Travel Restrictions May Not Curb Coronavirus

Travel restrictions may have only a limited effect on containment of the novel coronavirus, if historical infectious outbreaks are anything to learn from, according to an “Ideas and Opinions” submission to the Annals of Internal Medicine.

Study authors from Dallas and Denver said that the coronavirus outbreak has surpassed the numbers of cases of historic outbreaks of infections such as SARS (2002-03), MERS (2012-13) or Ebola (2014). But one thing the outbreaks have in common is the significant impact on morbidity and mortality, disruptions in health care and availability of resources, and collateral economic and societal costs, the study authors wrote.

While the study authors note that public health strategists have focused on limiting travel and public gatherings such as school closures and city quarantines, past experience from other infections suggest that travel restrictions have a limited effect. They cited several examples:

• Travel restrictions decreased new influenza cases by 3% in a previous study. These restrictions delayed—but ultimately did not prevent–flu epidemics.
• Another study found travel bans only minimally controlled the spread of infectious diseases.
• A third study determined that by only identifying 5% of coronavirus infections, even a 99% reduction of travel may only ultimately reduce the epidemic outside of the Wuhan, China epicenter by no more than 24.9%.
• Speaking of China, some investigators estimate that a travel ban may only reduce the progression of an epidemic by 3 to 5 days due to the nearly 59,000 cases in Wuhan before a travel ban was put in place.
• One report suggests that nearly half of cases would be missed by airport screenings due to the long incubation period of the coronavirus. During the incubation period, a person may be permitted to fly, the study authors pointed out.

The study authors don’t believe that travel restrictions are enough to prevent transmission of coronavirus to new regions, but they offered other suggestions: aggressive patient screening, active contact tracing, and isolation. Early recognitions and early identification were important, but had the added effect on health care workers using more personal protective equipment and hang hygiene. Those measures were more effective than travel restrictions in preventing the spread: 46% reduction from hand hygiene, 77% reduction through the use of masks or respirators, and 32-33% reduction through gowns and gloves.

“Ebola, SARS, MERS, and coronavirus all have nonspecific clinical presentations, but each emerged in a specific geographic area, and the epidemiologic links to these regions were key in guiding clinicians to implement proper barrier protections and patient evaluation,” the study authors wrote. “This led public health agencies, including the World Health Organization and US Centers for Disease Control and Prevention, to recommend a systematic approach to patients presenting with a relevant exposure and symptoms of an acute respiratory viral infection, such as SARS or MERS.”

The study authors said that other factors may contribute to the rise of new novel infectious diseases, including climate change, increasing global travel, and evolving human/animal interface. Vital signs are the biggest clue to how quickly interventions need to be made, including temperature, heart rate, respiratory rate, and blood pressure.

“Given the increasing frequency of emerging infectious diseases that are geographically linked, is it time to add a ‘fifth vital sign’?” the study authors wondered. “A simple, targeted travel history can help us put symptoms of infection in context and trigger us to take a more detailed history, do appropriate testing, and rapidly implement protective measures.”

Electronic health records could sync with travel history to help health care workers make decisions about diagnoses and care for symptomatic returning travelers. Using training to gather travel history information — the same way health care providers are trained to ask for tobacco exposure to assess risks for cancer or heart disease–can be useful in detecting warnings sign that prompt protective action, they concluded.