For vaccine dosing decisions, past experience and best guesses won the day in the mad rush to beat back the pandemic. Modelling tools might have made a difference.
Jennifer Linderman, a systems biologist at the University of Michigan in Ann Arbor, says such approaches could be useful for guiding dose decisions in the future. “We’re in a position now where, going forward, we can be much more intentional about vaccine design,” she says.
“This is an important area,” says Marco Cavaleri, head of biological health threats and vaccines strategy at the European Medicines Agency in Amsterdam. “The more we can refine these techniques, the more we will be prepared in the future.”Last June, the US Food and Drug Administration convened a workshop at which researchers discussed best practices for modelling vaccine dose–response relationships.
Over time, their model — dubbed the Vaccine Simulator — grew in sophistication. And before efficacy results were even known for the first wave of COVID-19 vaccines, Kierzek and van der Graaf had already concluded that longer dosing intervals than those being evaluated would yield improved antibody responses
AstraZeneca scientists are now using Certara’s model to simulate scenarios not captured by earlier clinical studies of the company’s vaccine. They are interrogating immune responses in populations that were under-represented in trials — particular ethnic groups, for example, and immunocompromised people — to predict who might benefit from non-standard dosing. And they are looking at long-term immunity trends to inform optimal timing of booster-dose regimens.