VANCOUVER -- B.C. health officials announced 587 more cases of COVID-19 and five related deaths during a live briefing on the province's response to the pandemic Thursday afternoon.

The latest update brings B.C.'s active caseload to 5,691, down slightly from Wednesday's total. It also brought B.C.'s rolling seven-day average of new cases below 600 for the first time since March 21. The average currently stands at 598.

There are currently 413 people fighting the coronavirus in B.C. hospitals, and 141 of them are in intensive care units.

B.C. has now seen 137,810 cases of COVID-19 and 1,632 deaths from the disease since the pandemic began.

In addition to the latest numbers, provincial health officer Dr. Bonnie Henry shared provincial modelling data during Thursday's briefing.

Henry's presentation Thursday focused on the rate of infection B.C. has been seeing among people who have received at least one dose of a COVID-19 vaccine.

Nearly all of the province's recent cases - 98 per cent, according to Henry - have been found in people who either haven't been vaccinated or who had received a first dose of vaccine less than 21 days before the onset of their symptoms.

The provincial health officer also announced that B.C. had recorded a second case of rare blood clots associated with the AstraZeneca vaccine.

Henry said the latest B.C. resident to suffer vaccine-induced immune thrombotic thrombocytopenia, also known as VITT, is a man in his 40s who resides in the Fraser Health region. He is in stable condition and is receiving treatment, she said.

"As we know, this is a rare, but very serious condition, and we are following it carefully," Henry said. "Recognizing the symptoms and getting treatment early is important."

B.C. detected its first case of VITT earlier this month

On Wednesday, the province surpassed the 50 per cent mark in terms of first doses of COVID-19 vaccines administered to the eligible adult population.

B.C. has administered a total of 2,335,513 doses of the Pfizer, Moderna and AstraZeneca vaccines, Henry said Thursday. The vast majority of those are first doses, with just 119,691 second doses administered so far.

"Our immunization program is moving quickly as more and more vaccines are available and the ages for those eligible are coming down," Henry said. "We anticipate that all adults will be eligible very soon."

The province is also working on incorporating 12-to-17-year-olds into its vaccination plan, the provincial health officer said, promising more information on the topic next week.

While the province has been trending in the right direction in recent weeks, Henry said there is still "a lot" of COVID-19 circulating in B.C.

"We won't get to the bottom of our infection curve until we get to a much higher immunization rate," she said.

While the success of vaccination in B.C.'s long-term care homes, in First Nations and in Prince Rupert should give B.C. residents hope for the post-COVID future, Henry said it will be some time before the province can get back to normal.

Physical distancing, masks and other COVID-19 restrictions will remain in place in the meantime, she said.

"We will not be seeing any changes to the measures we have in place right now until after the May long weekend," Henry said. "And even then, it's not going to be flicking the switch, it's going to be gradually and slowly increasing the light."