Measuring Vaccine Effectiveness

Vaccine effectiveness measures how well a vaccine prevents infection in real-world settings.  Evaluating vaccine effectiveness is critical to understand the risks and benefits of vaccination programs.  Vaccine effectiveness varies between vaccines, patient populations, circulating viral strains and it can even be affected by how vaccines are transported and stored.  As such, vaccine effectiveness can vary from year to year because viruses like influenza and SARS-CoV-2 (COVID-19) change quickly, leading to the emergence of new strains.  To ensures vaccines remain effective, some vaccines require modifications each year.  As such, it remains important to conduct ongoing monitoring of the effectiveness of vaccines against circulating strains. 

Current evidence shows that the protection vaccines provide against infection and disease can decline over time.  Factors such as age, underlying medical conditions (e.g., diabetes, cancer), history of prior infection type of vaccine, total number of doses administered, and time elapsed since the most recent dose can also influence the effectiveness of vaccines.  These factors can contribute to a reduction in circulating antibody levels, the key component that helps prevent infection.  The SPRINT-KIDS surveillance program hopes to provide up-to-date data to us to understand how well vaccines are working to prevent illness in the children at any given time due to common vaccine-preventable viral infections.

The SPRINT-KIDS Vaccine Effectiveness Project is collecting detailed data on children who are tested for various respiratory pathogens along with information about their symptoms, illness severity, and vaccination history.  The project team meticulously reviews records of children tested for respiratory infections, extracting key data from their medical records.  This data is shared in real-time with the Public Health Agency of Canada, enabling weekly assessments of vaccine effectiveness in Canada’s pediatric population.