“Technology and understanding of how pathogens do their work have expanded the pace of development,” Dr. Halperin says. “We can swap antigens more quickly and pursue a broader range of pathogens.” Another historical shift has been programmatic. Early “universal” programs went after pathogens that affected everyone. Today, as those victories hold, research and policy are also tackling diseases concentrated in subpopulations. “We’re seeing a move toward vaccines for groups at particular risk, including older adults, infants, health care workers, or specific communities hit hardest during outbreaks,” Dr. Tunis says. The result is innovation with a finer point: RSV immunization in pregnancy to protect infants, targeted monoclonal antibody programs for newborns, and agestratified indications for older adults. Vaccine Research Vaccine development is a relay across disciplines and sectors. Dr. Sadarangani describes a lifecycle that begins long before public awareness. “A lot of time is spent in development before anyone’s heard of it,” he says. Preclinical work in laboratories and animal models identifies candidate antigens, refines formulations, and examines dosing strategies. Epidemiologic studies map disease burden and identify the populations most likely to benefit. If a vaccine candidate looks promising, it enters human testing. Phase 1 studies, typically in dozens of healthy adults, assess safety and initial immune responses. Phase 2 trials, with hundreds of participants, continue safety monitoring and probe immunogenicity more deeply. Phase 3 trials, with thousands to tens of thousands involved, demonstrate efficacy against disease, often through randomized, placebo-controlled designs. “Phase 2 and 3 trials are massive undertakings,” Dr. Sadarangani says. Academic networks can and do conduct early trials, sometimes with public funding from agencies such as the Canadian Institutes of Health Research (CIHR) and the Natural Sciences and Engineering Research Council of Canada, or with small biotech partners. As costs and scale grow, large manufacturers usually step in to produce vaccines at greater volume and to execute the biggest trials. Even then, the science is only at the halfway mark. Image: Public Health Agency of Canada 22 | 2026 | Issue 2 Issues and People
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