The authors were interested in the individual and combined effectiveness of self-imposed prevention measures against COVID-19 and how short-term government-imposed social distancing either mitigated, delayed or prevented outbreaks. They 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). Self-imposed measures were assumed to be taken by disease-aware individuals and these included hand-washing, mask-wearing and social distancing. Government-imposed social distancing reduced the contact rate of individuals irrespective of their disease or awareness status. The authors found that, for fast awareness spread in the population, self-imposed measures can significantly reduce the attack rate and diminish and postpone the peak number of diagnoses. A large epidemic could be prevented if the efficacy of these measures is >50%. For 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 alone delays but does not reduce the peak (by at most 7 months for a 3-month intervention). The delay can be longer and the height of the peak can be additionally reduced if this intervention is combined with self-imposed measures that are continued after government-imposed social distancing has been lifted. Therefore information dissemination about COVID-19, which leads to increased hand-washing, mask-wearing and social distancing, can be an effective strategy to mitigate and delay the epidemic. Early initiated short-term government-imposed social distancing can buy time for healthcare systems to prepare for an increasing disease burden.
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