VANCOUVER -- The president of the B.C. Nurses' Union says she's very concerned about a COVID-19 outbreak at Abbotsford Regional Hospital that has sickened six health-care workers, including four nurses.

Two patients have also tested positive for COVID-19, according to Fraser Health. The outbreak has been centred around the intensive care unit at the hospital. The four nurses who have tested positive worked in the ICU, according Christine Sorensen, president of the B.C. Nurses’ Union.

A number of other hospital staff are also being tested, Sorensen said.

"We are investigating with Fraser Health and Worksafe(BC) why such a large number of health-care workers have been infected at this site — this is very concerning for us," said Sorensen.

Sorrensen said the union has been hearing concerns about difficulties in accessing personal protective equipment from nurses all over the province, including at Abbotsford Regional Hospital.

But Fraser Health and B.C.'s provincial health officer, Dr. Bonnie Henry, have strongly denied that there was any PPE shortage at the hospital.

In a statement emailed to CTV News, Jacqueline Blackwell, director of public affairs for Fraser Health, said there is “no evidence of any PPE break during patient care that has led to this outbreak.”

Henry echoed that comment.

"There has been no shortage of PPE with the health-care workers in those facilities to access what they need to safely care for people with COVID-19 in the ICU," Henry said during a press conference Saturday.

"That is not an issue."

Personal protective equipment, also known as PPE, includes items like masks, gloves, protective gowns and face shields, and is vital for anyone working in close contact with people who may be carrying the virus.

But the global nature of the COVID-19 pandemic means that the items have been in short supply around the world.

"We will be following up closely with the health authority and WorksafeBC in regards to what personal protective equipment was available and how readily it was available," Sorensen said.

In response to comments denying any shortage of PPE from Fraser Health and Henry, Sorensen said the union stands by its statements.

“If Dr. Bonnie Henry and Fraser Health say PPE is adequate, then we question the administrative and engineering controls put in place to protect staff," Sorensen wrote in an email to CTV News Vancouver.

"The priority for everyone should be the health and safety of staff and the patients they care for and ensuring all health care workers do not get infected with COVID-19.”

Sorensen said she's also concerned that the number of staff who came down with the illness will affect staffing levels at the hospital. The nurses who contracted COVID-19 worked in critical care, an area where there is a "desperate need" for nurses right now, Sorensen said.

Blackwell said all staff were wearing PPE and “taking all appropriate precautions while in care areas.” Abbotsford Regional Hospital does not have a shortage of PPE, according to Fraser Health.

“Preliminary results of our investigation show that vigilance is required in non-patient care areas,” Blackwell said. “Enhanced strategies have been implemented to reduce risks in these areas.”

Henry said the outbreak at Abbotsford Regional Hospital shows how "pernicious" the virus is.

She added that measures B.C. has undertaken to make sure hospitals are not overwhelmed by COVID-19 cases have worked to keep health-care workers safe.

Those measures have meant that health-care workers have the time to carefully put on and take off their protective gear and make sure they're not inadvertently infecting themselves with contaminated equipment, Henry said.

With files from CTV News Vancouver's Alissa Thibault.