Moderna’s experimental coronavirus vaccine stimulated an immune response in older patients in an early-stage clinical trial without causing serious side effects, according to a medical journal article on the two-shot regimen now being tested on up to 30,000 people in a late-stage study.
The vaccine developed by Cambridge-based Moderna and the National Institute of Allergy and Infectious Diseases produced antibodies and white blood cells known as T cells in 40 volunteers, the New England Journal of Medicine said in an article posted online Tuesday. Half of the participants were 56 to 70 years old, and the other half were 71 or older.
The levels of antibodies and T cells were higher in the 20 individuals who received two 100-microgram doses than in the 20 who got two 25-microgram doses. Each volunteer received shots 28 days apart.
Moderna is now testing the higher dose in a Phase 3 trial at 100 sites across the country. Some 27,232 volunteers have enrolled in the study so far, with half getting the vaccine and half getting a placebo, according to figures posted last Friday on the firm’s website. A total of 15,454 participants have received their second vaccination. The experimental coronavirus vaccine is one of 11 by drug companies in late-stage trials.
The article in the New England Journal of Medicine expands on information Moderna shared last month with an advisory committee of the Centers for Disease and Control and Prevention. The findings are encouraging because COVID-19 has proven particularly lethal in older people, and vaccines often prove less effective in the elderly.
“The immune response to many other vaccines has been shown to decrease with increasing age,” said the journal article. “Thus, the testing of SARS-CoV-2 vaccine candidates in older populations is of paramount importance, since these persons account for the majority of serious COVID-19 cases and associated deaths.”
In the study, the vaccine induced “high levels” of two kinds of antibodies in blood samples taken from the older volunteers, and the antibody levels resembled those found in the blood of 45 younger people who had participated in a previous early-stage trial of Moderna’s vaccine, according to the peer-reviewed article.
In addition, the antibody levels after the second dose resembled those found in the blood of patients who recovered from COVID-19.
There were some side effects, but they were generally mild or moderate. The most common were headache, fatigue, muscle aches, chills, and pain around the injection site.
Moderna is one of several drug makers working on a coronavirus vaccine that employs messenger RNA technology, a promising approach that has never led to an approved vaccine. Messenger RNA is the molecule that relays genetic instructions from DNA to the protein-making machinery of human cells. The COVID-19 vaccine is supposed to teach the body to produce viral proteins after injection, prompting the immune system to react and build up antibodies that would protect recipients against the real virus.
A New England Journal of Medicine article in mid-July reported that the Moderna vaccine generated immune responses in all 45 healthy subjects who received it, although it caused mild side effects in some of them. Three groups of 15 volunteers between the ages of 18 and 55 received varying dosage.
Given the outsize toll that COVID-19 has taken on older people, the National Institute of Allergy and Infectious Diseases expanded the early-stage trial to include 40 older adults. The expanded trial was conducted at Kaiser Permanente Washington Health Research Institute in Seattle, the Emory University School of Medicine in Atlanta, and the NIAID Vaccine Research Center in Bethesda, Md.
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