Scientists have warned that the coronavirus outbreak “could easily resurge” when lockdown measures are relaxed.
Health experts around the world are beginning to hope we are entering the peak of the COVID-19 pandemic as stringent controls on public movement are introduced to reduce transmissions.
But some have warned Sky News that the downward slope of the outbreak brings with it new challenges for governments and populations that have been on lockdown.
There have now been around 1,500,000 confirmed cases of the coronavirus globally, and over 88,000 associated deaths. While many of these were in China, significant public health interventions there have managed to suppress transmissions.
However a new study from the University of Hong Kong focusing on these stringent social distancing restrictions in China has warned that when the control measures are relaxed a second wave could begin to spread.
Although China has been accused of under-reporting its total number of cases and deaths, the researchers stated that the government’s interventions have indeed “substantially reduced transmissibility of COVID-10 across the country”.
But they warn that when these interventions are lifted a second wave of transmission is possible because there is a lack of herd immunity to the disease – and the model they developed to show this could equally be used in the UK or any country which has introduced lockdown measures.
Professor Joseph T Wu from the University of Hong Kong, who co-led the research, said: “While these control measures appear to have reduced the number of infections to very low levels, without herd immunity against COVID-19, cases could easily resurge as businesses, factory operations and schools gradually resume and increase social mixing, particularly given the increasing risk of imported cases from overseas as COVID-19 continues to spread globally.”
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Dr David Nabarro, the World Health Organisation’s special envoy for the global response to COVID-19, told Sky News that recovering from the pandemic was “not just a case of removing lockdowns”.
“It’s also a case of communities everywhere being ready to be able to spot possible intrusions of COVID-19 into their midst and to be able to isolate people with the disease and to interrupt transmission.
“That capacity is going to be needed for the foreseeable future, because the virus isn’t going to go away. It’s going to stay with us for some time,” Dr Nabarro explained.
In the study in The Lancet, the researchers warn that if the virus was reintroduced to China, potentially from secondary epicentres such as Italy, Iran and the US, it could spread quickly again due to the gradual resumption of economic activities and normal levels of social mixing.
They suggest that taking an even more gradual approach to resuming economic activities is crucial and add that “continuous surveillance of the effect of social mixing and human mobility” on transmissions should be used to “tune socioeconomic activities accordingly”.
“Close monitoring of the instantaneous effective reproduction number and real-time tuning of policy interventions to ensure a manageable second wave remains the over-riding public health priority,” the academics reported.
Dr Nabarro said: “I’ve seen many examples of how in Europe the epidemic curve is beginning to plateau, but I want to stress it’s when you come down the downward slope that all the problems arise.
“I saw this in my work on Ebola. Because when people start to relax and think ‘Okay, I can go back to normal’, you get all sorts of difficulties.
“Suddenly new spikes of infection appear, and so I want to stress to everybody, it’s almost the most dangerous time when you feel you’re at the plateau and you think you can relax and restart.”