Older adults may bear most of the burden if coronavirus spreads

Those older than 75 are often more susceptible to viral illnesses, experts say.

Those older than 75 are generally more susceptible to both bacterial and viral illnesses. The older adult is particularly vulnerable to viruses, as it takes a strong immune system to fight viral illness in which antibiotics are useless. As we age, the thymus and bone marrow produce less of the vital B and T cells, which are key players in the immune system.

Data from China indicates that the oldest of those affected were more likely to be hospitalized during the recent outbreak, and the oldest of the old were less likely to survive the severe respiratory illness that results from the infection.

According to the epidemiological reports from more than 72,000 Chinese patients, the overall case fatality rate was estimated to be 2.3%, while those between age 70 and 79 had a case fatality rate of 8%. For those over 80, almost 15% did not survive. (These figures are from the start of the outbreak through Feb. 11.)

The latest cluster of coronavirus cases in Italy is in an area of Europe that's home to the highest number of seniors above the age of 65. From the 322 or so confirmed cases in Italy, all 11 fatalities were among older adults. The reported four deaths on Feb. 25 were adults between 76 and 91 years old. Eighteen more deaths have been reported in Italy in the last 24 hours, with additional victims over 80.

Some nursing home directors in Italian cities hard hit by the viral disease are enacting what is called a “reverse quarantine,” in which nursing homes are restricting all visitors, including family members in some cases.

Nursing homes not only are areas where older, often frailer adults are clustered, but they're also known to be prone to small viral outbreaks. Viruses causing respiratory illnesses that have been isolated in nursing homes include respiratory syncytial virus (RSV), influenza and rhinovirus. More recently, a study published last year in the Centers for Disease Control's Emerging Infectious Diseases highlighted a metapneumovirus outbreak in a nursing home in New Mexico.

Viruses like this are as contagious as the coronavirus, but the coronavirus is more damaging to the lungs. Researchers noted the difficulties in controlling the spread of disease, especially with residents who may be suffering from dementia. Additional challenges were staffing shortages and a lack of infection control supplies.

Dr. David A. Nace, president-elect of AMDA Post-Acute and Long-Term Care Medicine, told ABC News that the CDC is working on specific guidelines for nursing home and long-term care facilities. The challenge, says Nace, is that a nursing home is not like an acute care facility, such as a hospital -- but at the same time it's not entirely a home either.

According to Nace, at this time visitors and health care workers should use common sense and not visit nursing homes or long-term care facilities if they are having a fever or respiratory symptoms. There is no need for restricting visitors otherwise, he added, and masks have no use at this time.

Nursing homes are following the CDC's Feb. 28 guidelines, which recommend that health care workers practice "frequent hand hygiene;" place an individual suspected of being infected in "a single room with a closed door pending consultation with their local health department;" and stay home and seek health care if they're ill.

Imran Ali is a geriatric physician working with ABC News’s Medical Unit.