Summary safety review - Janssen COVID-19 Vaccine - Assessing the Potential Risk of Thrombosis in combination with Thrombocytopenia
Review decision
A Summary Safety Review complements other safety related information to help Canadians make informed decisions about their use of health products. Each summary outlines what was assessed in Health Canada’s review, what was found and what action was taken by Health Canada, if any.
Issued: 2021-05-04
Product
Janssen COVID-19 Vaccine
Potential Safety Issue
Reports of very rare cases of blood clots (thrombosis) in combination with low blood platelets (thrombocytopenia)
Overview
Use in Canada
- Janssen COVID-19 Vaccine is authorized for sale in Canada for active immunization for the prevention of COVID-19 caused by SARS-CoV-2 virus in individuals 18 years of age and older. This authorization includes conditions requiring the manufacturer to provide additional information to Health Canada on the vaccine's effectiveness, along with active safety monitoring.
- Janssen COVID-19 Vaccine has been authorized in Canada since March 2021. The vaccine is expected to be distributed and administered in Canada in early May 2021.
- Janssen COVID-19 Vaccine is available as a suspension for injection into the muscle, in multiple dose vials.
Safety Review Findings
- Health Canada reviewed the available information from international databases, the manufacturer and international regulators.
- At the time of the review, Health Canada took into consideration all currently available information including 8 reports of blood clots associated with low platelets, 1 of which had a fatal outcome, from the US. Of the 8 cases, 2 were found to be probably linked and 6 were possibly linked to the use of Janssen COVID-19 Vaccine.
- All cases occurred within 3 weeks following vaccination and mostly in women under 50 years of age. These cases are similar to those that were reported after administration of the AstraZeneca COVID-19 Vaccine and COVISHIELD2.
- A link between blood clots with low platelets and Janssen COVID-19 Vaccine is considered possible. The potential risk of blood clots and low platelets is very rare. Health Canada's findings are in line with the conclusions of international regulators.
- Based on the available information, no specific risk factors, such as age or gender, for these events have been identified.
- A potential mechanism for the combination of blood clots with low platelets is the triggering of an immune response by the vaccine, leading to a condition similar to heparin-induced thrombocytopenia seen sometimes in patients treated with the blood thinner medication heparin.
Conclusions and actions
- Health Canada's review of the available information concluded that a link between the use of Janssen COVID-19 Vaccine and the risk of blood clots with low platelets is possible. The risk of these events is very rare.
- The overall benefits of Janssen COVID-19 Vaccine in preventing COVID-19 outweigh the risk of very rare events of blood clots in combination with low platelets.
- Health Canada's review of available information did not identify specific risk factors, such as age or gender, for these very rare events. Therefore, Health Canada is not restricting the use of the vaccine for certain populations or age groups. The risk of severe disease associated with COVID-19 illness varies with age and continues to change as the nature of the pandemic changes.
- Health Canada has published information for vaccine recipients on signs and symptoms to monitor after vaccine administration and when to seek medical attention. Health Canada has also provided healthcare professionals with information to identify and promptly treat this condition according to current evidence and clinical guidelines.
- Health Canada worked with the manufacturer of Janssen COVID-19 Vaccine to update the CPM with this safety information. Health Canada also requested that the manufacturer update the risk management plan for the Janssen COVID-19 Vaccine to reflect the latest information about this safety issue, and to include plans for studies that will address remaining knowledge gaps.
- Health Canada will continue to monitor the safety of Janssen COVID-19 Vaccine, as it does for all health products on the Canadian market. Health Canada will also continue to work closely with international regulators, the manufacturers, the Public Health Agency of Canada, as well as the Provincial and Territorial public health authorities, to review information as it becomes available on these very rare events, and will make further updates to the CPM or take other actions as needed.
Additional information
The analysis that contributed to this safety review included information provided by the manufacturer, consultations with scientific experts, and what is known about the use of Janssen COVID-19 Vaccine internationally.
On April 23, 2021, the US lifted the pause on Janssen COVID-19 Vaccine and use of the vaccine resumed. As of this date, a total of 15 cases of blood clots with low platelets, out of 7.9 million doses administered, have been reported to the US Food and Drug Administration.
The COVID-19 vaccines and treatments portal provides information for consumers, healthcare professionals and researchers on vaccines and treatments authorized for COVID-19, as well as those currently under review.
For additional information, contact the Marketed Health Products Directorate.