Short quarantines as effective as travel bans

Graphic showing travelers wearing facemasks at an airport due to Covid-19.
Travelers wearing face masks due to COVID-19. (iStock)

When the pandemic coughed up the Omicron variant in late 2021, many governments responded with a familiar knee-jerk reaction: travel bans. Restricting travel may be an emotional balm for some, but these measures exert damaging social and economic tolls.

New research published in The Lancet Regional Health – Europe shows that there are better ways to mitigate the spread of COVID-19 and its viral variants while allowing travel between countries. University of Florida mathematician Burton Singer collaborated on the new research with a team from the Yale School of Public Health.

Public health experts agree that travel bans are ineffective at this stage of the pandemic because community transmission of COVID-19 is so entrenched globally. Yet, when new or poorly understood variants emerge, travel bans are sometimes viewed as politically tempting. This thinking will have to change as COVID is here to stay for the indefinite future.

The new research offers modeling evidence that short quarantines after travel, combined with testing upon leaving isolation, can effectively prevent a nation or region’s per capita infection rate from increasing compared to a full travel ban. The concept for this model stems from earlier work by this same group which found that quarantine times could be shortened from 14 or 10 days down to just 7 with a negative test upon exit from isolation.

The work modeled air travel between 26 paired origin-and-destination countries in Europe, using real-world data from November 21, 2021. They found that travel could be allowed between most pairings without increasing the per capita infection rates in the destination country when a reverse-transcriptase polymerase chain reaction test (re-PCRT) was performed on exit from quarantine.

“For nearly half of origin-destination country pairs analyzed, travel can be permitted in the absence of quarantine and testing,” said Singer, a faculty member of the UF Emerging Pathogen Institute. “For the majority of pairs requiring controls, a short quarantine with testing could be as effective as a complete travel ban. The estimated travel quarantine durations are substantially shorter than those specified for traced contacts.”

The underlying logic is that if infection rates are similar between the origin and destination countries, then there is no increase in risk of transmission to citizens of the destination country if the public health measures between the two countries are the same.

The team also evaluated the role of travel volume and direction on quarantine and testing strategies, the role of variants of concern such as delta and omicron, and age-specific vaccination status.

The new model addresses a meaningful gap for the travel industry: no one had previously studied the necessary quarantine length after travel to prevent a per capita infection rate increase in the destination countries.

“Knowing what the minimum quarantine period should be normalizes travel and somewhat removes the stigma of travelers bringing disease with them,” Singer said. “This is very important for areas that have been economically damaged from lost tourism revenue.”

The team cautions that the model applies only when an infectious agent is already widespread globally. Border closures can be effective at slowing the spread of disease at much earlier stages, they write. And as the nature of the pandemic changes and settles into being here with us indefinitely, quarantine strategies will need to be revised and adapted for new contexts.

“This shows that there is no one right solution to the issue of travel restrictions, quarantines, and testing,” Singer said. “These decisions need to be rooted in context and evidence. But we’ve shown that travel can be done safely, and there is a thoughtful way to reduce the social and economic toll of travel restrictions.”

By: DeLene Beeland