A series of three evidence summaries was conducted by HIQA to help inform the work of the National Immunisation Advisory Committee (NIAC). These three reviews were conducted in sequence, with the second and third reports based on updated literature reviews. The initial report examined the duration of protective immunity following COVID-19 vaccination (efficacy and effectiveness) in all populations aged 12 years and older. The first update focused on healthcare workers, while the second update focused on individuals with underlying conditions.

All three evidence summaries addressed the following policy question:

“What is the evidence relating to the duration of protective immunity (vaccine efficacy and effectiveness) following COVID-19 vaccination?”