The novel coronavirus tore through long-term-care facilities for the elderly in spring. It continued into summer months, leaving hundreds of thousands of people dead around the world.

Now, as autumn heads toward winter and the Northern Hemisphere prepares for a cold-weather surge in coronavirus cases, experts who focus on long-term care are desperate to avert the next chapter in the disaster.

There are few easy lessons. In many countries, the trend is hard to escape: The larger the coronavirus outbreak in an area, the more deaths elder-care facilities there can expect to see, according to the results of an ongoing transnational research project, which published new data this week.

Across 26 countries, elder-care home residents have accounted for an average of 47 percent of recorded coronavirus deaths, according to data collected by the International Long-Term Care Policy Network, a global collaboration between academics and policymakers.

In some nations, including the United States, the data suggests that about 1 in 20 elder-care residents have already died of covid-19 during the pandemic. Facilities continue to confirm new infections. In Wyoming, the number reporting new cases nearly doubled over the past week, the Casper Star-Tribune reported.

“The idea that you could somehow protect the people living in care homes from whatever is going on outside hasn’t worked,” said Adelina Comas-Herrera, a researcher at the London School of Economics and coordinator for the network.

Covid-19 cases are again on the rise in much of the world. Although deaths have not yet risen to the same extent, some experts worry that elder-care facilities remain vulnerable.

In Italy, where Milan’s historic Pio Albergo Trivulzio nursing home became a symbol of the risks of covid-19 for the elderly after 300 residents died this spring, homes are “unprepared for the probable second wave” likely to arrive within weeks, said Marco Trabucchi, president of the Italian Psychogeriatric Association.

Researchers have had to ask hard questions about what made these facilities so vulnerable, leading to changes that may linger long after the pandemic.

“We have to think outside the box,” said Sunil Parikh, an assistant professor at Yale University who has advised Connecticut on care homes. “And maybe a little outside our comfort zone.”

Difficult data

Long-term care facilities, which are not widespread in every country, tend to concentrate vulnerable populations in conditions suited to the spread of the virus.

In Canada, where more than 9,300 people had died of covid-19 by the start of October, roughly 80 percent of recorded deaths occurred among long-term care residents, the researchers found — the highest proportion out of more than two dozen countries studied.

In the United States, roughly 41 percent of covid-19 deaths were recorded among nursing-home residents. As of last month, at least 82,105 resident had died, the highest figure among the nations studied. In Spain, they caused around 63 percent of almost 33,000 deaths.

Comparisons between countries pose challenges, including differences in societal practices around care for the elderly and, most of all, divergences in data availability and standards, Comas-Herrera cautioned.

Italy, one of the worst-hit countries in Europe, collects little data from long-term care homes despite its aging population. Trabucchi said that Italy’s national and regional governments had not given “realistic indications” of the problem.

These gulfs can make lessons difficult to apply internationally. The only true metric for understanding the impact of covid-19 on elder-care homes is to look at the total number of deaths among residents and compare the change over previous years, but that data is rarely published, Comas-Herrera said.

“I think more countries have it but do not publish it,” she said.

What went wrong

In Sweden, the government’s strategy to avoid a strict shutdown was based partly on allowing the virus to spread among those at low risk of serious complications so that those at high risk could be better protected.

By early spring, that aspect of the approach had failed. This week’s report suggests 46 percent of the more than 5,800 covid-19 deaths in Sweden took place in long-term care homes for the elderly, roughly in line with the average in other nations.

“We must admit that the part that deals with elderly care … has not worked,” Prime Minister Stefan Löfven told the Aftonbladet newspaper in June. A decision to ban visitors to nursing homes, first instituted March 30, was repeatedly extended until visits resumed in October amid controversy.

Even when strict measures have been implemented, there are no guarantees. In Hong Kong, where a large proportion of the elderly population live in care homes, by mid-January, visitation hours were cut and residents were made to eat meals alone in their rooms.

The moves appear to have been a success in the short term. But as restrictions were relaxed in May, cases in the city surged again. They soon found their way into the care home system. At least 30 fatalities have been linked to Hong Kong’s care home network, roughly a quarter of all covid-19 deaths in the city.

Terry Lum, a professor at the University Hong Kong, said that the big worry was that covid-19 could slip into facilities through seemingly healthy staff members. “We worry about infected staff who do not have symptoms,” he wrote in an email this summer.

Signs of success

It’s not all gloom. Despite their aging populations, South Korea and Japan have avoided large-scale deaths in care homes. China, where the coronavirus first emerged, has not reported a large number of deaths in elder-care homes.

A number of nations that initially saw large-scale deaths in care homes have performed better as their outbreaks went on. At least some current hot spots in the U.S. Southwest have so far avoided the scale of care home deaths that the Northeast saw in spring, alongside a broader decline in mortality rates.

But it can be hard to isolate tactics that work. In some facilities in Spain and Britain, having staff live on site and submit to frequent testing appears to have helped keep the virus out. In the United States, rapid response teams that isolate patients and take them to hospitals have been helpful in limiting the virus’s spread.

Even proven tactics, though, can exact a cost in quality of life. Without visits from families and friends, many residents can suffer emotionally. “We are well aware of the mental problems facing the patients in nursing homes, as a consequence of their loneliness,” said Trabucchi, who added he saw no alternative.

Having staff live on site would be difficult in many nations, where private agency staffers often work at multiple facilities. Even the expense of testing staff members regularly could affect the margins of an industry often based on cheap, easy labor.

Many tactics have a significant financial cost. In South Korea or Hong Kong, where the state is heavily involved in long-term care facilities, the government may cover them. But in nations where private ownership of elder-care homes is common, such as Britain and the United States, companies must keep expenses down.

“They have to provide a lot more staff, they have to provide a lot more equipment, they have to have more space,” said Shereen Hussein, a professor of care and health policy at the University of Kent. “This means profit margins are reduced.”

Elder-care facilities may see significant changes — and not just in the short term. The International Long-Term Care Policy Network predicts higher costs and lower demand for elder-care services may not be a blip but could last for “many years to come.”

This report has been updated.