The following illustrates the concept of limiting the boom in cases to reduce the likelihood that health services will be overwhelmed (dashed red line) and there will be less unmet need for health services. This unmet need may include the inability to admit patients to a hospital or to provide critically ill inpatients with access to intensive care.
Interventions to reduce infection lead to longer but less acute epidemics. The slower evolution of the epidemic also provides time for health personnel to provide better care, for infected health workers to recover, for administrators to learn and adapt to the evolution of the situation, and for them to develop. vaccines and treatments. Although we have not validated this principle for COVID-19 epidemics, it is sufficiently validated in influenza simulations to consider it a reasonable assumption in response to this disease9.
We suggest that preventive application of low-cost interventions should be considered before detection, but with an imminent expectation of transmission to the community, because it may decrease both the total number of cases and their severity. This principle also applies to subregions of countries that have not yet detected cases of transmission in the community.
The basic reproductive number (R0) is the average number of secondary cases of an infectious disease that arise from cases in a totally vulnerable population, and reflects the epidemic potential of a pathogen10. R0 is a function of the number of contacts an infected person has, the risk of transmission by contact and the duration of infectivity.
Social distancing mainly acts on the first factor, by reducing the number of contacts each person has. Hygiene measures mainly act on the second factor, since they reduce the risk of transmission if contact occurs. There are epidemiological observations of the outbreak in China that would indicate the effectiveness of preventive application of the measures in the community.
The WHO-China Joint Mission on COVID-19 determined that widespread transmission and outbreaks in the community occurred in Wuhan prior to the application of comprehensive control measures4. However, in other parts of China, transmission in the community has been limited and most transmission has occurred in families. For example, of the 344 groups comprising 1,308 cases (out of a total of 1,836 reported cases) in Guangdong Province and Sichuan Province, between 78% and 85% have occurred in families4. This is probably due to the intense quarantine and social distancing measures applied in areas outside of Hubei before the establishment of widespread transmission in the community.