Sept. 28 (UPI) -- More than half of all clinical trials evaluating vaccines and potential treatments for COVID-19 are "at high risk for excluding older adults," according to an analysis published Monday by JAMA Internal Medicine.
In addition, roughly one in four of the 847 trials reviewed by the researchers included an age "cutoff" that would exclude adults age 65 to 80, the data showed.
Older adults are generally considered to be at higher risk for severe COVID-19 and health complications related to the disease, research suggests.
"Based on our study, older adults, particularly those in their 70s and 80s, may be systematically excluded from the clinical trials necessary to develop and test [COVID-19 vaccines and treatments]," study co-author Dr. Sharon Inouye told UPI.
"My biggest concern is that without clinical trial testing, older adults will ultimately be denied treatments and vaccines -- as a result, equitable distribution to this population will not be possible, and this will be an egregious oversight," said Inouye, director of the Aging Brain Center at the Marcus Institute for Aging Research in Boston.
Adults 60 and older accounted for just under 20% of new COVID-19 cases across the country in August, down from just under 30% in May, according to estimates from the U.S. Centers for Disease Control and Prevention.
The decline has been attributed to enhanced prevention measures implemented to lower the risk for older adults after the disease swept through nursing homes in the spring.
Still, adults 65 and older have made up about 40% of those hospitalized and 80% of those who die from COVID-19, Inouye said.
For the analysis, she and her colleagues evaluated 847 trials active as of August, identifying those with age exclusions listed in their respective participant eligibility and exclusionary criteria.
Overall, 195 -- or 23% -- included an age "cut-off" or upper age limit, the researchers said.
Only 30% of the trials assessed did not have any aged-based exclusion criteria -- meaning no age groups were prevented from participating -- according to the researchers.
Fifty-three percent of the trials had either age-based exclusions or exclusions "preferentially affecting older adults," which placed them at "high risk for excluding older adults," the researchers said.
Of the 232 Phase 3 trials -- the final stage in the drug or vaccine evaluation process -- 38, or 16%, included age cutoffs and 77, or 33%, had exclusions preferentially affecting older adults, they said.
Of the 18 vaccine trials, 11, or 61%, included age cutoffs and seven "had broad non-specified exclusions," placing all at "high risk for excluding older adults," according to the researchers.
"[Older adults] are the target group where the treatments and vaccines are essential, and yet they are being excluded from the clinical trials," Inouye said. "What this means is that strategies to maximize and ensure effectiveness in these populations, and testing for safety will be limited in older adults."