Researchers in the United States have conducted a study highlighting the potential unintended consequences of implementing coronavirus disease 2019 (COVID-19) control policies in an inconsistent, patchy manner.
The study also highlights the importance of accommodating societal needs in a way that does not increase the risk of outbreaks becoming large epidemics.
Benjamin Muir Althouse (Institute for Disease Modeling, Bellevue) and fellow researchers from the University of Washington, University of Vermont, and Northeastern University say the findings are especially relevant, given the disorganized, scattered way in which the loosening of restrictions is being implemented in the United States.
A lack of coordination at the policy-level incentivizes people to seek out areas that are open to product purchase and service provision and to travel to public areas that can be accessed or places where religious services can be attended, explain Althouse, and team.
Such surges in inter-state mobility increase the distance people travel and the number of people clustering in certain areas.
“Therefore, scattered or disorganized reopening after lockdown could spark second waves of infection,” writes the team.
Care must be taken to avoid the unintended, negative consequences of implementing inconsistent epidemic control policies, say the researchers.
A pre-print version of the paper is available on the server medRxiv*, while the article undergoes peer review.
*Important notice: medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.
Non-pharmaceutical interventions in the US introduced in a scattered manner
While the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic raged on and infected millions of people, many countries introduced coordinated policies at the national level to try to control the transmission of the virus.
In the absence of any vaccine and effective treatments, non-pharmaceutical interventions such as social distancing, mask-wearing, stay-at-home policies, and restriction of group sizes have been shown to be effective at controlling transmission.
However, in many countries, particularly the United States, control measures were introduced in a patchwork, scattered manner, with many states, counties, and cities implementing self-isolation, school closures, and gathering restrictions independently.
Public places such as parks and trails have also been subject to inconsistent visitation patterns and closures, say Althouse and team.
“When some, but not all, parks and trails close, individuals may travel further to areas remaining open potentially seeding virus to previously uninfected areas,” they write.
“Taken together, the non-uniform implementation and relaxation of US state-level interventions have left the country with high numbers of cases and potential distrust of public health interventions.”
The researchers say the investigation of changing movement patterns and the impacts of inconsistent implementation of control interventions is needed to understand the transmission dynamics of SARS-CoV-2 properly.
What did the researchers do?
Now, Althouse and the team have examined real-time mobility and search data to investigate variations in gathering-specific behavior across the United States during the COVID-19 pandemic and then studied an epidemics model with partial gathering restrictions and only partial adoption of those restrictions.
The team found that while stay-at-home policies did reduce contacts across most of the country, certain activities and venues frequently saw increases in attendance. Throughout March, for example, between 10 and 30% of churches saw more people attend, even though church attendance had decreased overall across the nation.
This heterogeneity shows that venue closure can mean people seek out ones they can attend, even if it involves long-distance travel, say the researchers.
Indeed, the average distance traveled to churches during March increased by 13%, they add.
“Community tightness” is an important factor
The study found that the distance people traveled and the number of times they visited essential services correlated with “community tightness,” where tight communities are defined as those “with strong norms and little tolerance of deviance.”
The authors say that if the tightness level of a community is known, more targeted policy recommendations can be made.
For example, if a community has a large number of non-compliant individuals and lockdown cannot be fully implemented, it may be better to have no lockdown at all. Non-compliant individuals traveling to neighboring areas can create epidemics in areas where outbreaks would otherwise have been controlled.
Rather than completely closing churches, parks, and essential services, leaders could introduce measures that afford social distancing benefits, while balancing the mental health-associated costs of self-isolation, says the team.
“For example, more frequent services with fewer members could increase compliance with physical distancing,” suggest the researchers. “Without balancing the requirements of the intervention with the needs of the people, partial measures can be worse than no measures at all.”
Importantly, reopening more slowly would not necessarily be more effective, if it is carried out in an inconsistent manner, they add.
Implementation and relaxation must be consistent
The researchers say their study shows that non-pharmaceutical COVID-19 control measures must be implemented in a uniform, consistent way to avoid scenarios where introducing interventions is less effective than no intervention in the first place.
“Human behavior is a strong driver of the transmission dynamics of SARS-COV2 and care must be taken to reduce the heavy burden imposed by COVID-19 and avoid unintended, negative consequences from inconsistent policies around implementing and relaxing non-pharmaceutical interventions,” concludes the team.
*Important notice: medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.
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