One San Jose Kaiser Permanente employee is dead and 44 have tested positive for COVID in a post-Christmas outbreak possibly tied to an inflatable Christmas tree costume.

All the infected staff were working in the hospital’s emergency room on Christmas Day. One staff member, a registration clerk in the department, has since died of COVID complications.

The hospital reportedly is looking into whether the fan-powered inflatable Christmas tree costume, which a staff member briefly wore in the emergency room that day, is to blame for the exposure – but at least one employee has raised questions about that explanation.

If the costume was to blame, it “would have been completely innocent, and quite accidental, as the individual had no COVID symptoms and only sought to lift the spirits of those around them during what is a very stressful time,” a Kaiser spokesperson told the San Francisco Chronicle.

However, an anonymous employee alleged to NBC Bay Area that hospital protocols could be to blame instead, and staff members told the outlet that workers haven’t been regularly tested.

“They were doing respiratory treatments inside a room that they’re not supposed to,” the outlet cited the unnamed employee as saying. The source also asserted that Kaiser had failed to complete a deep cleaning of the department.

The hospital responded to the claims with a statement that it is following CDC protocols and that deep cleaning is ongoing, NBC Bay Area reports.

The story has sparked sympathy, concern, and consternation, as observers have alternately pointed fingers and encouraged compassion for healthcare workers stretched to the breaking point.

“Hoping anyone who's gloating over this and feeling superior has been working around the clock for the last 10 months of the pandemic to help others and also tried to do something nice that backfired,” posted one Twitter user in response to a photo of the costume in question.

Amidst the comments and commentary, one question rose to the top: Why weren’t the emergency room workers protected by their personal protective equipment (PPE)?

The Chronicle spoke with outside experts who confirmed that airborne exposure is a likely culprit for the outbreak, whether or not the costume itself was instrumental – and that an inflatable costume could certainly increase airborne transmission.

“There’s no other way [so many] people caught it except for through the air,” U.C. San Diego atmospheric chemistry professor Kimberly Prather told the Chronicle, explaining that the coronavirus can “spread like cigarette smoke.”

“This is just further evidence that the air is important,” Prather told the paper. “I’d be less focused on the poor person who had air in their costume.”

The paper also spoke with UCSF medicine professor and infectious disease expert Dr. Peter Chin-Hong, who said it was “certainly plausible” that the costume could have increased airborne exposure, pointing to a much-reported study out of South Korea that showed airflow in a restaurant spreading infection.

“It’s like a fan that’s kind of multidirectional and random,” Chin-Hong said of such a costume.

Kaiser has said it will no longer allow inflatable costumes at any of its locations.

Whatever the cause of the outbreak, Kaiser told news outlets that the hospital remains open and safe for patient care.