Reporting adverse events following vaccination with Imvamune: Communiqué to healthcare professionals

Date: 2022-10-31

On this page

• Audience
• Key messages
• Issue
• How to report adverse effects following immunization (AEFI)
• About Imvamune use and side-effects

Audience

Health professionals administering the Imvamune vaccine and Health Professionals caring for patients that received the Imvamune vaccine

Key messages

• Healthcare professionals are asked to report any adverse events that occur following Imvamune vaccination to their local or provincial public health authority .
• The Imvamune vaccine is a live, attenuated vaccine that has been approved for protection against smallpox, mpox (monkeypox) and other similar viruses.
• Monitoring the safety of Imvamune vaccine use in the context of the currently ongoing mpox outbreak is important. Reporting suspected adverse events following immunization with Imvamune may help identify new potential safety issues associated with this vaccine to inform vaccination program policy and practice as well as regulatory actions, if necessary.
• By reporting adverse events following immunization (with Imvamune or any other vaccine), healthcare professionals contribute to improved vaccine safety for all Canadians.

Issue

• On July 23, the World Health Organization (WHO) declared the multi-country outbreak of mpox a public health emergency of international concern.
• The Government of Canada supports the WHO determination and continues to work with provinces and territories to gain a better understanding of the evolving outbreak, as well as to implement public health measures to control the outbreak in Canada.
• One of the public measures implemented is vaccination with the Imvamune vaccine, approved in Canada for protection against smallpox, mpox and other similar viruses.
• Monitoring the safety of Imvamune vaccine use in the context of this outbreak is important to inform vaccination program policy and practice. Health care professionals are asked to report any adverse events that occur following Imvamune vaccination to their local or provincial public health authority.

How to report adverse events following immunization (AEFI)

Reporting of adverse events following immunization (AEFI) is mandatory in all provinces and territories (except Newfoundland & Labrador and the Yukon Territory, where there are robust AEFI reporting policies and processes in place). Canada.ca provides contact information for reporting adverse events following immunization.

Health Canada, the Public Health Agency of Canada (PHAC), the provinces and territories work collaboratively to monitor the safety of vaccines and will respond to any safety issues right away, including informing Canadians about any risks that arise.

About Imvamune use and side-effects

Imvamune (Bavarian Nordic) is a Modified Vaccinia Ankara (MVA) vaccine that was initially developed to be used for the prevention of smallpox. Imvamune is a live, attenuated vaccine that has been modified, so that it can no longer cause infection. Imvamune has been authorized by Health Canada for active immunization against smallpox (since 2013), as well as mpox and related orthopoxvirus infection and disease (since 2020) under the provision of the Extraordinary Use New Drug (EUND) regulations in adults 18 years of age and older determined to be at high risk for exposure. The goal of the EUND regulations is to provide Canadians with access to extraordinary use new drugs for which there may be limited human data. EUND are monitored more extensively for safety and effectiveness in the real-world setting (such as the current multi-country outbreak of mpox).

The Product Monograph for Imvamune includes safety and efficacy information about the vaccine, based on non-clinical studies, as well as clinical trials.

The most common local side effects were pain, redness and swelling. The most common systemic side effects were fatigue, headache, muscle aches, chills and nausea. Most of the reported side effects were of mild to moderate intensity and resolved within the first seven days following vaccination.

Rarely, allergic reactions can occur after receiving a vaccine. Symptoms of an allergic reaction include:

• hives (bumps on the skin that are often very itchy)
• swelling of the face, tongue or throat
• difficulty breathing

Some side effects involving the heart were observed during the clinical trials for Imvamune, however no confirmed case of myocarditis, pericarditis, endocarditis or any other type of cardiac inflammatory disease (or related syndromes) was recorded.

Health Canada and the Public Health Agency of Canada are working with provincial and territorial public health partners to monitor and investigate cases of mpox in Canada.