People may need booster jabs of the Covid-19 vaccine to protect against long-term infection, health experts revealed.
And those who have had Covid-19 can be infected a second time, the Health Information and Quality Authority (Hiqa) warned.
There was good news this week when it was announced that a Covid-19 vaccine being developed by two leading pharmaceutical companies has been 90% effective at trials.
Pfizer and BioNTech, who are working on the project together, said that, in most cases, preventing infection was achieved seven days after taking two doses, and 28 days after taking the first.
But while Hiqa welcomed the developments in vaccine trials, it warned that immunity against the virus does not seem to last forever.
Antibodies against Covid-19 remain in the blood system for at least two months after a person becomes infected.
For some, this immunity can last for up to six months, Hiqa’s review of the latest international evidence found.
But the fact that antibodies against Covid eventually leave the body means that antibodies from any vaccine could also fail to protect against long-term reinfection.
This means that if vaccination produces a response in the body similar to infection, there might be a need for repeat or “booster” doses.
Dr Máirín Ryan, Hiqa’s Deputy CEO and Director of Health Technology Assessment, people must remember that they are not immune to Covid - even if they have already been infected.
And researchers must follow up with those who receive a Covid-19 vaccine, when it is developed.
Dr Ryan told the Irish Mirror: “Reinfection is rare, but it is confirmed that it is possible.
“If you have had Covid-19, you cannot assume that you are immune to it.
“It is still important to follow all the public health guidelines, including hygiene and physical distancing.
“Those who have had Covid-19 also need to remember that if they develop symptoms again, they still need to self-isolate and contact their GP.”
A lack of long-term immunity has implications for how often people would need to get the vaccine.
Dr Ryan said: “If the antibodies in those who have been infected wane over time, there’s a possibility that the antibodies from a vaccine could wane over time as well.
“We need to follow up with this and find out whether those who get the vaccine need regular booster doses.”
Booster jabs are needed in other diseases, such as the seasonal flu.
Hiqa’s ongoing reviews of the latest evidence in relation to Covid-19 help support the National Public Health Emergency Team’s (NPHET) response to the global pandemic.
