It is estimated that approximately two thirds of COVID-19 cases exported from China between January 1 and 13 were not detected worldwide1. Most of these exported cases will be mild and will only be detected after several hundred cases appear and serious or fatal cases are recognized 5 to 8 weeks later, as has occurred in the recent COVID-19 outbreaks in Iran, South Korea, Italy and Seattle in the US US 2
The spread of transmission of the new coronavirus causing COVID-19 worldwide has been very rapid. The basic reproduction number is estimated between 2 and 33.4. The mode of transmission is believed to be infection by droplets and by contact, although it may be an opportunistic infection or it is transmitted by air when there is little distance between people4.
The transmission dynamics of the first cases of COVID-19 were considerably different from that of the SARS epidemic. In particular, the proportion of cases from healthcare centers was low and the proportion without known risk exposures was high4. Another important factor is that the viral load in nasopharyngeal and respiratory secretions is highest shortly after the onset of symptoms in COVID-19 cases5, compared to a maximum of around 10 days in SARS6 cases, making it more likely to be transmitted before accessing health care facilities.
Although the acquisition of knowledge regarding the dynamics of transmission is at an early stage, it is assumed that it will be necessary to gradually introduce rigorous measures to control this epidemic and highlight the importance of using early control in the community.
Quarantines, city “closures”, the complete closure of day-care centers, schools, universities and workplaces, as well as the cancellation of large-scale meetings and events, have a significant social and economic impact and are unlikely to be enforced until significant transmission is confirmed, when it may be less effective. However, there are a number of potentially cost-neutral, lower-ranking preventive interventions that could be considered when transmission is only suspected or anticipated. Here we analyze whether low-cost hygiene distancing and social distancing preventive measures should be implemented before confirming transmission in the community in countries with minimal or no confirmed person-to-person transmission of COVID-19.
The goal of preventive interventions is to curb the transmission of the disease and limit the impact on health services, especially in hospitals and intensive care units, to guarantee access to high-level care when necessary.
The concept of preventive deployment is based on the following assumptions that require further consideration and are detailed below: detallan a continuación:
- Preventive Deployment
Transmission of COVID-19 in the community can occur undetected or can only be recognized after containment is no longer viable.
- Implementation of the Intervention
Interventions implemented after transmission is detected in the community will be less effective.
- Intensity reduction
Reducing the intensity of infection, especially in the early stages, will delay the epidemic’s rise, reduce its intensity, extend cases for a longer time, and help limit the chances that critical care services will be overwhelmed. that could save lives7,8.
- Expected results of distancing and hygiene
Interventions for social distancing and hygiene improvement should:
a. decrease the total number of cases per week, but extend the duration of the epidemic;
b. decrease the severity of cases by reducing the viral inoculum.
Dalton CB1, Corbett SJ2, Katelaris AL3 1. Facultad de Medicina y Salud Pública, Universidad de Newcastle, Callaghan, NSW, Australia, 2308 2. Facultad de Salud de la Población y Facultad Clínica Occidental, Universidad de Sydney, Sydney, NSW, Australia, 2151 3. Centro Nacional de Epidemiología y Salud de la Población, Universidad Nacional de Australia, Canberra, ACT, Australia