Investigational mRNA vaccine to prevent SARS-CoV-2 shows promise in older adults

reviewed by Emily Henderson, Bachelor of ScienceSeptember 30, 2020

A phase 1 trial of an investigational mRNA vaccine to prevent SARS-CoV-2 infection has shown that the vaccine is well tolerated and elicits a strong immune response in older adults. A report published today in the New England Journal of Medicine describes the findings of the study, which was supported by the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health. SARS-CoV-2 is the virus that causes COVID-19 disease.

The experimental vaccine, mRNA-1273, was developed jointly by researchers at NIAID and Moderna, Inc. of Cambridge, Massachusetts. The phase 1 trial began on March 16, 2020 and was expanded to enroll older adults about a month later. Older adults are more vulnerable to complications from COVID-19 and are an important population for vaccination. Understanding how the vaccine affects older adults is a critical part of measuring its safety and efficacy.

The trial was conducted at the Kaiser Permanente Washington Health Research Institute (KPWHRI) in Seattle, Emory University in Atlanta, and the NIAID Vaccine Research Center (VRC) clinic at the United States Clinical Center. NIH in Bethesda, Maryland. Julie Ledgerwood, DO, deputy director and medical director of the VRC, supervised the study at the NIH site. The Coalition for Innovations in Epidemic Preparedness (CEPI) supported the manufacture of the vaccine candidate for this trial. This trial is supported by the Infectious Diseases Clinical Research Consortium (IDCRC) through NIAID.

In its expansion to include older adults, the trial enrolled 40 healthy volunteers: 20 adults ages 56 to 70 and 20 adults 71 and older. Ten volunteers from each age group received a lower dose of the vaccine (25 μg) and 10 volunteers from each age group received a higher dose (100 μg). After about a month, the volunteers received a second dose of the same vaccine in the same dose. Throughout the study, volunteers attended clinic visits to track their responses to the vaccine and assess safety.

Overall, the researchers found that the investigational vaccine was well tolerated in this older age group. Although some volunteers experienced some transient adverse effects, such as fever and fatigue after vaccination, the researchers found that they also exhibited a good immune response to the vaccine: the blood of vaccinated volunteers contained robust neutralizing and binding antibodies against SARS-CoV -two. Importantly, the immune response to the vaccine observed in older volunteers was comparable to that observed in younger age groups.

The study will continue to follow older volunteers for about a year after the second vaccination to monitor the long-term effects of the vaccine. According to the researchers, the results of these phase 1 trials further support the investigational vaccine trials in older adults in a large ongoing phase 3 trial.