According to the Centers for Disease Control and Prevention, the incidence of COVID-19 deaths among those 65 years old and older is about 200 times that of people younger than 35. Because roughly half of all deaths of seniors occur in nursing homes, both in the United States and abroad, improving sanitary conditions seems to be the straightforward solution to reducing deaths among the elderly.
A large risk for seniors in a nursing home stems from their close contact with their caregivers. If caregivers are infected but develop no symptoms, then they may be exposing seniors to high viral loads. And the problem is significant, according to a recent study of the Chilean Association from Worker Safety, an insurer provider.
They tested 2,776 caregivers who work in nursing homes in Santiago, the Chilean capital, with polymerase chain reaction (PCR) tests and found that 50 of them (1.8 percent) who did not show symptoms at the time tested positive. While 1.8 percent may seem like a small percentage, in this case, it translated into 22 out of the 62 surveyed nursing homes (one in three) with at least one infected caregiver. And once the coronavirus enters a nursing home, it has fertile ground to attack susceptible elders. What can be done?
Our research in Chilean nursing homes provides insights to this question. It shows that the risk from asymptomatic caregivers can be significantly reduced by asking staff members to provide daily reports on the health of their close relations and contacts, and the means of transport they used to commute. This information allows the nursing home to assess the individual risks facing each caregiver. Our research also suggests that there is a positive return to frequently testing caregivers for immunoglobulin M antibodies (IgM, those that the body generates after the onset of the infection to combat it) and immunoglobulin G antibodies (IgG, those that the body generates to prevent a new infection). Removing caregivers who tested positive in an immunoglobulin M or an immunoglobulin G antibody test, and then confirming an active infection with a PCR test, can significantly reduce the time an asymptomatic caregiver spends in a nursing home spreading the virus to the elderly and other coworkers.
To quantify how useful antibody tests are, we simulated different protocols with Chilean data. In the average Chilean nursing home, there are 40 seniors and 20 caregivers. Given Chilean infection rates, and assuming that infected individuals that show no symptoms are infectious for 17 days, our simulations suggest that there would be at least one infected asymptomatic caregiver in a given nursing home about 50 percent of the time or, on average, about 0.8 asymptomatic carriers per 100 caregivers. We then simulated testing for antibodies every three days, which reduced the expected frequency of an infected caregiver to about 20 percent of the time and, on average, 0.2 asymptomatic carriers per 100 caregivers.
In addition, the implementation of an information system together with antibody testing provides the benefits of tracking more risky workers and isolating them more quickly if they become infected. Also, early detection contact tracing and further removal of infected caregivers and seniors, thus preventing further contagion.
Unfortunately, the risk of an infected caregiver in a nursing home cannot, as a practical matter, be reduced to zero. The reason has to do with the nature of the antibody tests. Antibodies emerge only some ten days after infection. In addition, the sensitivity of tests (the percentage of infected people who test positive) and their specificity (the percentage of people who are not infected and test negative) varies across tests. It follows that antibody testing cannot be used to diagnose specific patients at the onset of infection; it can only be used to decrease the risk of exponential contagion. People who test positive in an antibody test be confirmed with a PCR test to determine whether they have active infection.
Indeed, the only effective way to bring the risk of asymptomatic caregivers in a nursing home to zero would be to quarantine them for 14 days before they start work and then keep them in the nursing home without leaving the premises.
According to Chilean data, more than 80 percent of COVID-19 deaths and half of beds in intensive care units in hospitals are occupied by people over the age of 60. Protecting those living in nursing homes from contagion would lessen the pressure on the health system and save lives. Therefore, whatever the general strategy for dealing with COVID-19, it should include the frequent testing of caregivers in nursing homes.
Alexander Galetovic is a senior fellow at the Universidad Adolfo Ibáñez in Santiago and a research fellow at the Hoover Institution. Susana Mondschein is professor of the Engineering School at Universidad Adolfo Ibáñez in Santiago.