Hamilton lab finds treatment for potentially deadly blood-clotting condition
A treatment for vaccine-related blood clots has been found by McMaster University researchers just as Ontarians have to make a decision about whether to get a second dose of the AstraZeneca COVID vaccine.
AstraZeneca has been linked with a rare but potentially deadly condition called vaccine induced thrombotic thrombocytopenia (VITT). The risk is estimated to be one in 600,000 for a second dose based on data out of the United Kingdom.
If you were a patient with VITT, I'd be telling you we know of a treatment approach," said Ishac Nazy, scientific director of the McMaster Platelet Immunology Laboratory (MPIL). We can diagnose it accurately with our tests, treat it and we know exactly how the treatment works."
The treatment is a combination of anticlotting drugs with high doses of intravenous immunoglobulin.
It's effectiveness was described in a report published Wednesday in the New England Journal of Medicine that described three Canadian patients who got VITT after receiving the AstraZeneca vaccine. Two developed blood clots in their legs and the third had clots blocking arteries and veins in their brain.
We now understand the mechanism that leads to platelet activation and clotting," said Nazy.
Platelets in the blood clump together and form clots after being activated when antibodies attack a blood protein called platelet factor 4 (PF4).
Lab tests on patient blood samples after the treatment show it shut down platelet activation and stopped clot formation, found the study funded by the Canadian Institutes for Health Research.
The patients in the study were older - a 72-year-old woman who started having limb pain seven days after vaccination, a 63-year-old man who got cramping in his leg 18 days after getting the shot and a 69-year-old man who started having headaches, confusion and progressive left-sided weakness 12 days after getting AstraZeneca.
However, Nazy said VITT is a rare disorder, regardless of people's age.
The lab's scientists - including former dean of McMaster's Michael G. DeGroote School of Medicine. Dr. John Kelton - built on their previous investigations of heparin-induced thrombocytopenia (HIT) to create a VITT test and the treatment.
Joanna Frketich is a Hamilton-based reporter covering health for The Spectator. Reach her via email: jfrketich@thespec.com