Podcast: Does quarantine, alone or in combination with other public health measures, control coronavirus (COVID-19)?

COVID-19 has spread quickly throughout the world, and Cochrane is maintaining a series of rapid reviews of the evidence to help decision makers respond to the pandemic. In this podcast, lead author, Barbara Nussbaumer-Streit from Danube University Krems in Austria outlines the findings of the review of quarantine, which was originally requested by the World Health Organization and was first published in April, before being updated in September 2020.

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Monaz: Hello, I'm Monaz Mehta, editor in the Cochrane Editorial and Methods department. COVID-19 has spread quickly throughout the world, and Cochrane is maintaining a series of rapid reviews of the evidence to help decision makers respond to the pandemic. In this podcast, lead author, Barbara Nussbaumer-Streit from Danube University Krems in Austria outlines the findings of the review of quarantine, which was originally requested by the World Health Organization and was first published in April, before being updated in September 2020.

Barbara: Most people with COVID-19 suffer only mild, flu-like symptoms; but some become seriously ill, and some die. Non-medical public health interventions are needed to help control its spread and one strategy is for people who are at high risk of having COVID-19, to remain in quarantine.
We did our review to see if this helps prevent the spread of the virus and save lives. We also wanted to know the costs of quarantine and whether it was more effective when combined with other measures, such as physical distancing. After publishing the initial version of the review in early April, 22 additional studies on quarantine for COVID-19 have become available. While the number of studies has increased significantly in a short space of time, the evidence base is still limited because most of the studies use mathematical modelling, rather than real world settings, and make different assumptions for the important model parameters. Jumping to our conclusions, the evidence suggests that implementation of quarantine early on in a pandemic and combining quarantine with other public health measures can help slow the spread of COVID-19.  However, it is difficult to determine what combination of measures is best for reducing the number of cases and deaths.
To get answers as quickly as possible in these COVID-19 rapid reviews, we have shortened some of the steps of the normal Cochrane Review process, but we still searched very widely for relevant studies. We included non-randomized studies of interventions and modeling studies on quarantine alone or in combination with other public health measures to control COVID-19, or earlier coronavirus-diseases, such as severe acute respiratory syndrome, known as SARS, and Middle East respiratory syndrome, which shortens to MERS.
Our September 2020 update includes 51 studies. There are four observational studies and 28 modelling studies on COVID-19, and four observational and 15 modeling studies on SARS and MERS.
The modeling studies consistently reported a benefit of the simulated quarantine measures. For example, the models estimated that quarantine of people exposed to confirmed or suspected cases of COVID-19 prevented between 44% and 96% of the cases that would otherwise have happened and 31% to 76% of the deaths, when compared to no such measures. The range of values reflects the different scenarios in the models. In regard to costs, the earlier the quarantine measures are implemented, the greater the cost savings will be.
The modeling studies also suggest that when quarantine is combined with other prevention and control measures, such as school closures, travel restrictions and physical distancing, there is an even greater effect on the reduction of new cases, transmissions and deaths.
However, our confidence in the evidence remains very limited. This is mainly because most of the research on COVID-19 and quarantine are mathematical modelling studies that make different assumptions on important model parameters and the few observational studies have methodological issues, such as lacking a control group.
In summary, despite the limited evidence, all the studies found quarantine to be essential for controlling the spread of severe coronavirus diseases. Early implementation of quarantine and combining quarantine with other public health measures is important to ensure effectiveness. Looking to the future, in order to maintain the best possible balance of measures, decision makers must continue to constantly monitor the outbreak situation and the impact of the measures they implement.

Monaz: If you would like to read the full review, it’s available free online. Just go to Cochrane Library dot com and search 'COVID-19 and quarantine'.

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