Written by: Saradha Miriyala
Edited by: Yevin Chung
There is no question that coronavirus (COVID-19) has caused a widespread panic across the world. With cases appearing far from Wuhan, China (the site of origin), countries are scrambling to keep the disease out of their borders via airport screenings, quarantines, and travel warnings for those travelling to Asia. However, despite these measures, cases of COVID-19 have appeared in the United States, Iran, Italy, and South Korea . With extensive screenings both domestically in China and internationally for those travelling from these regions, why has COVID-19 been able to spread? The answer lies in the nature of the screenings themselves.
The history of infectious disease screening stretches back to the plague epidemic of 1347–1352 as it spread through ship trade from Italy, and then France and Spain. As Europe observed the powerful city states of Florence, Venice, and Genoa being decimated by the plague, they began fearing for their welfare and began banning minority groups, goods from infected countries, and ships from “unclean” ports. Within these countries, patients exhibiting plague symptoms were also quarantined into plague hospitals called lazarettos in remote locations . But as history shows, none of these efforts were enough to stop the devastation of the plague from ravaging Europe.
More than 600 years have passed since the plague, but the current method of preventing the import of the disease is still very similar. According to a White House proclamation on COVID-19, visitors are now barred from entering if they were “ physically present within the People’s Republic of China, excluding the Special Administrative Regions of Hong Kong and Macau, during the 14-day period preceding their entry or attempted entry into the United States” . If the first condition is met, upon arrival, passengers at one of the twenty airports conducting screenings are checked for symptoms of the virus at quarantine stations staffed by the CDC (Center for Disease Control) . In the event that patients exhibit any of the symptoms of the virus during the check, including a fever, cough, or shortness of breath, they are either admitted into hospitals or placed into quarantined home stays [1,5].
While airport screenings and travel restrictions are helpful and played a major role in containing the SARS (Severe acute respiratory syndrome) of 2003 and the Ebola outbreak in 2014, they are not foolproof. According to Jamie Lloyd Smith, an infectious disease ecologist at UCLA, “Travelers screening is not some kind of firewall that will absolutely protect from having cases imported … this is not because [the screening] is being done poorly, and it’s not because the people who are in charge are being lazy” [1,2]
The first reason that airport screenings cannot easily detect COVID-19 is because the symptoms are so latent. People infected with the virus may not even display symptoms until weeks after . Therefore, travelers that are seemingly healthy upon arrival and have satisfied all the necessary requirements for entry may actually be carrying the disease. Even with multiple screenings, about 42 percent of people with COVID-19 are entering the country . Furthermore, the methods that are used to detect symptoms can yield false negative results. For example, the temperature guns used to detect fevers at customs and border checkpoints are only 70 percent accurate. This means that a fourth of people with fevers are going unnoticed. Patients may also take over the counter fever medication in the event of a fever, unaware that they may carry the virus, and this cannot be detected during a screening .
To combat this discrepancy, Lloyd Smith has teamed up with other scientists to analyze the strengths and weaknesses of screenings and is trying to create a process that systematically evaluates the effectiveness of screenings. This process takes several factors into account, including the failure rates of fever detection, the various ways viruses move between people, and the accuracy with which people report their symptoms on questionnaires, among many others .
While it is impossible to use screenings to completely shut COVID-19 out of the United States, enhanced screening provides a positive prognosis for the future. Through Lloyd Smith’s methods, health professionals can catch between 20 and 50 percent of infected travelers, which slows the spread of the disease and gives health professionals time to coordinate responses and improve their protocol .