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 (protection from reinfection) following SARS-CoV-2 infection. 

HIQA has 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. 

HIQA reviewed 65 large observational studies involving over 1.4 million previously infected individuals, including 10 studies with over 12 months’ maximum follow-up. HIQA found that the risk of SARS-CoV-2 reinfection was low within the timeframe of these studies. There was also evidence to suggest that vaccination provides additional protection to those previously infected with SARS-CoV-2.

The majority of the studies were undertaken during periods of stringent public health measures and before the widespread circulation of the Delta variant. It is therefore uncertain how applicable the findings from these studies are to the current context of relaxed public health measures and a more transmissible Delta variant. 

Michelle O’Neill, HIQA’s Deputy Director of Health Technology Assessment said: “Even if you have been previously infected with SARS-CoV-2, it is possible that you can get infected again and spread the virus to others. We recommend that you continue to follow to public health guidance, and get vaccinated even if you have already recovered from COVID-19, as the vaccine will provide you with an additional layer of protection.” 

Based on the evidence to date, reinfection with SARS-CoV-2 is still an uncommon occurrence, but it is more likely for certain groups, such as healthcare workers due to their increased risk of exposure. 

Michelle O’Neill continued: “Any extension to the period of presumed protective immunity may have unintended negative consequences particularly as the incidence of the virus is currently very high.”  

HIQA has advised that this issue should be kept under review with updates informed by national surveillance data and research evidence.

You can find these documents at the link at the top of the page.

Ends.

Further information:

Marty Whelan, Head of Communications & Stakeholder Engagement

01 814 7480/085 805 5202, mwhelan@hiqa.ie

Notes to Editor:

• HIQA has today published the following documents to inform NPHET’s response to COVID-19: 
  • Advice to NPHET - Duration of immunity (protection from reinfection) following SARS-CoV-2 infection
  • Evidence summary - Duration of immunity (protection from reinfection) following SARS-CoV-2 infection

• HIQA has reviewed this question eight times, with the last review published on 3 June 2021. 

• NPHET asked HIQA to provide advice on the following policy question:
  • “How long does protective immunity (that is, prevention of antigen or RT-PCR confirmed reinfection) last in individuals who were previously infected with SARS-CoV-2 and subsequently recovered?”

• HIQA provides evidence-based advice to NPHET to inform public health policy, advice and practice in the context of COVID-19. HIQA’s advice is informed by research evidence developed by HIQA’s COVID-19 Evidence Synthesis Team.

• This advice to NPHET is developed with expert input from HIQA’s COVID-19 Expert Advisory Group. The COVID-19 Expert Advisory Group, chaired by Dr Máirín Ryan, is a multidisciplinary group, comprising nominated representatives from the relevant public health and clinical specialties, methodology experts, and public representation.

• The topics HIQA researches are outlined and prioritised by NPHET to ensure rapid access to the best available evidence relevant to the SARS-CoV-2 outbreak.