On July 18, with six cases confirmed, a relative responded to the nursing home’s email with an emoji of Edvard Munch’s painting “The Scream.” Then came the first death, on July 20. By Tuesday this week, the facility said it had 14 covid-19 cases and two deaths — all among residents who were fully vaccinated in January.

The outbreak — the largest the national chain has seen among vaccinated residents — helped spur Good Samaritan to impose a vaccine mandate on its 16,000 staffers working in 22 states to try to avoid a repeat of the devastating covid-19 surges in spring 2020 and last winter, which contributed to a total of 185,000 pandemic deaths among people in facilities providing long-term care.

As the threat of the delta variant grows, other large nursing home chains also are beginning to adopt vaccine mandates, including the largest for-profit chain, Genesis HealthCare, which is requiring employees to get their first vaccine shot by Aug. 23. Massachusetts said Wednesday that it is imposing a state vaccine mandate on nursing home staffers. These moves are part of a building wave of requirements in health-care settings nationally.