People who have already had Covid-19 ‘should not be blasé’ about the virus because as one in 10 people could catch it again, a top scientist has warned.
His comments come as Prime Minister Boris Johnson goes into a fortnight of self-isolation after coming into close contact with an MP who later tested positive.
The PM, however, claims he is ‘bursting with antibodies’ after he ended up in intensive care during his own severe bout of Covid-19 in the country’s first wave.
Professor Altmann, however, said that although the risk of catching the disease again is ‘low’, it could happen to as many as one in 10 people and recovered patients should still take it very seriously.
Scientists have reported dozens of cases of coronavirus reinfection but the circumstances around them are often hazy, with it possible that some people never recovered from the first illness and others with dysfunctional immune systems.
The Imperial expert said there had been around 25 ‘hard confirmed cases’ in the world of people catching Covid-19 twice, but that researchers think it is far more common. Whether it is more or less serious, he said, is still a topic for debate.
Professor Danny Altmann, an immunologist at Imperial College London, said people who have already had coronavirus ‘should not be blasé’ about the risk of catching it a second time
‘I read a lot about people saying one can’t be reinfected or there’s practically zero risk of reinfection,’ he said on BBC Radio 4’s Today programme.
‘That’s not quite true because, of 50million plus cases of infection in the world, we have more than 25 hard confirmed cases of reinfection, which you might say is negligible, but that’s because academically we set the bar quite high for defining reinfection.
‘You have to be SARS positive and then negative and then positive again and [with] different virus sequences and things.
‘Anecdotally, I think most of us think the rate of reinfection is quite a lot higher than that but not enormous.’
Professor Altmann’s comments come as the Prime Minister announced he has had another Covid scare after catching the virus in April left him in critical condition.
Boris Johnson today insisted he can run the country by Zoom as he hit back against criticism of his mask-free meeting with a coronavirus-infected Tory MP.
Mr Johnson will spend two weeks alone in his flat at 11 Downing Street after he met with Conservative MP Lee Anderson last week and Anderson later tested positive.
The move comes at a time of extreme turbulence in Downing Street after the PM’s top aides Dominic Cummings and Lee Cain both resigned last week.
But Mr Johnson insisted in a Twitter video today that he is ‘fit as a butcher’s dog’.
He said: ‘It doesn’t matter that we were all doing social distancing, it doesn’t matter that I’m fit as a butcher’s dog, feel great – so many people do in my circumstances.
‘And actually it doesn’t matter that I’ve had the disease and I’m bursting with antibodies. We’ve got to interrupt the spread of the disease and one of the ways we can do that now is by self isolating for 14 days when contacted by Test and Trace.’
On Thursday, the Prime Minister held a 35-minute meeting with a group of MPs including Mr Anderson who later tested positive for the virus. Pictured: The PM and Mr Anderson at Thursday’s meeting
The PM is correct when he says it ‘doesn’t matter that I’ve had the disease’ because there is scientific proof people can get it more than once.
Studies have found patients who tested positive for Covid-19, then tested negative, have later tested positive a second time with a genetically different version of the virus, meaning it was a new strain that entered their body.
Confirmed reports are not common but the ones that do exist prove it is possible.
People with stronger immune responses after their first bout of illness are more likely to be able to fend off the infection a second time.
This is because a strong early immune response means the body creates more white blood cells – such as antibodies and T cells – that are critical to building a defence against the virus in case it gets into the body again.
Strong immunity means that someone’s body can destroy the virus as soon as it gets into the body and before it causes any symptoms.
It is not clear whether people can pass on the virus if they don’t get Covid-19 symptoms when they get a second infection.
Professor Altmann said: ‘My bottom line is not to be in any way alarmist because whatever the risk is it’s low.
‘My sense from some of our data and other people’s data is that it’s the people who’ve made the poorest, the most negligible antibody response the first time round who are most at risk of reinfection.
‘So that’s maybe 10 per cent of everybody out there who’s been infected in the first wave.’
He said that everyone who has tested positive for coronavirus in the past should still be strict about following social distancing rules and wearing masks, and act as if they have never had it.
He added: ‘I’ve got one take home message on the reinfection discussion: it’s not to be blasé because you’ve had it or you think you’ve had it because the risk is still there.’