Early in the COVID-19 pandemic, belated and strangely selective U.S. restrictions on international travelers created the appearance of doing something without having much of an impact on disease transmission. The Biden administration's response to the omicron variant has been notably swifter, but it still seems unlikely to work as advertised.
Last Wednesday, the South African government shared information about the omicron variant of the coronavirus, which features mutations that suggest it may be even more contagious than the delta variant. It is still not clear whether that is actually true, whether the new variant is more likely to cause severe symptoms, or whether vaccination is less effective against it than it is against earlier iterations of the virus, either in preventing infection or in preventing hospitalization and death.
Two days after news of the omicron variant broke, President Joe Biden announced a ban on visitors from South Africa and seven other African countries: Botswana, Eswatini, Lesotho, Malawi, Mozambique, Namibia, and Zimbabwe. With limited exceptions, noncitizens who were "physically present" in any of those countries during the previous 14 days will be denied entry to the United States and barred from U.S.-bound flights. The suspension will be reevaluated on a monthly basis to determine whether it is still appropriate.
The suspension did not take effect until this morning, which is the first clue that the policy is more symbolic than substantive. The travel ban "won't even start until Monday, as if the virus takes the weekend off," New York Times columnist Zeynep Tufekci noted yesterday. "That's pandemic theatrics, not public health."
Biden's proclamation does not apply to U.S. citizens or permanent residents. Legally, that makes sense, since the president is relying on his authority under Section 212(f) of the Immigration and Nationality Act, which applies to "aliens" whose entry he deems "detrimental to the interests of the United States." But if spending time in the countries targeted by Biden means someone may have been exposed to the omicron variant, that risk does not disappear simply because a potential carrier is a U.S. citizen or permanent resident. And if the risk can be managed through measures short of barring entry—such as testing and, where appropriate, isolation—why not apply those safeguards uniformly?
While existing PCR tests can distinguish between omicron and other variants, Biden's proclamation does not explicitly address screening of travelers, although it says the Centers for Disease Control and Prevention "shall implement other mitigation measures for travelers" departing for the U.S. from the eight specified countries "as needed." Under current regulations, U.S.-bound travelers who are not fully vaccinated must present a negative result from a viral test on a sample taken no more than a day before they travel. For fully vaccinated travelers, the sample can be taken up to three days before departure.
The geographic scope of Biden's proclamation is also questionable, since COVID-19 cases involving the omicron variant have been identified in many other places, including Australia, Belgium, Canada, Denmark, France, Germany, Hong Kong, Israel, Italy, the Netherlands, Portugal, and the U.K. "This could possibly be the tip of the iceberg," Dutch Health Minister Hugo de Jonge told reporters yesterday. NPR notes that "one of the identified cases of the omicron variant in Belgium had no contact or travel with any nations in southern Africa, suggesting community spread could already be taking place."
This is starting to look like a recapitulation of what happened at the beginning of the pandemic, when many countries imposed travel restrictions after the coronavirus already was spreading locally. According to modeling by researchers at Northeastern University, for instance, New York City may have had more than 10,000 COVID-19 infections by March 1, 2020, seeded primarily by European travelers. That was 10 days before then-President Donald Trump announced restrictions on travel from Europe. The prospect that Biden's reaction, although much faster, will be too little and too late to be effective seems especially likely if the omicron variant proves as contagious as scientists fear.
"There is very little utility [from] these kinds of bans," Saad Omer, director of the Yale Institute of Global Health, told NPR. "If the [aim] is to prevent the variant from coming in, it really doesn't make sense to exempt countries where it has been identified and that [have] even more direct flights than southern Africa….Unfortunately, from what we know about the epidemiology of SARS-CoV-2 and the epidemiology of this variant, the horse has probably left the barn."
Israel, Japan, and Morocco have responded to the new variant by banning all foreign visitors. Morocco's two-week ban includes citizens, while the other two countries are excluding foreign nationals. "Unvaccinated Israelis will have to self-quarantine for seven days," The New York Times reports, while "returning vaccinated Israelis will be tested upon landing and must self-quarantine for three days, pending results of another P.C.R. test." Australia said it was delaying a plan to resume the admission of international students, skilled migrants, and visitors from Japan and South Korea. Other governments are banning travelers from specific countries.
The World Health Organization (WHO), meanwhile, is warning that such restrictions could cause more harm than they prevent. "Travel restrictions may play a role in slightly reducing the spread of COVID-19 but place a heavy burden on lives and livelihoods," WHO's regional director for Africa, Matshidiso Moeti, said yesterday. "If restrictions are implemented, they should not be unnecessarily invasive or intrusive, and should be scientifically based."
Research on the effectiveness of international travel restrictions in curtailing the spread of COVID-19 and other contagious diseases has generated mixed results.
A review published by the Journal of Emergency Management in early 2020 found "minimal evidence" that travel bans decreased the spread of severe acute respiratory syndrome (SARS), Middle Eastern respiratory syndrome (MERS), Ebola, or Zika. The authors emphasized the "urgent need for additional research to inform policy decisions on the use of travel bans and other control measures."
An April 2020 study of COVID-19 published in Science found that "the travel quarantine of Wuhan delayed the overall epidemic progression by only 3 to 5 days in mainland China." According to the researchers' modeling, the quarantine "had a more marked effect on the international scale, where case importations were reduced by nearly 80% until mid-February." But the study indicated that the quarantine's impact was not sustained and that restrictions on travel to and from China did not have a large additional effect.
"The model indicates that although the Wuhan travel ban was initially effective at reducing international case importations, the number of imported cases outside mainland China will continue to grow after 2 to 3 weeks," the authors reported. "Furthermore, the modeling study shows that additional travel limitations (up to 90% of traffic) have only a modest effect unless paired with public health interventions and behavioral changes that can facilitate a considerable reduction in disease transmissibility."
A 2021 systematic review of 26 studies in BMJ Global Health found "a high level of agreement" that domestic travel restrictions in China "led to important changes in the dynamics of the early phases of the COVID-19 pandemic." Based on 13 studies of international restrictions, the authors concluded that limits on flights to and from China "may have led to additional reductions in the number of exported cases."
A 2021 BMC Public Health study based on data from Hong Kong concluded that "complete border closure"—a far cry from the current U.S. policy, but similar to what Morocco is now doing—"remained an effective measure" to reduce cases and deaths "even in the presence of established local transmission." Another study published this year in the same journal focused on Australia, which closed its borders to all nonresidents on March 20, 2020. "While travel bans lowered the number of COVID-19 importations overall," the researchers concluded, "the effectiveness of bans on individual countries varies widely and directly depends on the change in behaviour in returning residents and citizens."