By NewsDesk  @infectiousdiseasenews

The Canadian National Advisory Committee on Immunization (NACI) Monday recommended that the AstraZeneca COVID-19 vaccine should not be used in adults under 55 years of age at this time while the safety signal of Vaccine-Induced Prothrombotic Immune Thrombocytopenia (VIPIT) following vaccination with AstraZeneca COVID-19 vaccine is investigated further.

Image by Alexandra_Koch from Pixabay

The recommendation is based on rare cases of serious blood clots, including cerebral venous sinus thrombosis (CVST), associated with thrombocytopenia that have been recently reported in Europe following post-licensure use of AstraZeneca COVID-19 vaccine.

Cases identified have mostly occurred between 4 and 16 days after receipt of vaccine. This adverse event is being referred to as Vaccine-Induced Prothrombotic Immune Thrombocytopenia (VIPIT). Women have been more affected than men.

The rate of this adverse event is still to be confirmed. Based on information from the European Medicines Agency on March 18, 2021 it was originally estimated at approximately 1 per 1,000,000 people vaccinated with the AstraZeneca vaccine, however a higher rate of 1 per 100,000 was reported by the Paul-Ehrlich Institut in Germany.

NACI says following population-based analyses of VIPIT assessing risk of COVID-19 disease by age, and considering that alternate products are available (i.e., mRNA vaccines), from what is known at this time, there is substantial uncertainty about the benefit of providing AstraZeneca COVID-19 vaccine to adults under 55 years of age given that the potential risks associated with VIPIT, particularly at the lower estimated rates. As a precautionary measure, while Health Canada carries out an updated benefit/risk analysis based on emerging data, NACI recommends that the vaccine not be offered to adults under the age of 55. Adults 55 years of age and older may still be offered the AstraZeneca vaccine with informed consent, given the increased risk of hospitalization and death due to COVID-19 disease in this population and since VIPIT appears to be a rarer event in that age group.

Canada is expected to receive sufficient mRNA COVID-19 vaccines to fully vaccinate the population with two doses of mRNA vaccine before fall 2021.