Moderna's COVID-19 vaccine candidate shows promise in older adults

Interim data from a Phase I study presented by Moderna on Wednesday showed that its experimental vaccine mRNA-1273 was safe and generated an immune response in people over the age of 55. Results from cohorts of older adults aged 56 to 70 years, as well as elderly participants 71 years and older, were detailed at the US Centers for Disease Control and Prevention's Advisory Committee on Immunization Practices.

The new findings build on interim data published in the NEJM last month demonstrating that a two-dose vaccination schedule of mRNA-1273, administered via intramuscular injections given 28 days apart, induced anti–SARS-CoV-2 immune responses, including antibody and T-cell responses, in all 45 healthy younger volunteers aged 18 to 55 years.

Moderna is testing mRNA-1273 in 20 subjects enrolled in each of the two older population groups. The interim data presented Wednesday is on 10 adults between the ages of 56 and 70, and 10 elderly adults aged 71 and older, with each participant receiving two 100-mcg doses of the vaccine 28 days apart.

Titers comparable across age groups

The company reported that pseudovirus (PsV) neutralisation responses were detected in all participants out to day 57, one month after the second dose, with geometric mean antibody titers (GMT) of 267, 324 and 242, respectively, for the younger adult, older adult and elderly cohorts. Moderna said "PsV titers were comparable across age groups," and that median titers for both the older adult and elderly populations were higher than those seen in patients who had recovered from COVID-19. It added that vaccination with mRNA-1273 at 100 mcg also led to a Th1-biased CD4+ T-cell response across all age groups, while the Th2 phenotype was rare.

In addition, the company said its vaccine appeared to be well tolerated, with no serious adverse events, although some participants did report fatigue, chills, headaches and pain at the injection site, but the majority of symptoms resolved within two days.

"These data are consistent with our perspective that responses in older patients after mRNA-1273 treatment will likely be in line with what was seen in younger populations," commented SVP Leerink analyst Mani Foroohar, "and while safety signals may emerge in larger studies/with longer follow-up, this applies across all age groups." Last month, Moderna initiated the Phase III COVE trial testing how safe and effective mRNA-1273 is on 30,000 people with results expected as early as October. 

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