TUESDAY, Sept. 29, 2020 (HealthDay News) -- One of the big questions around any new COVID-19 vaccine is: Will it safely protect those at highest risk from the illness -- older people?
Now, the results of an early phase 1 trial in 40 adults over the age of 55 suggests that one vaccine, under development by drugmaker Moderna, elicits an immune system response that's equal to that seen in younger recipients.
As well, vaccine side effects "were predominantly mild or moderate in severity" and included fatigue, chills, headache or ache or discomfort at the injection site, according to the researchers.
They published the preliminary findings Sept. 29 online in the New England Journal of Medicine.
"As those at highest risk for severe COVID-19 infection are older adults, it is crucial to understand how well the vaccine works in this age group," explained Dr. Amesh Adalja, an expert unconnected to the trial.
"This early phase 1 study appears to be promising, but it is not possible to know definitively until phase 3 data is available," said Adalja. He's a senior scholar at the Johns Hopkins Center for Health Security in Baltimore.
The new study focused on an experimental Moderna vaccine called mRNA-1273. The two-dose vaccine is in late-stage trials and Moderna has said it hopes to have the vaccine ready for widespread use by year's end.
However, "among different risk factors, advanced age has been recognized from the beginning as associated with poorer outcomes" from a vaccine, noted Dr. Bruce Hirsch, an attending physician in infectious diseases at Northwell Health in Manhasset, N.Y.
So, "doctors are worried that those who need this vaccine the most may respond to the vaccine the least," he said.
To help answer the issue, a team led by researchers at Emory University in Atlanta looked specifically at immune response and side effect data for 40 patients, aged 56 and above, enrolled in the mRNA-1273 trial.
They observed a rapid uptick in coronavirus-specific immune system antibodies in these older people soon after they'd gotten their first shot. Those numbers rose even higher after the second shot was administered.
Most importantly, antibody responses in the over-55 group "appeared to be similar to those previously reported among vaccine recipients between the ages of 18 and 55," the researchers noted.
Other immune system markers, such as levels of T-cells and proteins called cytokines, also appeared "strong" in response to the vaccine.
Side effects could occur after vaccination, but they were similar to those sometimes seen in people who get the flu shot -- transient fatigue, chills and headache, for example.
Dr. Eric Cioe-Pena is an emergency physician at Staten Island University Hospital in New York City. Reading over the findings, he agreed that "though the data is limited, this phase 1 study does demonstrate safety in older adults, which is an important target population."
Still, Hirsch stressed that the study's small size means caution is still needed.
"The vaccine's ability to protect against actual infection in the real world is yet untested," Hirsch said, and "this study leaves unanswered how durable will be the immunity. Still, this preliminary data is reassuring as we look forward to getting a handle on this pandemic."
The U.S. Centers for Disease Control and Prevention has more on the new coronavirus.
SOURCES: AmeshAdalja, M.D., senior scholar, Johns Hopkins University Center for Health Security, Baltimore; Eric Cioe-Pena, M.D., emergency physician, Staten Island University Hospital, New York City, and director, Global Health, Northwell Health; Bruce Hirsch, M.D., attending physician, infectious diseases, Northwell Health, Manhasset, N.Y.; New England Journal of Medicine, Sept. 29, 2020