The UK appears to have reached the peak of its coronavirus outbreak. On April 22 health secretary Matt Hancock told parliament that the UK’s lockdown measures that have been in place for four-and-half weeks appear to be having an effect as the number of daily new deaths from the virus are no longer rising sharply, although they remain at a high level.
While the UK is still very much in the grip of its Covid-19 outbreak, thoughts are already turning to the possibility of life after lockdown. But while ministers debate how and when to ease restrictions, and the country looks to other European countries that are just starting to peel back their lockdowns, one thing will be in the back of many minds: the possibility of a second outbreak of Covid-19. How can the UK ease its restrictions without seeing a repeat of the last two months?
When the first wave of an outbreak is sufficiently large, the majority of a population can become immune to disease. The chances are then much smaller that a susceptible person will come into contact with an infectious individual. But this so-called herd immunity can only be reached by letting the virus pass through the entire population, which would lead to disease and subsequent recovery in most people but also come at an unacceptably high cost of lives, or through vaccination which mimics an infection without causing disease.
But with a safe, effective vaccine likely a year or more away from being available for general use, the majority of the UK population will still be susceptible to infection when the lockdown is lifted and a second wave hits the country. We don’t know how many people in the UK are likely to be immune to Covid-19, but initial studies out of California and the Netherlands indicate that perhaps as few as three per cent of people have antibodies that can defend against the virus. In certain parts of Germany and France, however, this number seems to be much higher: up to 14 per cent.
Thomas House, a reader in statistics at the University of Manchester who is modelling the current epidemic says that social distancing measures in the UK and elsewhere may have flattened infection curves but left many individuals at risk of infection. “The bad news seems to be that where people have tried to look in the community and other places there hasn’t been a tremendously high level of acquisition of immunity. That means it doesn’t look like we can come straight out of lockdown and back to normal,” he says.
So is a second wave of infection inevitable? Jasmina Panovska-Griffiths, a senior research fellow and lecturer in mathematical modelling at University College London says we can learn from history and use modelling to explore scenarios to prevent it. The four major flu pandemics of the past century – the Spanish flu, Asian flu, Hong Kong flu and swine flu – came in several waves, too. The 1918 Spanish flu pandemic that killed more than 50 million people hit in three waves, with the second killing more people than the first. The 2009 swine flu pandemic started in spring and, in the temperate northern hemisphere, was followed by a second, larger wave in the autumn.
In the fight against the coronavirus outbreak, the UK will have to keep subsequent waves as low as possible in order to reduce the burden on its healthcare services. “What we will see when the second wave comes is going early [into lockdown] doesn’t protect you from that, because we still have a lot of susceptibility in the population,” says House.
One of the characteristics that makes the course of the coronavirus epidemic so difficult to predict is the incubation period, which is the time between the infection and when a person becomes infectious. It takes up to 14 days for an infected individual to show symptoms so they may unknowingly spread the virus to people around them. “You want to catch people during the latent period. When they’ve not had a chance to infect people yet,” says House. More testing and contact tracing will be the key. Contact tracing starts with a call to someone who has tested positive for coronavirus, and then follow-up with everyone that person was in contact with to see if they too need to be isolated. Hancock has said that the UK will start large-scale contact tracing within weeks, but an NHS app to do just that has already become mired in privacy and technological issues.
Despite their close proximity to China, Singapore along with South Korea, Hong Kong and Taiwan have managed to flatten their curves through early lockdown measures, mass testing and contact tracing. Kenji Shibuya, director of the Institute for Population Health at King’s College London, says there are many lessons to learn from these countries as, despite the early successes in handling their outbreaks, travellers from the US and Europe began reimporting the virus which has led to a sudden resurgence in infection. “It’s important to aggressively test and isolate. That’s the basics at the beginning,” says Shibuya. “But if you contain the first wave, to prepare for the second wave it’s important to do a little bit more effort on border control.”
Unlike other airports around the world, passengers arriving in the UK are not being screened by thermal imaging cameras looking for high body temperatures ‒ mainly because the technology will fail to detect a coronavirus infection nearly half the time and not pick up on passengers who are asymptomatic. Nonetheless, Heathrow Airport CEO John Holland-Kaye has called for an international standard in health screening similar to security checks on liquid and laptops. “It wouldn’t surprise me if this becomes a little bit like the liquids ban when it came in in 2006. At that time, that was when you had to take your laptop and liquids out of your bag. That was a big change in the way people travel. It helped keep people safe,” he told The Times on April 6.
The UK’s epidemic lags behind that of its close neighbours, which could work to its advantage as it will have had more time to prepare for subsequent infection waves and learn from other countries’ experiences that have started to lift lockdown measures and introduce new testing and surveillance programmes. But ultimately, the coronavirus pandemic doesn’t respect borders and tackling it will require a global, concerted effort. “Even if a single country like the UK could contain the spread within the country, there is always a risk of resurgence due to imported cases unless the global pandemic is over,” says Shibuya.
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