An alternating cycle of suppression interventions and relaxation could offer a pragmatic strategy - particularly for developing countries - to prevent health systems from being overloaded while reducing the economical and societal burden.
The coronavirus pandemic has imposed an unprecedented challenge to global healthcare systems, societies and governments. SARS-CoV-2, which causes COVID-19, has been detected in almost every country in the world with 4.8 million confirmed cases and more than 300,000 deaths.
Since there are currently no effective treatments or a vaccine against COVID-19, the strategies to combat the pandemic globally concentrate on interventions that reduce the transmission of the virus through - sometimes drastic - measures of social distancing, including lockdowns. While such measures can prevent health systems from becoming overloaded, they can also lead to considerable economic costs, financial uncertainty and social problems in some countries. There is growing concern that such long-term interventions, particularly for developing countries, will not be sustainable. An alternative approach could be to alternate strengthened measures with periods of relaxation. However, it remains unclear how such intervals should look like such that the health systems of different countries will not become overloaded.
To address this question, an international team including researchers from the University of Bern modelled three scenarios for 16 countries - from India to Colombia - that differ in health care capacities and demography. Their results are now published in the European Journal of Epidemiology.
The first scenario modelled imposing no measures. As would be expected, the number of patients requiring intensive care would quickly exceed the available capacity significantly for every single country. Under this scenario, the duration of the epidemic would last nearly 200 days in the majority of the countries included and result in a vast number of deaths.
The second scenario modelled a rolling cycle of alternating cycle of 50-day mitigation measures followed by 30-day relaxation. Based on the considered parameters for the reproduction number R (the average number of people that are infected by one infected person), this strategy still be insufficient to keep the number of patients requiring healthcare below the available critical care capacity. After the first relaxation, the number of patients requiring intensive care units (ICUs) would exceed the hospital capacity and would result in a considerable number of deaths across the 16 countries. In this scenario, the pandemic would last approximately 12 months in high-income countries, and about 18 months or longer in the other settings.
As a final scenario, the researchers modelled a rolling cycle of 50-day suppression measures followed by 30-day relaxation. With such a strategy, the required number of ICUs remained within the national capacities for all countries. While this approach extends the duration of the epidemic beyond 18 months, a much smaller number of patients would die from COVID-19.
Oscar Franco, professor of epidemiology at the Institute of Social and Preventive Medicine (ISPM) at the University of Bern, summarizes: "Our study provides a strategic option that countries can use to help control COVID-19 and delay the peak rate of infections."
Measures that take into account the economy and society
The researchers highlight that their study mainly offers an illustrative comparison of different intervention strategies. There remains considerable uncertainty as to which measures will lead to a decrease or increase in new infections. Hence, the researchers highlight that the specific durations of these interventions would need to be defined by specific countries according to their needs and local facilities. The key is to identify a pattern that allows to protect the health of the population not only from COVID-19 but also from economic hardship and mental health issues.
"An intermittent combination of strict social distancing and a relaxation phase may allow populations and their national economies to ‘breathe’ at intervals - a potential that might make this solution more sustainable, especially in resource-poor regions", says Rajiv Chowdhury, global health epidemiologist at the University of Cambridge and lead author of the study.
Interfaculty collaboration at the University of Bern
The interdisciplinary research is also the result of a newly established collaboration between the ISPM and the Center for Space and Habitability (CSH) at the University of Bern. "This paper is an early demonstration of an unlikely realization we had several months ago: despite the stark differences in subject matter between epidemiology and astrophysics, the two disciplines draw upon the same foundation of methods including numerical modelling and statistics," says Kevin Heng, professor of astrophysics at the CSH. "Our intention is to build an interfaculty platform between the natural sciences and medicine on computational methods to further develop synergies between ISPM and CSH."
No option for Switzerland at the moment
A number of European countries are currently lifting the first measures after their lockdowns, including Switzerland. A broad testing strategy with intensified contact tracing will now be important to prevent another increase in infections. "Ideally, these additional measures will compensate for the lifting of previous measures in the long-term, such that the number of new infections will continue to stay at a low level without a major impact on the economy and society", says Christian Althaus, research group leader at the ISPM and co-author of the study. "Hence, cyclic intervention strategies are currently not being considered in Switzerland."
It remains to be seen whether this will be possible in all countries of the world. Until then, the cyclic strategies that are described in the study could offer a pragmatic solution - particularly for developing countries.
Chowdhury R, et al.: Dynamic interventions to control COVID-19 pandemic: a multivariate prediction modelling study comparing 16 worldwide countries. Eur J Epidemiol 2020. https://link.springer.com/article/10.1007/s10654-020-00649-w