Determination of the optimal SARS-CoV-2 vaccination strategy to achieve a robust and long-lasting immune response

Global COVID-19 vaccine distribution has been inequitable, with high-income countries afforded widespread access to vaccines and boosters, while among the low-income countries only 2 percent of individuals are vaccinated. Consequently, over 50 percent of the world’s population remains unvaccinated. Fortunately, however, data from vaccinated cohorts can inform the most efficient and effective community-level vaccination strategies for the unvaccinated populations. Currently approved mRNA vaccines were initially tested with dosing intervals of 21-28 days; however, this may lead to suboptimal immunity. Further, data informing the optimal timing and frequency of booster doses is lacking. This project will answer critical questions regarding the optimal vaccination strategies to achieve a robust long-lasting immune response. In this study I will employ data from a prospective national cohort of adult paramedics, providing sociodemographic data and serum blood samples. I will identify the optimal vaccination strategies to achieving a robust immune response at 12, 18 and 24 months, including examining differences between sex, race, and age. These data will inform ongoing global vaccination efforts, to maximize efficiency and long-term protection.

End of Award Report – June 2025

Results

My project led to several important findings that have helped improve how we understand and manage COVID-19, especially for frontline workers like paramedics. One major result was showing how immunity from COVID-19 vaccines can decrease over time. This helped inform decisions on when people should get booster doses to stay protected—an issue that was especially important for high-risk groups in British Columbia.

We also found that bivalent booster vaccines—which target both the original virus and newer variants—produced stronger immune responses than earlier vaccines. This helped guide vaccine policies and gave reassurance that updated vaccines were working better for people on the front lines. Another exciting part of the research was studying how many vaccines people had and how that affected their immunity against newer variants like Omicron. We also looked into a theory called antibody imprinting to understand how previous exposure to the virus or vaccines might shape future immune responses. These findings offered new insights into how the immune system remembers and reacts to COVID-19.

In addition, we explored the link between COVID-19 infections and long-term symptoms among vaccinated paramedics. This helped raise awareness of post-COVID or “long COVID” issues, even among people who had been vaccinated. My work didn’t just stay in academic journals—it was shared with public health officials and helped improve how COVID-19 is managed among paramedics and other healthcare workers in BC and across Canada. The results also have broader value for similar workers across North America.

Impact

The research supported by my partnered award has already made a meaningful impact on public health in British Columbia and beyond. Our findings have helped guide decisions about when booster COVID-19 vaccines should be given and provided evidence supporting the use of bivalent booster vaccines to strengthen protection, especially among frontline healthcare workers like paramedics.

My work has also raised awareness of long COVID symptoms among vaccinated individuals and contributed to improving occupational health policies for high-risk professionals. Public health officials and healthcare leaders have used our findings to shape vaccine rollout strategies, protect essential workers, and reduce COVID-related risks in real-world settings.

In addition, the project has led to the publication of 10 peer-reviewed studies, which are already being cited by researchers and health agencies, showing that our work is contributing to both scientific knowledge and real-world decision-making.

Potential Influence

The research supported by my partnered award has strong potential to continue influencing vaccine policy, occupational health practices, and pandemic preparedness. As COVID-19 evolves and new variants emerge, the evidence we’ve generated on vaccine durability, booster timing, and immune response patterns will help shape ongoing vaccination strategies and booster recommendations for high-risk populations across Canada and internationally.

Beyond COVID-19, our research framework—particularly our approach to studying immune responses in real-world frontline settings—can serve as a model for evaluating vaccines in future outbreaks or public health emergencies. The methodologies and partnerships developed through this award also lay the foundation for new collaborative research that could expand into other areas of infectious disease control and immunization science. Ultimately, this work will continue to guide decision-makers in protecting essential workers, refining immunization schedules, and adapting public health interventions to emerging challenges.

Next Steps

I will be focusing on further research on Long COVID (post COVID condition) burden among paramedics in Canada. Will also try to compare the burden of Long COVID among several essential healthcare workers in Canada