A modelling study performed at UMC Utrecht indicates that self-imposed prevention measures (handwashing, wearing face masks, social distancing) as well as governmental interventions (e.g. closure of restaurants and bars, cancellation of mass events) may significantly contribute to tackling the spread of COVID-19. Increasing disease awareness among the general public is essential for controlling the ongoing pandemic and preventing a 2^nd wave of infections.

COVID-19 caused by SARS-CoV-2 has spread globally since it first emerged in China in December 2019. Many countries have implemented social distancing as a measure to 'flatten the curve' of the pandemic. Evaluation of the impact of government-imposed social distancing and of other measures to control further spread of the virus is urgent, especially because of their huge societal and economic impact. Investigators of the mathematical modelling group led by Prof. Mirjam Kretzschmar at the Julius Center for Health Sciences and Primary Care at UMC Utrecht therefore compared the efficacy of self-imposed prevention measures and of short-term government-imposed social distancing in mitigating, delaying, or preventing a COVID-19 epidemic.

Measures and interventions

The investigators developed a deterministic compartmental transmission model of SARS-CoV-2 in a population stratified by disease status (susceptible, exposed, infectious with mild or severe disease, diagnosed and recovered) and disease awareness status (aware and unaware) due to the spread of COVID-19. Self-imposed measures were assumed to be taken by disease-aware individuals and included handwashing, mask-wearing, and social distancing. Government-imposed social distancing reduced the contact rate of individuals irrespective of their disease or awareness status. The model was parameterized using current best estimates of key epidemiological parameters from COVID-19 clinical studies. The model outcomes included the peak number of diagnoses, attack rate, and time until the peak number of diagnoses.

Disease awareness is crucial

“For fast awareness spread in the population, self-imposed measures (in particular a combination of measures such as self-imposed social distancing and mask-wearing) can significantly reduce the attack rate, and diminish and postpone the peak number of COVID-19 diagnoses”, says dr. Alexandra Teslya, first author of the manuscript. “In case of slow awareness spread, self-imposed measures reduce the peak number of diagnoses and attack rate but do not affect the timing of the peak. Early implementation of short-term government-imposed social distancing can only delay the peak (by at most 7 months for a 3-month intervention). The delay can be even longer and the height of the peak can be additionally reduced if such governmental intervention is combined with self-imposed measures that are continued after government-imposed social distancing has been lifted.”

Continue self-imposed measures

Co-investigator dr. Ganna Rozhnova concludes: “The results of our modelling study suggest that effective dissemination of public health information about COVID-19 that causes individual adoption of handwashing, mask-wearing and social distancing can be effective to mitigate and delay the epidemic. In addition, early-initiated short-term government-imposed social distancing can buy time for healthcare systems to prepare for an increasing COVID-19 burden. We stress the importance of disease awareness among the general public for controlling the ongoing pandemic and preventing a 2^nd wave of infections. Therefore, we recommend that, in addition to policies on social distancing, governments and public health institutions mobilize people to continue to adopt self-imposed measures with proven efficacy in order to successfully tackle the COVID-19 pandemic.”

Publication

Teslya A, Pham TM, Godijk NG, Kretzschmar ME, Bootsma MCJ, Rozhnova G. Impact of self-imposed prevention measures and short-term government intervention on mitigating and delaying a COVID-19 epidemic. PLOS Medicine 2020;17(7):e1003166.