Helen Petousis-Harris’s 2020 Vision for Vaccine Safety

In this 2020 presentation, Associate Professor Helen Petousis-Harris discusses vaccine safety assessment and the challenges surrounding covid-19 vaccine development. She begins by tracing vaccine hesitancy back to 18th-century fears about cowpox inoculation, drawing parallels to contemporary conspiracy theories about microchips and 5G technology. She presents the “vaccine confidence life cycle” – a pattern where acceptance is high when disease threatens, then declines as the disease fades and focus shifts to vaccine safety concerns, leading to disease resurgence.

Petousis-Harris outlines the standard vaccine safety process from small Phase 1 trials through Phase 4 post-market surveillance involving millions of people. She emphasises that modern technology – administrative databases, artificial intelligence, and real-time statistical methods – enables detection of extremely rare adverse events, perhaps one in a million. She cites a Danish study tracking 650,000 children as an example of using “big data” to definitively answer safety questions, in this case finding no link between MMR vaccine and autism.

Addressing covid-19 vaccine development speed, she explains two key factors enable compressing a typical 10-15 year timeline: substantial funding eliminating financial risk, and running development phases in parallel rather than sequentially. She assures audiences that no safety steps are being skipped and that comprehensive post-market surveillance will be implemented. However, she dedicates significant attention to what she frames as the greater threat: an “infodemic” of misinformation spreading faster than truth on social media. She concludes by calling for collective responsibility to combat misinformation, arguing that building trust and “inoculating against misinformation” are as crucial as the vaccines themselves.