When Will Coronavirus Cases Peak In The UK?

R0, flattening the curve and why infections and deaths will peak at different times.

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The peak of the coronavirus outbreak in the UK is coming sooner than expected, Matt Hancock said on Friday, adding it would likely be here “in the next few weeks”.

Asked about reports that Britain could see a peak on April 12, Hancock told Sky News: “I defer to the scientists on the exact predictions – I’m not going to steer you away from that.

“That is one perfectly possible outcome.”

As confirmed cases worldwide topped 1,000,000 and deaths 50,000, this sounds like a sliver of good news in one the most turbulent of modern times.

But what does it actually mean, how is the prediction being made, and what will happen when we reach the peak?

HuffPost UK has the answers...

What is a peak?

The peak of the coronavirus outbreak will occur when the number of new infections each day stabilises and then falls.

Politicians such as Hancock rightly talk of the peak as a milestone in the fight against the pandemic but it’s important to realise that it will not be the end of the crisis.

Coronavirus Peak
Coronavirus Peak

How does an outbreak reach a peak?

There are currently two factors that contribute to the peak – social distancing measures and immunity, although the former is more important right now than the latter for a very simple reason.

“This is a new virus that the human race has not encountered previously, so nobody has any immunity to it,” Dr Peter English, a consultant in communicable disease control, tells HuffPost UK.

Every virus has something scientists call the “reproduction number”, shortened to R0 and pronounced “R naught”.

This is the average number of people one infected person will infect on. The R0 for coronavirus is around 2.5. “So you get a doubling roughly every five days in the number of cases,” says Dr English.

The R0 will be brought down over time by social distancing and the gradual spread of immunity as people get the virus and recover.

When R0 becomes 1, the number of new cases will plateau and as soon as it drop below one, even by a fraction, the new infection rates will drop.

According to Hancock, this plateau will come in the “in the next few weeks” and we should see a reduction shortly after but later on the same day, deputy chief medical officer Jonathan Van-Tam stressed it was too early to say for sure.

“We’ve always said that we will know if our social distancing measures are working a few weeks after we’ve put them in place,” he said.

Reiterating it was ’too soon to say”, he added: “It’ll partly depend upon how well those social distancing measures are adhered to by every one of us.

“I hope it will be soon. We’re going to watch very carefully to see when we’ve hit the peak and when we’re starting to turn it but we will not take any premature actions.”

NHS staff at a drive-through coronavirus testing facility.
NHS staff at a drive-through coronavirus testing facility.
Aaron Chown - PA Images via Getty Images

Peaking soon is good news, right?

Not necessarily. The “flattening of the curve” that the government has been talking about was never meant to reduce the number of people who contracted a potentially fatal case of coronavirus.

Professor Julian Peto, statistician and cancer epidemiologist at the London School of Hygiene and Tropical Medicine, told HuffPost UK: “They gave up on things like contact tracing very early on and started talking about ‘flattening the curve’, and flattening the curve just means that the actual peak is spread out so you don’t get an absolute catastrophe in the NHS.”

If the peak arrives earlier, but the same number of people contract Covid-19, then that peak will be higher, meaning more people needing treatment at the same time.

“The intention around the world is really more about protecting the health services because if we allow a very rapid rise in numbers you will very quickly overwhelm the health services,” Dr England adds.

Speaking at Friday’s government press briefing, Van-Tam addressed concerns that the NHS would not have enough ventilators to cope, saying: “I can tell you I don’t think we’re anywhere close to that kind of scenario at the moment.

“We will watch it extremely closely and we will make decisions as we need to on a day-by-day basis.”

Another factor to bear in mind is that, even when the infection rate peaks, the death rate will continue to rise.

“It’s usually about a week before you’re ill enough to be admitted to hospital and then another week until you actually die if it’s a fatal case,” Dr English explains.

“There will be a lag time and the death rate will still rise after the infection rate peaks.”

How do we actually know when the peak has been reached?

Testing, and that’s why everybody is talking so much about it right now.

Currently, the huge majority of tests are only being conducted in hospitals and people with mild symptoms of suspected coronavirus have been told to stay at home, meaning they are not being officially recorded at all.

Just testing in hospitals would still give us an indication of when we’ve hit the peak but a far more accurate picture could be drawn if it is increased.

Hancock has said the commitment to get to 250,000 tests a day – as set out by Boris Johnson – “still stands”, but he had wanted to “put a very clear timeline” on the goal to get to 100,000 by the end of the month.

What are they testing for?

This isn’t as straightforward as you might think as there are two types of test – antigen (using a method called PCR testing) and antibody.

Professor Matthew Freeman, head of Oxford’s Dunn School of Pathology, told HuffPost UK: “They answer two very different questions. One is ‘do I have the virus today?’ and the other one is ‘have I had the virus and am I immune to it?’”

The PCR test is looking for the actual virus itself while the antibody test is looking for signs that you have been infected in the past.

“When we get ill with viruses, we make an immune response to fight those viruses. That takes two or three days to come up but it then lasts,” Professor Freeman explains.

“That test is no use for testing if you have the virus now because it may be too early. There’s a lag of a few days, maybe even up to a week, before you get these antibodies.”

Why is it taking so long?

It’s certainly not for lack of potential resources.

“Every lab in Britain has dozens of PCR machines. They detect particular gene sequences in DNA and it can find one virus in a bucket of blood – they’re quite extraordinary,” says Professor Peto.

“The machines cost less than a £1,000 and everyone has loads of them. The point of it is that you can test on an absolutely colossal scale if you can get every lab in Britain to do it.

“What I’m talking about is doing 10m tests a day, because if you do 10m tests a day you can stop the epidemic, that’s the point.”

Professor Freeman shares this frustration but also acknowledges the logistical and bureaucratic challenge that an expansion of testing on such a scale presents.

“Imagine the complexity of it – you have to think about how you get the samples to you. Once they’re there, how do you handle them safely given that they’re potentially contaminated with the virus? How do you do the quality control and reporting of the testing? It really is logistically an incredibly complicated operation.

“My one message to the government is to be aware there is a willing, eager and able resource out there in the country and if we can be part of the solution, we’d really like to help.”

So should I go out and catch coronavirus so I can recover, be immune and get tested?

Absolutely not. It’s still a potentially fatal disease even for young people with no underlying health conditions. Additionally, the idea of immunity needs caveating as it is still a bit of an unknown at present.

“Part of the complexity is we don’t really know what sort of immunity you get after you’ve been infected with Covid-19. We know with measles for example, once you’ve been infected you’re extremely unlikely to get it again – you get good long-term immunity that protects you for the rest of your life,” Dr English says.

“With other coronaviruses – and there are four or so that are circulating and causing common colds and such all the time, and we’ve also seen Mers and Sars which are very closely related – the immunity you get doesn’t seem to last all that long.

“We just don’t know much about this coronavirus. With a bit of luck people will be immune for a year.”