Journal article

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The effect of control strategies to reduce social mixing on outcomes of the COVID-19 epidemic in Wuhan, China: a modelling study

Author(s): Prem K, Liu Y, Russell TW et al

Lancet Public Health 2020, Published Online March 25, 2020

Respiratory infections
Epidemiology
Public health

Digest Author(s): Stylianos Loukides, e-Learning Director / 29 March, 2020

In December, 2019, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a novel coronavirus, emerged in Wuhan, China. The COVID-19 pandemic significnatly changes the life of people living in the entire province of Hubei. Travel restrictions, physical distancing interventions, extended school closures and workplace distancing, were introduced to reduce the impact of the COVID-19 outbreak in Wuhan.

Which was the main purpose of the above restrictions? - To avoid crowded places and to change age-based mixing populations.

Using a specific model named SEIR, they divided the population according to the infection status into susceptible (S), exposed (E), infected (I), and removed (R) individuals and according to age into 5-year bands until age 70 years and a single category aged 75 and older (resulting in 16 age categories). They considered Wuhan as a closed system with a constant population size of 11 million. They also considered three different scenarios. The first one is based on no changes in social mixing, open schools and no Lunar New Year holidays. The second one assumes no interventions, winter school break in Wuhan, and Lunar New Year holidays. Finally, the third scenario is based on intense control measures.

The model based results showed that physical distancing measures were most effective if the staggered return to work was at the beginning of April. This could either influence the median number of infections by >90% or/and delayed the peak of epidemic. The authors finally suggest that premature and sudden lifting of interventions could lead to an earlier secondary peak, which could be flattened by relaxing the interventions gradually.

Comments

3 important points:

  • Early interventions based on schools could positively influence the peak of the pandemic and the number of infections.
  • Second and most important, any intervention decided by the national authorities is also targeting possible secondary peak of the disease.
  • Finally, the strict origin of the interventions is actually beneficial for the public health.