A hospital in California is facing a coronavirus outbreak, with nearly four dozen staff testing positive for the virus, that might be owing to an inflatable, air-powered costume worn on Christmas only to cheer up patients.

At Kaiser Permanente San Jose Medical Center, 43 employees in the emergency department tested positive for the virus between December 27 and January 1, according to CNN reports. 

Irene Chavez, senior vice president and area manager of the hospital, said in a statement that the medical centre is investigating whether the “air-powered costume” may have played a role in the spread.

“A staff member did appear briefly in the emergency department on December 25th wearing an air-powered costume. Any exposure, if it occurred, 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,” Chavez said, reported CNN.

Meanwhile, Chavez added that the air-powered costumes will no longer be allowed at the facility.

“If anything, this should serve as a very real reminder that the virus is widespread, and often without symptoms, and we must all be vigilant,” she said in the statement.

The emergency department employees at the medical centre who were given a COVID-19 vaccine only had their first inoculation days prior to Christmas Day and definitely would not have been immune by the time of the incident.

None would have had their second booster shot by Christmas Day.

“During this period, even as vaccine is beginning to be provided in our communities, it is crucial that everyone continue to protect themselves and each other by continuing to use masks, hand washing, avoid gatherings, and practice social distancing,” the hospital said, NBC News reported.

In California, hospitals are already treating an unprecedented number of coronavirus patients, amid a new surge of the virus.

California has recorded 2,345,909 confirmed coronavirus cases, with more than 26,000 deaths, according to numbers released by the state’s public health department on Saturday.  

Meanwhile, at least 123,000 people nationwide were in the hospital with coronavirus on Sunday, marking more than a month that the number of hospitalizations has exceeded 100,000, according to the Covid Tracking Project.

Cases have skyrocketed after the Thanksgiving holiday, and impacts from Christmas and New Year’s celebrations are still unfolding.

As of Sunday, more than 20.4 million people have been infected with the virus in the US and at least 350,000 people have died, according to data from Johns Hopkins University.