Europe Adds Blood Clot Risk to J&J - Janssen COVID-19 Vaccine

The European Medicines Agency's Pharmacovigilance Risk Assessment Committee (PRAC) announced on April 20, 2021, it concluded that a warning about unusual blood clots with low blood platelets should be added to the product information for COVID-19 Vaccine Janssen. 

The PRAC also concluded that these events should be listed as very rare side effects of the vaccine. And, based on the currently available evidence, specific risk factors have not been confirmed.

The EMA confirmed it had reviewed eight cases of thrombosis in combination with thrombocytopenia in people who received Janssen’s COVID-19 vaccine in the USA. All cases occurred in people below 60 years of age, and most were in women within three weeks of the person being vaccinated.

These very rare types of thrombosis (with thrombocytopenia) included venous thrombosis mostly in unusual sites such as cerebral venous sinus thrombosis and splanchnic vein thrombosis, and arterial thrombosis and a fatal outcome in one case.

Thrombosis in combination with thrombocytopenia requires specialized clinical management. Healthcare professionals should consult applicable guidance and/or consult specialists (e.g., hematologists, specialists in coagulation) to diagnose and treat this condition, says the EMA.

As for the mechanism, it is thought that the vaccine may trigger an immune response leading to a heparin-induced-thrombocytopenia-like disorder. The pathophysiological mechanism has not been established at this time, and it is currently not possible to identify specific risk factors.

Healthcare professionals should be alert to the signs and symptoms of thromboembolism and thrombocytopenia so that they can promptly treat people affected in line with available guidelines.

The COVID-19 Vaccine Janssen was authorized in the EU on March 11, 2021. However, the rollout of the vaccine in the EU was temporarily delayed by the company on April 13, 2021.