A nursing home reports low influenza vaccine uptake among staff and residents followed by an outbreak. Which immediate actions best reduce further transmission and protect unvaccinated and immunocompromised residents?

Only give boosters to residents who previously declined vaccination while continuing normal staffing and visitation policies because incremental vaccination of residents alone will immediately restore herd immunity within 24 hours.

Implement urgent targeted vaccination of staff and residents, use antiviral prophylaxis for exposed high-risk residents, restrict nonessential visitors, and reinforce mask use and cohorting until transmission is controlled.

Do nothing beyond informing families because outbreaks in congregate settings always resolve spontaneously without interventions and because additional measures would infringe on residents' autonomy.

Close the facility permanently and discharge all residents to the community immediately because institutional settings cannot be salvaged once any outbreak begins, which is the only ethical option.