NACI AstraZeneca Guidance – Suspend Use in Younger Than Age 55

Small increased risk of rare types of blood clots accompanied with thrombocytopenia (low platelets). Called ‘vaccine-induced prothrombotic immune thrombocytopenia’ or VIPIT.

VIPIT is very rare.

Initial estimates from Germany were 4 per million. Subsequent Norwegian estimates are 42 per million.

Per Science Table estimates: occurring in anywhere from 1 in every 125,000 to 1 in 1 million people.

VIPIT does not develop through the same process as usual types of bleeding/clotting problems. Therefore, no evidence that VIPIT is more common in people with personal or family history of blood clots, people with low platelets, those on BCP or pregnant women.

Majority of these these occurred in women. All were in the 20-55 age group and occurred within 4-20 days post-vaccination.

Mechanism of action that is suggested: vaccine triggers antibodies that subsequently induce massive platelet activation, reducing the platelet count and causing thrombosis (clots). This phenomenon mimics heparin-induced thrombocytopenia (HIT) yet it does not require heparin as a trigger.

If you’re under 55 and received the AZ vaccine, watch out for the following symptoms if they occur within 4-20 days post vaccination:

  • severe headache that does not go away
  • seizure – chest pain – new blurry vision
  • difficulty moving part of your body
  • difficulty speaking – shortness of breath
  • severe abdominal pain
  • severe swelling, pain, or colour change of arm/leg

NACI is taking the conservative approach and recommending suspending use in people under age 55 until more information is available. Great example of how swiftly and quickly due diligence is occurring and safety is paramount.