I human clinical trial of its experimental mRNA-1273 COVID-19 vaccine that began on Mar. 16. The biotechnology company said that eight of the 45 healthy adult volunteer trial subjects developed antibodies that may provide protection from the SARS-CoV-2 virus that causes COVID-19.1 2 3 The company also reported that four participants suffered Grade 3 vaccine reactions.
Severe Adverse Events Reported After One or Two Vaccine Doses
Each of the 45 participants was given two doses of the Moderna vaccine about a month apart. The dosage levels were 25, 100 or 250 micrograms (µg). Moderna said that the four participants who received doses of 25 µg developed antibodies against SARS-Cov-2 about two weeks after the second dose was administered and that the same was true for the four participants given doses of 100 µg. The company noted that the vaccine was “generally safe and well tolerated.”1 2
The mRNA-1273 vaccine reportedly produced a “Grade 3 adverse event” in one participant among those who received doses of between 25 µg and 100 µg doses. That person experienced Grade 3 erythema or a rash around the injection site. A Grade 3 rash can mean blistering, open ulcers, wet peeling (moist desquamation) or a serious rash over large areas of the body.4 5
Three participants in the clinical trial who received a vaccine dose of 250 µg doses experienced “Grade 3 systemic symptoms” following administration of the second dose. Moderna described these as the “most notable” of the adverse events and said that they had been “transient and self-resolving.”1 2