HIQA publishes documents on the potential for reinfection following a SARS-CoV-2 infection

Date of publication:

The Health Information and Quality Authority (HIQA) has today published advice it submitted to the National Public Health Emergency Team (NPHET) to support its response to COVID-19. The publication of this advice is accompanied by a supporting evidence synthesis report.

HIQA previously published evidence summaries on many aspects of the immune response following SARS-CoV-2 infection. In this update, HIQA has reviewed new evidence relating to the possibility of reinfection following recovery from SARS-CoV-2, as well as studies with longer follow-up looking at the duration of immunity following infection.

Dr Máirín Ryan, HIQA’s Deputy CEO and Director of Health Technology Assessment, said: “New evidence has demonstrated that reinfection can occur following recovery from SARS-CoV-2 infection. Worldwide, at least fourteen patients have been infected twice by SARS-CoV-2; these reinfections were confirmed by genetic evidence that showed the first and second infections were caused by different viral strains. It is important to remember, however, that these are rare events.”

Dr Ryan continued: “The phenomenon of reinfection has significant policy implications. Infection prevention and control, isolation and contact tracing considerations are not likely to differ for cases of reinfection compared with the first infection. Therefore, all public health advice, including hygiene and physical distancing, should apply to those who have recovered from a SARS-CoV-2 infection as immunity from reinfection cannot be assumed.”

The evidence summary also reviewed the current evidence on the maximum duration of immunity following infection. Dr Ryan said: “Evidence from 22 studies suggests that IgG antibody levels (the most common antibody in the blood) are sustained for at least two months after infection, and for some even up to six months. The levels of neutralising antibodies (that can neutralise viruses like SARS-CoV-2), decline over time, especially in the later stages of follow-up. While this doesn’t offer a full picture of the body’s response to SARS-CoV-2, these data have implications for vaccine development, antibody testing and immunotherapy going forward.”

HIQA also published a scoping evidence review on convalescent plasma therapy conducted at the request of the Department of Health. This scoping review looked at the use of convalescent plasma as a potential treatment for patients with COVID-19, experiencing, or who are at risk of experiencing, a severe course of disease.

The documents published today are available from the link at the top of the page.

Further information:
Marty Whelan, Head of Communications & Stakeholder Engagement
085 8055202, mwhelan@hiqa.ie

Notes to Editor:

  • HIQA has today published the following documents to inform NPHET’s response to COVID-19:
    • Advice to the National Public Health Emergency Team: Duration of immunity and potential for reinfection with SARS-CoV-2.
    • Evidence summary of the duration of antibody responses and reinfection following SARS-CoV-2 infection.
    • Evidence summary protocol of the duration of antibody responses and reinfection following SARS-CoV-2 infection.
    • Scoping report on convalescent plasma as a treatment for COVID-19
  • Twenty-two studies were retrieved that investigated the IgG and or neutralising antibody response beyond 60 days post-infection.
    • IgG is a class of antibodies that is crucial for immune memory and long-term immunity. It is the most abundant antibody class in humans.
    • Neutralising antibodies prevent infectious particles and viruses from infecting cells by neutralising or inhibiting their biological effect.
  • Many current vaccine design efforts focus on generating a strong neutralising antibody response to provide protection from infection. Our findings of a reduction in neutralising capacity over time suggests immunity may not be long-term. If vaccination results in a similar response, consideration may be given to the need for repeat or ‘booster’ doses.
  • Convalescent plasma from patients recently recovered from a disease contains antibodies which, when transfused into others, may provide passive immunity to the disease in recipients. The intervention has historically been used to treat conditions for which there was no vaccine or pharmacological intervention.
  • Based on the available studies, the review found limited evidence that convalescent plasma is an effective treatment for COVID-19. In terms of safety, the rate of severe adverse events appears to be low. In cases where there are no other alternative treatments available, convalescent plasma may offer a potential treatment option for patients at high risk of a severe course of the disease.
  • Since September 2020, HIQA has provided evidence based advice in response to requests from NPHET.
  • HIQA’s advice to NPHET is informed by research evidence developed by HIQA’s COVID-19 Evidence Synthesis Team, with expert input from HIQA’s COVID-19 Expert Advisory Group.
    • o    The topics HIQA researches are outlined and prioritised by NPHET to ensure that they have rapid access to the best available evidence relevant to the SARS-CoV-2 outbreak.
  • HIQA’s COVID-19 Evidence Synthesis Team produces a variety of outputs including rapid health technology assessments, scoping reports, rapid reviews of public health guidance, and evidence summaries, supplemented by an evidence-to-advice framework to guide the development of advice, where appropriate.
  • HIQA’s COVID-19 Expert Advisory Group is a multidisciplinary group, comprising nominated representatives from the relevant clinical specialties and areas of expertise, methodology experts, and public representation.