Investigational COVID-19 vaccine shows strong immune response in older adults


A phase 1 trial of an investigational mRNA vaccine to prevent SARS-CoV-2, the virus that causes the novel coronavirus (COVID-19), has shown that the vaccine is well-tolerated and generates a strong immune response in older adults, according to a report published today in the New England Journal of Medicine.

The experimental vaccine, mRNA-1273, was co-developed by researchers at the National Institute of Allergy and Infectious Diseases (NIAID) and Moderna, Inc. in Cambridge, Massachusetts. The phase 1 trial began on March 16, 2020 and was expanded to enroll older adults about one month later.

In its expansion to include older adults, the trial enrolled 40 healthy volunteers: 20 adults ages 56 to 70 years, and 20 adults ages 71 years and older. Ten volunteers in each age group received a lower dose of the vaccine (25 μg), and 10 volunteers in each age group received a higher dose (100 μg).

After approximately one month, volunteers then received a second dose of the same vaccine at the same dosage. Throughout the study, volunteers attended clinic visits to track their responses to the vaccine and assess safety.

Older adults are more vulnerable to complications of 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 researchers said.

Overall, the researchers found that the investigational vaccine was well-tolerated in this older age group. Although some volunteers experienced some transient adverse effects, including 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 binding and neutralizing antibodies against SARS-CoV-2, the researchers said. Importantly, the immune response to the vaccine seen in older volunteers was comparable to that seen in younger age groups.

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

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