Restrictions on social activities delay COVID-19 epidemic peak

These projections suggest that a premature and sudden lifting of the interventions put in place could lead to an earlier secondary peak of COVID-19, which could be ironed out by gradually easing the interventions.

In a study published in The Lancetresearchers examined how population mixing affected the progress of the coronavirus disease 2019 (COVID-19) outbreak in Wuhan, finding that if restrictions on activities were maintained until April, the epidemic peak would be probably delayed.1

These projections suggest that a premature and abrupt lifting of the interventions put in place could lead to an earlier secondary peak, which could be flattened by gradually easing the interventions.

“Non-pharmaceutical interventions based on sustained physical distancing have strong potential to reduce the magnitude of the COVID-19 epidemic peak and lead to a small number of overall cases,” the authors wrote. “Lowering and flattening the epidemic peak is particularly important, as it reduces the acute strain on the healthcare system.”

The researchers used location-specific synthetic contact models in Wuhan to examine changes in the population mix affected by the epidemic and adapted them in the presence of school closures, prolonged workplace closures and a reduction in admixture in the general population. They then simulated the ongoing trajectory of an outbreak in Wuhan using an age-structured susceptible-exposed-infected-removed (SEIR) model for several physical distancing measures.

In addition, the researchers fitted the latest epidemic parameter estimates from a transmission model to local and international exported case data from Wuhan in an age-structured epidemic framework and assessed the age distribution of cases. Simulations were also used to lift control measures by allowing people to return to work gradually and examined the effects of returning to work at different stages of the underlying epidemic (early March or April).

Projections indicated that physical distancing measures were more effective if the staggered return to work began in early April, reducing the median number of infections by more than 92% (IQR 66-97) and 24% (13-90) in mid-April. -2020 and late 2020, respectively.

According to the researchers, the benefits of maintaining these measures until April included delaying and reducing the height of the peak, the median size of the epidemic at the end of 2020 and giving health systems more time to develop and react. However, the researchers also indicated that the modeled effects of physical distancing measures vary depending on the duration of infectiousness and the role that school children play in the epidemic.

“While the precise effects of interventions may vary across countries and different estimates of key parameters, our model highlights the utility of physical distancing interventions and the need to carefully calibrate their lifting to avoid second and subsequent waves of distancing. ‘an outbreak of COVID-19,’ the authors wrote. “Policymakers are advised to reallocate their resources to focus on mitigating the effects of potentially overwhelmed health systems.”

The researchers indicated that they did not incorporate climatic factors into their mathematical model, and that future research should be directed towards understanding the possible seasonality of COVID-19 and the climatic factors that could affect its transmission dynamics. . Additionally, the extent to which various strategies can detect virus cases earlier and isolate infectious individuals from the susceptible pool or protect against infection is not well understood, which also requires further evaluation.

“As more and more data emerge to inform these and all relevant parameters that influence the transmission of this novel coronavirus, models can more accurately predict the success or failure of different strategies to control the outbreak. and limit mortality,” Tim Colbourn, PhD, associate professor of global health epidemiology and evaluation at the UCL Institute for Global Health, wrote in an editorial comment.2 “These models and projections should be made available in the public domain without delay to inspire public confidence and enable a potentially broader beneficial contribution. We need coordinated national and global efforts to quickly model solutions to the dire situation in which we currently find ourselves.


1. Prem K, Liu Y, Russell TW, et al. The effect of control strategies to reduce social mixing on the outcomes of the COVID-19 epidemic in Wuhan, China: a modeling study. The Lancet. doi:10.1016/S2468-2667(20)30073-6.

2. Colbourn T. COVID-19: extension or relaxation of remote control measures. The Lancet. doi:10.1016/S2468-2667(20)30072-4.

Joel C. Hicks