Covid reinfection 'possible' but 'rarely documented', Hiqa advises

Dr Máirín Ryan: "New evidence has demonstrated that reinfection can occur following recovery from SARS-CoV-2 infection." File Picture: Brian Lawless

Health watchdog Hiqa has said the phenomenon of Covid-19 reinfection "has significant policy implications" in how to deal with the disease, in new advice submitted to the National Public Health Emergency Team (Nphet).

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 14 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.”

The advice to Nphet said: "Reinfection with SARS-CoV-2, although rarely documented, is possible."

It said Anti-SARS-CoV-2 IgG and neutralising antibody seropositivity is maintained in most individuals for two-to-six months post-infection, although further research was required.

It also stressed that the current understanding of the immune response to the coronavirus is limited. 

"The presence of antibodies does not mean that the person has immunity, and cellmediated immunity (memory B-cells, T-cell responses) are important," it said. 

"The relative importance of antibody versus cell-mediated responses is not known."

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 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.”

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.