A new US study suggested nursing homes can better control influenza outbreaks by responding early and broadly with antivirals. Initiating oseltamivir chemoprophylaxis in at least 70% of residents within 48 hours of outbreak onset reduced hospital admissions — could this be a feasible strategy for nursing facilities in Germany?

In Germany, nursing homes have relied primarily on isolating cases, strict hygiene measures, and preventive influenza vaccination to control outbreaks. “The focus should remain on vaccination — you should achieve high vaccination rates among residents and also among staff,” said Markus Gosch, MD, past president of the German Society for Geriatrics and chief physician of the Department of Internal Medicine, with a focus on geriatrics, at Klinikum Nürnberg Hospital, Nuremberg, Germany.

No Uniform Recommendations

There are also differences in recommendations: in the US, both the CDC and the Infectious Diseases Society of America (IDSA) advise rapid antiviral chemoprophylaxis for exposed residents — regardless of vaccination status and typically with oral oseltamivir.

Germany does not have nationwide, equally prescriptive guidance calling for rapid, broad chemoprophylaxis regardless of vaccination status. That said, antiviral chemoprophylaxis is an accepted outbreak measure — for example, a checklist from the Robert Koch Institute, Berlin, Germany (Germany’s public health agency), explicitly lists it as an option for asymptomatic residents and staff.

Joe B. B. Silva, PhD, and colleagues at Brown University School of Public Health, Providence, Rhode Island, caution that the CDC’s and IDSA’s strong guidance is based on limited, low‑quality evidence. “For practice, high‑quality data on the required coverage and the optimal timing of treatment are particularly necessary,” the team wrote in JAMA Internal Medicine.

Observational Study

Because randomized trials during influenza outbreaks in nursing homes are rarely feasible for practical and ethical reasons, Silva and colleagues used a target trial emulation (a method that uses observational data to emulate a randomized trial).

Their analysis was based on electronic health data from nursing homes run by 12 US organizations, from which they determined whether and to what extent oseltamivir was prescribed after an outbreak was detected.

70% Coverage, Within 2 Days

They compared an intensive chemoprophylaxis strategy — defined as giving oseltamivir to at least 70% of eligible residents within 2 days — with a non-intensive strategy, in which fewer than 70% of nursing home residents were treated.

In total, Silva and his team analyzed 404 influenza outbreaks in 318 nursing homes and 29,683 exposed residents (35,086 observations, allowing for multiple counts). Residents had a median age of 78, and 76% had been vaccinated against influenza.

No Difference in Mortality, but Fewer Hospitalizations

After 14 days, there was no difference in overall mortality: in homes with less intensive chemoprophylaxis, 1.65% of residents died compared with 1.59% in homes with intensive prophylaxis. The absolute difference of -0.06 percentage points was not significant.

Hospitalizations told a different story: At 14 days, the intensive strategy was associated with a significantly lower hospitalization risk — 3.58% vs 4.54% under the non‑intensive strategy (risk difference, -0.96 percentage points). At 30 days, the difference remained in the same direction, but the estimate was less precise, reflecting greater uncertainty.

Sensitivity analyses supported the finding: An effect on hospitalizations was consistently seen at thresholds of ≥ 60% and ≥ 80% of treated residents within 2 days, but not when prophylaxis was started only after 7 days.

For the authors, this suggests that speed and broad implementation may be decisive. “Clinicians, facility leaders, and nursing staff should consider a rapid, broad chemoprophylaxis — including for residents in unaffected units — as a strategy to curb future influenza outbreaks,” they wrote.

Organizationally Difficult

In Germany, such a strategy would likely be difficult to implement, Gosch said. The study provides important evidence of the prophylaxis’ effectiveness and a strong argument for its use, he added, but practical conditions differ from those in the US.

“Residents in German nursing homes are often cared for by different general practitioners. You would have to involve all attending physicians and jointly decide whether to start prophylactic treatment — under the current structures, I consider it extremely difficult to implement this within 2 days,” Gosch said.

Whether chemoprophylaxis is administered in the event of an outbreak is therefore generally an individual decision made by the treating physician in consultation with the resident. Vaccination coverage remains the primary goal.

This story was translated from Medscape's German edition.