Last week, we published three reviews on vaccine immunity to inform the work of the National Immunisation Advisory Committee (NIAC).
We reviewed international evidence in order to assess the duration of protective immunity following COVID-19 vaccination in the general population and in specific subgroups. The initial review examined the duration of protective immunity following COVID-19 vaccination 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.
We found that while the risk of breakthrough infection increased over time, the overall evidence suggests that COVID-19 vaccination continues to provide strong protection against severe disease and mortality for at least six months post-vaccination. However, some studies suggest that there is waning protection for older adults and in those with immunocompromising conditions.
However, some uncertainty regarding protection after six months was found, especially in relation to new variants of concern and changing public health measures. Therefore, we have advised anyone who has been offered a booster dose to avail of it and give themselves the best protection possible.
In November, we issued advice to the National Public Health Emergency Team (NPHET) on the duration of immunity (protection from reinfection) following SARS-CoV-2 infection. We advised that the current public health policy which assumes a period of protective immunity of nine months post-infection with SARS-CoV-2 should not be changed.
As many of the studies reviewed were undertaken during periods of stringent public health measures and before the widespread circulation of the Delta or Omicron variants, it is uncertain how applicable the findings from these studies are to the current context of more relaxed public health measures and more recent variants of concern.
Michelle O’Neill, our Deputy Director of Health Technology Assessment recommended that everyone should: “Follow public health guidance, and get vaccinated even if they have already recovered from COVID-19, as the vaccine will provide them with an additional layer of protection.”
We advised NPHET that this issue should remain under review with updates informed by national surveillance data and research evidence.
In addition to this work, we also published and updated the following evidence synthesis in recent weeks:
- Database of public health guidance on COVID-19
- International review on protective measures for groups vulnerable to COVID-19
- International review of public health guidance for residential care facilities.
View our latest reviews and advice on COVID-19 here.