Research has found that people who have recovered from coronavirus infection have immunity only for up to six months.

The study of the experience worldwide, found that after infection, immunity is sustained for at least two months and for some up to six months.

People who have recovered from a Covid-19 infection must continue to follow all public health advice, including hygiene and physical distancing, according to a new study by the Health Information and Quality Authority.

HIQA conducted the review of the potential for reinfection following a Covid-19 infection at the request of the National Public Health Emergency Team.

The study says that reinfection cases are rare events and to date 14 patients worldwide have been infected twice.

Genetic evidence shows that the first and second infections were caused by different strains.

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HIQA’s Deputy CEO and Director of Health Technology Assessment said based on its research, it may not be possible for a Covid-19 vaccine to produce long-term immunity and a booster may be needed.

Speaking on RTÉ’s News at One, Dr Máirín Ryan said this is not that surprising as immunity does wane over time with a number of vaccines and boosters are required.

Dr Ryan said one element of the antibody response that is being noted – neutralising antibodies – are waning after a couple of months.

She said: “A lot of vaccines are designed to cause the body to produce neutralising antibodies … if they behave in the same way as what we’re seeing with the natural infection, then it means that the immunity that’s produced by the vaccine may wane over time.”

She said it may not be possible therefore for the vaccine to produce long-term immunity and people may need booster doses.

Dr Ryan said people who have had the coronavirus and who show symptoms that are consistent with Covid-19, should continue to observe all the public health advice and contact their GP for a test as they “can’t assume that immunity from re-infection is taking place”.

She acknowledged that the documented cases of re-infection are rare, but as earlier tests were done on those who were very symptomatic and not those who were mildly symptomatic or asymptomatic, it is “very likely that there are substantially more cases of re-infection out there and more cases will be reported as we go forward”.