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Small Trial in Older Recipients: Few Issues With Moderna COVID-19 Vaccine

Older Americans make up a substantial percentage of those receiving COVID-19 vaccines in the early stages, and many might have questions about safety and efficacy in their age group. A small trial of the Moderna vaccine, which received emergency use authorization from the FDA, offers some data specific to those 56 and older. Here is more information.

ATLANTA – One of the concerns in developing vaccines for COVID-19 is that the immune response to many other vaccines has been shown to decrease with increasing age.

A study published in the New England Journal of Medicine also points out that “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.”

The information also is of significant concern to pharmacists, who already are playing a key role in vaccine distribution by immunizing long-term care facility residents in most states and the broader population of older people in some states.

Researchers from the Emory University School of Medicine and Children’s Healthcare of Atlanta report preliminary safety and immunogenicity data for the mRNA-1273 vaccine in an expansion of the phase 1 trial among healthy participants who were 56 years of age or older. The vaccine, developed by Moderna in conjunction with federal health authorities, was given emergency use authorization in December by the Food and Drug Administration for use in those 18 and older.

“In our study population of older participants (≥56 years of age), the two-dose vaccine series had an acceptable safety and reactogenicity profile at doses of both 25 μg and 100 μg with mostly mild-to-moderate local and systemic adverse events of short duration, which occurred predominantly after the second dose,” the study team reports, adding, “We did not observe systematic differences in the reactogenicity profile between this older cohort and participants between the ages of 18 and 55 years who had received the mRNA-1273 vaccine.”

The authors add that their findings were similar to the results of other trials of mRNA vaccines involving younger adults.

The phase 1, dose-escalation, open-label trial involved the messenger RNA vaccine, mRNA-1273, which encodes the stabilized prefusion SARS-CoV-2 spike protein (S-2P) in healthy adults. Researchers point out that the trial was expanded to include 40 older adults, who were stratified according to age (56 to 70 years or ≥71 years). All the participants were assigned sequentially to receive two doses of either 25 μg or 100 μg of vaccine administered 28 days apart.

They advise that solicited adverse events were predominantly mild or moderate in severity and most frequently included fatigue, chills, headache, myalgia, and pain at the injection site.

The study found that adverse events were dose-dependent and tended to be more common after the second immunization.

“Binding-antibody responses increased rapidly after the first immunization. By day 57, among the participants who received the 25-μg dose, the anti–S-2P geometric mean titer (GMT) was 323,945 among those between the ages of 56 and 70 years and 1,128,391 among those who were 71 years of age or older; among the participants who received the 100-μg dose, the GMT in the two age subgroups was 1,183,066 and 3,638,522, respectively,” according to the report.

In fact, after the second immunization, serum neutralizing activity was detected in all the participants by multiple methods, according to the study team, which adds that the vaccine elicited a strong CD4 cytokine response involving type 1 helper T cells.

“In this small study involving older adults, adverse events associated with the mRNA-1273 vaccine were mainly mild or moderate,” the authors conclude. “The 100-μg dose induced higher binding- and neutralizing-antibody titers than the 25-μg dose, which supports the use of the 100-μg dose in a phase 3 vaccine trial.”