Residents’ weakened immune systems could dilute the effectiveness of future coronavirus vaccines in the most vulnerable population, according to a new report.

The decline, called immunosenescence, already undermines elders’ response to other vaccines. This in turn can raise mortality risk in illnesses such as flu. Health officials and scientists are concerned that it could pose similar problems for COVID-19 vaccines, according to the Wall Street Journal.

Researchers are responding to the issue by proposing options such as increased doses or adding booster shots (adjuvants) for older adults, strategies already used with flu vaccines. Some drug firms, such as Pfizer, Inc., are testing vaccine candidates in older adults. At least one vaccine for the elderly is in development, the news outlet reported.

“It would not be particularly encouraging if we have a vaccine that’s capable of protecting 20-year-olds who probably have a pretty low risk anyway of getting sick, and doesn’t work at all for people over 65,” Francis Collins, M.D., Ph.D., director of the National Institutes of Health, told the journal.

Some of the experimental vaccines “may turn out to be better for older individuals, and that’ll be a big issue in terms of how we then end up deploying these,” Collins added.

In other COVID-19 news

U.S. coronavirus cases soared by 25% last week; deaths increase

There was a 25% increase in new cases of COVID-19 in the week ended June 21 compared to the previous seven days, reports Reuters. Arizona, Florida and Texas are experiencing record surges in new infections. Meanwhile, COVID-19 hospitalizations are increasing in 17 states, according to ABC News. These include Alaska, Alabama, Arkansas, Arizona, Florida, Georgia, Hawaii, Mississippi, Montana, North Carolina, Oklahoma, Oregon, South Carolina, South Dakota, Texas, Utah and Vermont. 

Severe COVID-19 illness spikes risk for cardiac arrhythmias

Patients admitted to intensive care units with COVID-19 are 10 times more likely to develop a cardiac arrhythmia, a new study has found. “Our findings suggest that non-cardiac causes such as systemic infection, inflammation and illness are likely to contribute more to the occurrence of cardiac arrest and arrhythmias than damaged or infected heart cells due to the viral infection,” wrote researchers from the University of Pennsylvania School of Medicine.