Why do some people get Covid twice and others not at all?
A GP has explained why some people are catching Covid-19 more than once after Labour leader Keir Starmer tested positive for coronavirus for a second time earlier this week.
Starmer previously tested positive last October and it's his sixth period in isolation since the pandemic began. But many people will have not caught it once since the pandemic began in early 2020.
More than 150,000 people have now died within 28 days of a positive Covid test in the UK since the pandemic began. But there is good news from hospitals despite the number of Covid patients growing massively — you can read what that is here.
Covid rates are soaring, with more people relying on lateral flow tests to check whether or not they are infected — you can read key things on LFTs, including what a faint line means on your result, here.
Dr Alan Stout, chair of the British Medical Association's GP committee in Northern Ireland, said people "can absolutely get Covid twice" and it explained why case numbers here remain high. Dr Stout told Belfast Live : "The vast majority of people we're seeing in the daily figures will have had some sort of previous infection. Keir Starmer is a good example as what he will have now is almost certainly the Omicron variant and previously, he may well have had the Delta or Alpha variant.
"One of the difficulties with the variants is that having one of the previous ones doesn't necessarily protect you from the next. That has become quite clear as the previous Delta infection we know now gives you virtually no protection or natural immunity from Omicron. That's the simplest reason why people are contracting Covid twice - it's down to the different variants."
While cases of people catching Covid-19 more than once have been reported throughout the pandemic, concern is growing as immunity wanes and new variants emerge.
Dr Stout added: "That's why the booster has been so important for Omicron because we've known that the level of immunity given by the first two vaccine doses has started to wane. Hence the booster was giving that extra level of protection but it was actually giving protection above and beyond, which is then preventing people getting Omicron or certainly becoming seriously unwell with it."
But Dr Stout said research around reinfections is still in its infancy: "That's one of the things we're learning as we go along and yet there is quite a lot of data and evidence around what protection people have, which then helps with the planning in terms of vaccination. One of the big things we don't know is around any next variant. Equally while we know there will definitely be more variants, whether we get a more severe one or they become less and less severe with time and evolution is another significant possibility."
People are also being urged to test regularly with lateral flow tests, particularly before they come into contact with others. Anyone who receives a positive lateral flow result must self-isolate immediately.
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