Hospital staff infected with coronavirus in air released from ventilator

A doctor and two nurses at Sourasky Medical Center may have been infected with the coronavirus by the aerosol coming from a ventilator being used on a patient, according to an initial investigation of the incident, Israel Hayom reported.

Eight ventilators were being used in tandem at the time.

After the investigation, the hospital decided to place a limit of six patients on Vapotherm ventilators in each ward. Vapotherm ventilators are devices that use a nasal cannula with high pressure air flow instead of a mask or invasive tube. The ventilators will also be placed under air vents in order to reduce the amount of aerosol in the air.

The infection in coronavirus wards of medical staff, who are equipped with maximal personal protective equipment (PPE), is considered a rare occurrence. In the first wave, only a few isolated cases of medical staff who were infected with the virus were those working in coronavirus wards, according to Israel Hayom, while most who were infected were infected in other wards, by family members or at social events.

"We have almost no infections within the coronavirus wards; this is an uncommon occurrence," Dr. Yael Paran, an expert on infectious diseases and head of Sourasky's Traveler's Clinic, told the newspaper. "These are departments with an air intake system and negative pressure, departments that are entered into with 'space suits' in a very controlled manner and with observation on protection. Therefore, we investigated in order to understand what happened this time."

She added that, "When we investigated, we found that these were employees who were very strict about the procedures even outside of work and that none of their family members became infected. This is a sequence of incidents that happened during the last week and it lit a red light for us. Infection in the coronavirus ward is something we are very afraid of."

The hospital checked the integrity of the ventilators and the staff's attention to regulations without finding anything wrong. After checking the schedule, they arrived at the conclusion that a week before the infections, the coronavirus ward was at peak capacity, with eight patients on ventilators at once.

Paran hypothesized that "when a certain threshold of aerosol formation is exceeded, it exceeds the flow threshold of the ventilation and protection systems," according to Israel Hayom. There is some literature that supports this hypothesis as well, she said. A hospital in northern Israel also reported a similar incident.

The US Centers for Disease Control and Prevention (CDC) in an updated guidance last week said COVID-19 can spread through airborne transmission, saying some people could get infected by exposure to the novel coronavirus in small droplets and particles or aerosols that can linger in the air for minutes to hours.

Aerosols lingering in the air could be a major source of COVID-19 transmission, a group of US scientists warned in an unrelated open letter published in the medical journal Science last week.

Researchers around the world have reported findings showing evidence that the virus may be airborne since as early as April, although it remains unclear how infectious airborne droplets are.