Measuring waning protection from seasonal influenza vaccination during nine influenza seasons, Ontario, Canada, 2010/11 to 2018/19.

BackgroundWaning immunity from seasonal influenza vaccination can cause suboptimal protection during peak influenza activity. However, vaccine effectiveness studies assessing waning immunity using vaccinated and unvaccinated individuals are subject to biases.AimWe examined the association between time since vaccination and laboratory-confirmed influenza to assess the change in influenza vaccine protection over time.MethodsUsing linked laboratory and health administrative databases in Ontario, Canada, we identified community-dwelling individuals aged ≥ 6 months who received an influenza vaccine before being tested for influenza by RT-PCR during the 2010/11 to 2018/19 influenza seasons. We estimated the adjusted odds ratio (aOR) for laboratory-confirmed influenza by time since vaccination (categorised into intervals) and for every 28 days.ResultsThere were 53,065 individuals who were vaccinated before testing for influenza, with 10,264 (19%) influenza-positive cases. The odds of influenza increased from 1.05 (95% CI: 0.91-1.22) at 42-69 days after vaccination and peaked at 1.27 (95% CI: 1.04-1.55) at 126-153 days when compared with the reference interval (14-41 days). This corresponded to 1.09-times increased odds of influenza every 28 days (aOR = 1.09; 95% CI: 1.04-1.15). Individuals aged 18-64 years showed the greatest decline in protection against influenza A(H1N1) (aORper 28 days = 1.26; 95% CI: 0.97-1.64), whereas for individuals aged ≥ 65 years, it was against influenza A(H3N2) (aORper 28 days = 1.20; 95% CI: 1.08-1.33). We did not observe evidence of waning vaccine protection for individuals aged < 18 years.ConclusionsInfluenza vaccine protection wanes during an influenza season. Understanding the optimal timing of vaccination could ensure robust protection during seasonal influenza activity.

"I try to take all the time needed, even if i do not have it!": Knowledge, attitudes, practices of perinatal care providers in canada about vaccination.

Objective: Successful clinical conversations about vaccination in pregnancy (pertussis, COVID-19, and influenza) are key to improving low uptake rates of both vaccination in pregnancy and infancy. The purpose of this study was to understand Canadian perinatal care providers' knowledge, attitudes, and practices around vaccination in pregnancy. Methods: Qualitative interviews with 49 perinatal care providers (nurse practitioner, general practitioner, registered nurse, registered midwife, obstetrician-gynecologist, and family physicians) in 6 of 13 provinces and territories were deductively coded using directed content analysis [1] and analyzed according to key themes. Results: Participants detailed their professional training and experiences, patient community demographics, knowledge of vaccines, views and beliefs about vaccination in pregnancy, and attitudes about vaccine counselling. Providers generally described having a good range of information sources to keep vaccine knowledge up to date. Some providers lacked the necessary logistical setups to administer vaccines within their practice. Responses suggest diverging approaches to vaccine counselling. With merely hesitant patients, some opted to dig in and have more in-depth discussions, while others felt the likelihood of persuading an outright vaccine-refusing patient to vaccinate was too low to be worthwhile. Conclusion: Provider knowledge, attitudes, and practices around vaccination varied by professional background. To support perinatal providers' knowledge and practices, clinical guidelines should detail the importance of vaccination relative to other care priorities, emphasize the positive impact of engaging hesitant patients in vaccine counselling.