Quarantining of people infected with the new coronavirus and their family members is very effective in reducing the numer of COVID-19 diseases.
School closures plus quarantine comes second, while workplace distancing combined with quarantine is the third-most effective way.
The most effective way, though, to reduce the number of COVID-19 cases is to combine all three methods. These are the findings of the first-of-its-kind modelling study in Singapore, published in The Lancet Infectious Diseases journal.
The model
Using this model, authors estimated the cumulative number of SARS-CoV-2 infections at 80 days, after detection of 100 cases of community transmission. The study has its limitation since it was done in a simulated Singapore setting but it demonstrated that all the above-cited intervention scenarios were more effective at reducing cases than no intervention.
The study is the first of its kind to investigate using these options for early intervention in Singapore using simulation.
The authors note that despite heightened surveillance and isolation of individuals, suspected to have COVID-19 and confirmed cases, the risk is ongoing with the number of cases continuing to increase in Singapore.
Schools have not been closed, and workplace distancing is recommended, but it is not national policy (at least not till 23 March).
Dr Alex R Cook, National University of Singapore, said: “…the results of this study provide policy makers in Singapore and other countries with evidence to begin the implementation of enhanced outbreak control measures that could mitigate or reduce local transmission rates if deployed effectively and in a timely manner.”
In addition to a baseline scenario, which included no interventions, the authors proposed four intervention scenarios for implementation after failure of local containment:
- Isolation of infected individuals and quarantine of their family members (quarantine)
- Quarantine plus immediate school closure for 2 weeks
- Quarantine plus immediate workplace distancing, in which 50% of the workforce is encouraged to work from home for 2 weeks, and
- A combination of quarantine, immediate school closure, and workplace distancing.
These interventions follow some policy options currently being undertaken (quarantine and some workforce distancing) by the Singaporean Ministry of Health, as standard interventions for respiratory virus control.
Limitations
The authors note several limitations in their study, including dated census population data, impact of migrant movement, the impact of seeding of imported cases (transmissions originating from outside of Singapore), the dynamics of contact patterns between individuals, and other unforeseen factors.
Moreover, Joseph A Lewnard, University of California, Berkeley, USA, and Nathan C Lo, University of California, San Francisco, USA, cautions that although the scientific basis for these interventions might be robust, ethical considerations are multifaceted, political leaders must enact quarantine and social-distancing policies that do not bias against any population group.
Interventions, according to Lewnard, might pose risks of reduced income and even job loss, disproportionately affecting the most disadvantaged populations: policies to lessen such risks are urgently needed.
“Special attention should be given to protections for vulnerable populations, such as homeless, incarcerated, older, or disabled individuals, and undocumented migrants. Similarly, exceptions might be necessary for certain groups, including people who are reliant on ongoing medical treatment,” he concludes.
