China appears to have “successfully exited [its] stringent social distancing policy” amid the coronavirus, scientists have said.
The previously-unknown strain is thought to have emerged at a seafood and live animal market in the city Wuhan, capital of Hubei province, at the end of last year.
“Strict social distancing” measures were put in place in Wuhan on 23 January, quickly followed by similar polices in other provinces.
At the peak of China’s outbreak, between 2,000 and 4,000 new cases were confirmed every day.
Up to 23 March, the country had no new “domestic” incidences for five consecutive days.
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This indicates social distancing measures have controlled the outbreak in China, the Imperial College London scientists claimed.
Once these were relaxed somewhat, the number of new cases remained reassuringly low.
“After very intense social distancing which resulted in containment, China has successfully exited [its] stringent social distancing policy to some degree”, said the scientists.
Since the outbreak was identified, cases have been confirmed in 170 countries across every inhabited continent.
More than 425,400 patients have been noted worldwide, of whom over 109,100 have “recovered” to date, according to John Hopkins University.
Cases have been plateauing in China since the end of February, with Europe now the epicentre of the pandemic.
The UK has had more than 8,100 confirmed cases and 422 deaths.
Globally, the death toll has exceeded 18,900.
‘China’s containment strategies are continuing to be effective’
The Imperial scientists measured the number of coronavirus cases arising daily in every province of mainland China.
“Within-city movement data” was collected between 1 January and 17 March for “major metropolitan cities”.
GPS tracking allowed the scientists to gauge the number of trips taken per person, compared to 2019.
The team then calculated the virus’ basic reproduction number, the number of people a patient statistically goes onto infect.
For example, a number of three means every patient is expected to pass the virus to three others.
This has proved tricky to calculate, with Professor David Heymann – from the London School of Hygiene & Tropical Medicine – previously telling Yahoo UK basic reproduction numbers “change daily as new information comes in”.
Nevertheless, the Imperial scientists found that as travel restrictions were put in place, inner-city movement declined alongside the coronavirus’ basic reproduction number.
Reassuringly, once these restrictions were relaxed somewhat, the basic reproduction number stayed low.
“These results provide evidence that China’s containment strategies are continuing to be effective as they restart their economy,” said the scientists.
Hubei, excluding Wuhan, lifted travel restrictions completely overnight. Wuhan will partially ease its measures on 8 April.
Many are worried about the coronavirus’ impact on the economy, with the FTSE 100 down 34.1% on 19 March.
Shutting borders worldwide has hit the travel industry hard, while draconian measures forcing Britons to stay in their homes has driven down spending.
Boris Johnson announced on Monday evening Britons are only to go outdoors to buy essentials, for exercise or if they are unable to work from home.
He previously urged the public to avoid social contact, ditch non-essential travel and work from home, if possible.
Different countries are at different stages of the pandemic, with the outbreak appearing to have peaked in China.
Its strategy may help “inform decision making processes for [other nations] once containment is achieved”, said the Imperial scientists.
The team stressed they only looked at confirmed cases. These are more likely to be severe, with many patients being diagnosed in hospital.
Early research suggests four out of five cases are mild, with most likely going undetected in the community.
Professor Brendan Wren from the London School of Hygiene & Tropical Medicine, said: “The latest data from Wuhan is encouraging and points the way to implementing strict social distancing measures in getting the epidemic under control.
“However, we still have no idea of the proportion of the population who are immunologically naïve to the virus and still susceptible to the potential re-emergence of the virus.
“A reliable antibody test to sample a large cross-section of the population for [the coronavirus] infection/carriage is a current global imperative.”
What is the coronavirus?
The coronavirus is one of seven strains of a class of viruses 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.
The coronavirus mainly spreads face-to-face via infected droplets that have been coughed or sneezed out.
While most cases are mild, pneumonia can come about if the infection spreads to the air sacs in the lungs, causing them to become inflamed and filled with fluid or pus.
The lungs then struggle to draw in air, resulting in reduced oxygen in the bloodstream and a build-up of carbon dioxide.
The coronavirus has no “set” treatment, with most patients’ immune systems fighting off the virus naturally.
In severe cases, hospitalisation may be required if a patient needs “supportive care”.
This may include ventilation while their immune system gets to work.