Immunity after Covid-19 infection can last up to six months, the State’s health watchdog has advised.
This is twice the 12-week period that currently applies as guidance in Ireland.
As The Irish Times reports, post-infection guidance for close contacts should be extended to six months in line with the new evidence, according to the Health Information and Quality Authority (Hiqa).
Hiqa’s recommendation will be considered by the National Public Health Emergency Team (Nphet), which had asked it to review the international evidence and expert opinion on the issue.
The studies Hiqa examined were conducted prior to last December. Since then, new variants of SARS-CoV-2 have been found and the vaccine rollout has begun.
As a result, it says the applicability of the findings to the new strains and vaccinated populations is unknown.
“We have advised Nphet presumptive immunity should be extended to six months post-infection. The risk of re-infection with SARS-CoV-2 is low and no evidence was found to suggest that immunity wanes over this period,” said Dr Máirín Ryan, Hiqa’s deputy chief executive and director of health technology assessment.
The review identified five studies reporting low rates of reinfection up to seven months following initial infection.
In relation to the long-term duration of immune responses, it found that, while there may be a waning of antibody responses over time, T- and B-cell responses persist for up to eight months post-infection.
Dr Ryan added “Our advice has implications for a number of policy areas including exemption from close contact status, serial testing in selected work settings and testing prior to admission or transfer to a healthcare facility."