VANCOUVER -- B.C. has recorded its second case of a rare blood clot condition linked to the AstraZeneca vaccine.

Provincial health officer Dr. Bonnie Henry said the latest patient is a man in his 40s who is in stable condition and receiving treatment in the Fraser Health region.

The disorder is known as vaccine-induced immune thrombotic thrombocytopenia, or VITT. During a news conference Thursday, Henry explained “for some reason in some people, the vaccine seems to stimulate an immune response that develops antibodies against our platelets, so this causes a type of clotting that is different from other types of blood clots.”

The provincial health officer has previously said VITT happens after about one in 100,000 doses of AstraZeneca, noting that there is a test to determine if a person has developed the syndrome and there is treatment available.

The announcement also comes just one day after the province announced it would only be using the AstraZeneca vaccine for second doses moving forward.

Henry stressed the move is “not about vaccine safety,” but vaccine supply, adding that “other nations have challenges in getting vaccines, so it is incumbent on us in Canada not to take more than we need.”

She said health officials are also monitoring studies from around the world on mixing and matching of vaccines and will be making that information public when it is available.

“It’s my expectation that people who have received AstraZeneca so far will have a choice, once we know more, about taking Pfizer or Moderna as a second dose.”

Anyone who has been vaccinated should monitor for symptoms between four and 28 days after their shot. Symptoms of VITT include:

  • Severe headache
  • Visual changes
  • Abdominal pain
  • Chest pain
  • Nausea and vomiting
  • Back pain
  • Shortness of breath
  • Swelling and pain in a limb

Anyone with concerns should call 811 or their health-care provider.