New York City has declared the deadly legionnaires’ disease outbreak in central Harlem over, nearly three weeks since it began.

City health authorities reported on Friday that no new legionnaires’ disease cases have been detected among locals or workers in the vicinity since 9 August. As of that date, a total of 114 cases have been identified, with 90 patients requiring hospitalization. Of these, six are still hospitalized, and the disease has claimed seven lives.

New York City Mayor Eric Adams remarked in a Friday statement, “Today signifies three weeks since a symptomatic individual was identified, suggesting that New Yorkers can begin to relax, as residents and visitors in central Harlem are no longer at heightened risk of contracting legionnaires’ disease – but our work continues.”

He continued, “It’s crucial that we draw lessons from this incident and introduce new measures to enhance our ability to detect and respond to any future outbreaks, as public safety remains our top priority. This incident has been a tragic event for New York City and central Harlem, as we mourn the seven lives lost and hope for the recovery of those still receiving treatment.”

Legionnaires’ disease is a severe type of pneumonia caused by legionella bacteria, which can be transmitted from water systems and devices to individuals. These systems may include showerheads, sink faucets, hot tubs, decorative fountains, extensive plumbing networks, and cooling towers.

An investigation led health authorities to trace the bacteria back to cooling towers located atop the city-managed Harlem Hospital and a nearby construction project under city supervision.

The Centers for Disease Control and Prevention indicates that the most typical means of infection involves inhaling mist that contains legionella. Additionally, the disease can be contracted if a person accidentally ingests contaminated water, which then makes its way into the lungs through a process known as aspiration.

Most healthy people who are exposed to the bacteria do not get sick. Those who are more susceptible to contracting the disease include current or former smokers and people 50 years or older, as well as those with specific health issues.

Symptoms usually develop two to 14 days after exposure to the bacteria and include cough, fever, headaches and muscle aches as well as shortness of breath. Other symptoms include confusion, diarrhea or nausea.

Following the outbreak, all facilities with legionella-positive test results completed full cleaning and disinfection as directed by city officials.

Michelle Morse, New York City’s acting health commissioner, said: “As the city’s doctor, my thoughts are with everyone who has been impacted by the spread of legionella, and our hearts are with the families who lost a loved one … We are working with building owners on next steps to protect the health and safety of Harlem residents and to prevent future clusters.”

Following the outbreak, the Adams administration issued a slew of new proposals that include expanding the health department’s capacity to inspect the city’s cooling towers, requiring building owners to test for legionella at least every 30 days during the cooling tower operating period instead of the current 90-day requirement, expanding the health department’s sampling capacity to conduct proactive sampling of building cooling tower systems, and maintaining contracts to surge capacity when faced with novel issues during future clusters.