The Health Information and Quality Authority (HIQA) has today published its advice to the National Public Health Emergency Team (NPHET) on the duration of immunity (and protection from reinfection) following SARS-CoV-2 infection.
This advice was informed by a review of international evidence including 19 large cohort studies of reinfection involving over 640,000 previously infected individuals. It was also informed by 13 studies on immune memory response along with expert opinion, from the COVID-19 Expert Advisory Group.
Dr Máirín Ryan, HIQA’s Deputy CEO and Director of Health Technology Assessment, said: “We have advised NPHET that the period of presumptive immunity should be extended from six to nine months post-infection. Across all the studies we examined, the risk of SARS-CoV-2 reinfection was consistently low, with no increase in infection risk over time. In addition, studies suggests that most people develop immune memory after a SARS-CoV-2 infection that lasts for at least nine months.”
Dr Ryan continued: “Increasing the period of presumptive immunity from six to nine months has widespread positive implications for people. For example, a person who has COVID-19 in the last nine months would be exempt from serial testing. A change would also increase the number of under-50s who only need one dose of a COVID-19 vaccine to be considered fully vaccinated. It would also have implications for the implementation and roll-out of the proposed ‘green certificates’. It will be important that any policy changes and the evidence behind them are clearly communicated and consistently applied.”
The potential impact of new variants on natural immunity is evolving rapidly and needs to be kept under review. Future changes in policy should be informed by the latest international evidence and national surveillance data.
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