Possible human-to-human transmission in Missouri may include healthcare staff

In early September 2024, the Missouri Department of Health reported that a patient with no known exposure to animals that may carry avian influenza was infected with the disease. The patient was only identified as having avian influenza when the patient’s blood specimen was sent to the CDC for testing. This was several days after the patient had been hospitalized.

The CDC later identified several healthcare staff who had come in contact with the patient and had developed mild respiratory symptoms. Further investigation found that 94 hospital workers were exposed to the patient. None of these workers were tested for avian influenza (H5N1) at the time of their illness or exposure. The CDC is now conducting serologic testing (which tests for specific antibodies) to determine if any of these workers were infected with influenza A(H5N1). Test results are still pending.

What went wrong?

1. A patient with an unknown respiratory condition was admitted to the hospital. No respiratory transmission controls were put in place. Only after several days was the patient put on “droplet controls,” requiring the use of surgical masks. Surgical masks do not prevent respiratory transmission, as airborne spread includes both large droplets and small airborne particulates. Only a respirator, such as an N95, elastomeric respirator or PAPR will prevent transmission.
2. The CDC requires that respirators be used to protect healthcare staff when there is a risk of exposure to “novel pathogens.” Without proper testing the hospital assumed this was not a novel pathogen. Even when CDC testing confirmed that the patient was infected with avian influenza, a novel pathogen, the hospital did not require the use of respirators.
3. After it was determined that the patient was infected with avian influenza, the hospital did not survey exposed staff to determine if any of them had become ill after close contact with the patient. This information became available several weeks later. Further investigation by the CDC uncovered additional symptomatic staff and a large number of exposed hospital staff. Clearly, the hospital made no effort to limit close contact with the patient.

Protecting Healthcare Staff

At this time, it is not known if any of the exposed healthcare staff were infected with H5N1. However, if testing does determine that any of them were infected, it will be the first known case of human-to-human avian influenza transmission in the United States (along with the source patient).

At this time, it is not yet known if the avian influenza A (H5N1) virus has mutated in a way that allows efficient human-to-human transmission. However, all healthcare facilities should follow the precautionary principle by instituting airborne transmission controls for any suspect case. These controls should include:

• Rapid identification and isolation of potentially infected patients.
• Use of airborne infection isolation rooms (AIIRs) with negative pressure.
• Proper PPE including respirators, gowns and gloves.

As frontline healthcare workers, nurses are at high risk of exposure to infectious diseases, including novel pathogens that result in hospitalization. NYSNA’s health and safety representatives are committed to educating and advocating for our members to improve the health and safety of nurses and our patients. NYSNA will provide updates on this situation as they become available.