The draconian measures put in place by the UK government may have to last 18 months in order to stem the coronavirus outbreak, scientists from Imperial College London have predicted.
Boris Johnson has urged the public to avoid social contact, ditch non-essential travel and work from home, if possible.
Households where just one member has the tell-tale fever or cough have been told to self-isolate entirely for 14 days, not even venturing out to buy “food or essentials”.
While “social distancing” is key to keeping the most vulnerable safe, some worry the approach fails to build up immunity to the virus, leading to the possibility it may re-emerge once “lockdowns” are lifted.
A mathematical model by the Imperial College London scientists found the “suppression” approach – “reducing case numbers to low levels and maintaining that situation indefinitely” – is “preferred” over mitigation.
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Mitigation focuses on “slowing but not necessarily stopping epidemic spread” by protecting the elderly and already ill, who are most at-risk.
The “major challenge” of the suppression strategy, is it “will need to be maintained until a vaccine becomes available (potentially 18 months or more)”, the scientists wrote.
The new coronavirus strain is thought to have emerged at a seafood and live animal market in the Chinese city Wuhan, capital of Hubei province, at the end of last year.
It has since spread globally, with more than 182,000 people testing positive for the Covid-19 virus in over 150 countries across every inhabited continent.
Of these patients, more than 79,000 have “recovered” and are now testing negative for the strain.
While the outbreak began in China, cases have been plateauing since the end of February.
Europe is now the “epicentre” of the pandemic, with Italy alone having more than 27,900 confirmed cases and over 2,000 deaths.
More than 37,000 tests have been carried out in the UK, of which 1,553 have come back positive and 55 patients have died.
Globally, the death toll has exceeded 7,000.
Social contact limitations could be in place for up to 18 months
Scientists at Imperial used a simulation model “developed to support pandemic influenza planning”.
Many assumptions were made, including how long it takes for a patient to become infectious after catching the virus, how many people a patient statistically goes onto infect, and how many will ultimately die.
Based on this model, the experts concluded “suppression is the only viable strategy at the current time”.
“The social and economic effects of the measures which are needed to achieve this policy goal will be profound,” they added.
The team stressed it is “not at all certain that suppression will succeed long term”.
“No public health intervention with such disruptive effects on society has been previously attempted for such a long duration of time”, they wrote.
“How populations and societies will respond remains unclear.”
The Imperial scientists compared the Covid-19 virus to that which caused the Spanish flu pandemic of 1918.
With no vaccine available at the time, US cities responded by closing schools, churches, bars and other social venues.
Discouraging social contact could limit spread of Covid-19
Although initially successful at reducing case numbers, “transmission rebounded once controls were lifted”.
By discouraging social contact, the government hopes the Covid-19 virus will not spread as readily, with the outbreak eventually dying out.
The “challenge” is such interventions need to be maintained, “at least intermittently - for as long as the virus is circulating in the human population, or until a vaccine becomes available”.
“In the case of Covid-19, it will be at least a 12-18 months before a vaccine is available,” the scientists wrote.
“Furthermore, there is no guarantee initial vaccines will have high efficacy.”
The scientists stress there is “no easy policy decision to be made”.
While suppression has been successful to date in China, it “carries enormous social and economic costs which may themselves have significant impact on health and well-being in the short and longer-term”.
One expert praised the modelling but warned “very tough times [are] ahead”.
“Overall I think this is an excellent piece of work from some of the world’s best infectious disease modellers, and presents the models and policy options clearly,” said Dr Tim Colbourn, from University College London.
“The results are sobering though.
“Very tough times ahead as the policy option that reduces the most deaths involves school and university closures, and social distancing measures over 18 months for two-thirds of the time or more.
“This has never been tried anywhere ever – can it work?
“One clear message is the need to massively increase the number of [intensive care unit] beds in the NHS from the current 5,000.”
Dr Colbourn added it is of the “utmost importance” to know how the Imperial scientists will update their model as new information comes to light.
Dr Michael Head, from the University of Southampton, called Imperial’s model “important and useful”.
He added, however, “there are still huge uncertainties around any future estimates, reinforcing just how difficult decision-making is during a pandemic”.
For the most part, scientists welcomed the “seismic” measures put in place by Boris Johnson on Monday.
Social distancing ‘needs to happen now’
“I think the government have taken a step in the direction that is needed,” said Professor Alan McNally, from the University of Birmingham.
“There is no point in debating potential time lost and so on.
“It is clear social distancing needs to be happening now and [Monday’s] statements begin that process”.
Others added the UK is in this for the “long haul”.
“A key point is there is now a real possibility this will be a prolonged event, so the response needs to be sustainable; the measures we introduce must be ones that we can maintain for some time”, said Professor Mark Woolhouse, from the University of Edinburgh.
What is the coronavirus Covid-19?
The Covid-19 strain is one of seven of the coronavirus class that are known to infect humans.
Others include the common cold and severe acute respiratory syndrome (Sars), which killed 774 people during its 2002/3 outbreak.
Most of those who initially caught the Covid-19 virus worked at, or visited, the market in Wuhan.
The pathogen mainly spreads via infected droplets that have been coughed or sneezed out by a patient.
There is also evidence it may be transmitted in faeces and urine.
In most cases, a patient’s immune system naturally fights off the virus.
Pneumonia can come about when the infection causes the alveoli (air sacs) in the lungs to become inflamed and filled with fluid or pus.
The lungs then struggle to draw in air, resulting in reduced oxygen in the bloodstream.
Most patients do no require hospitalisation, with their immune system naturally fighting off the virus.
In severe cases, care is “supportive” – like ventilation – while the immune system gets to work.