Airports' Covid-19 Screening: Methods And Effectiveness

In the wake of the COVID-19 pandemic, airports around the world have implemented various screening measures to prevent the spread of the virus. These include temperature checks, symptom screening, and questionnaires. While these measures may help reassure the public, their effectiveness in detecting infected travelers has been questioned. Studies suggest that airport screening may miss more than half of infected individuals due to the virus's incubation period and mild or asymptomatic cases. Nevertheless, screening can provide valuable time to implement other measures and raise public awareness about disease prevention. This article will explore the methods, effectiveness, and impact of airport screening procedures for COVID-19.

Screening methods include full-body infrared scanners, handheld infrared thermometers and ear gun thermometers

To detect signs of coronavirus-related fever, some countries have implemented temperature checks for incoming travellers. Screening methods include full-body infrared scanners, handheld infrared thermometers, and ear gun thermometers. Full-body infrared scanners measure skin temperature as a proxy for core body temperature. Handheld infrared thermometers and ear gun thermometers were previously used in West African airports during the 2014 Ebola crisis as a form of exit screening for those with 'unexplained febrile illnesses'.

While these screening methods can provide reassurance and help identify sick passengers, they have limitations and are not entirely accurate. They may flag passengers with different types of infections while missing those incubating the virus but not yet showing symptoms. This was evident during the SARS epidemic, where Canada's intensive border screening failed to detect any cases despite having 251 reported cases. Similarly, a CNN investigation found that the US had screened over 30,000 passengers without detecting any cases, some of whom later tested positive.

The effectiveness of airport screening is further challenged by factors such as the incubation period of the virus, which can be up to 14 days, and the presence of mild or asymptomatic cases. Additionally, screening during flu season can lead to false positives due to similar symptoms. While screening may not entirely prevent the spread of COVID-19, it can offer indirect benefits, such as gathering contact information and providing guidance to travellers.

Screening can help discourage ill travellers from travelling

While airport screening may help reassure the public, there is little evidence to suggest that these procedures are effective in preventing the spread of COVID-19. For instance, a CNN investigation revealed that the US authorities had screened more than 30,000 passengers by mid-February without detecting any cases. However, at least four of these passengers later fell ill with coronavirus.

Despite the limitations of airport screening, it can still help discourage ill travellers from travelling. Exit screening, which involves evaluating and quizzing passengers before they board planes, may prevent some who are sick or were exposed to a virus from travelling. For example, at least one New Zealander was prevented from boarding an evacuation flight from Wuhan, China, after failing a health check. Similarly, China has implemented exit screening at airports, pledging to "cooperate internationally to institute exit and entry screening with relevant regions suffering epidemics".

In addition to exit screening, entry screening can also play a role in discouraging ill travellers from boarding flights. Entry screening, conducted upon arrival at the destination airport, can be used to gather contact information that can be useful if an infection spreads during a flight. It also provides travellers with guidance on what to do if they become ill. For instance, the United States started entry screening of U.S. citizens, permanent residents, and their families who had been in China within the previous 14 days at 11 airports on 2 February 2020.

However, it is important to note that the effectiveness of airport screening is limited by the incubation period of COVID-19, which can range from 2 to 14 days. During this time, infected individuals may not exhibit any symptoms, making it challenging for screeners to detect the presence of the virus. As a result, even with exit and entry screening in place, there remains a risk of infected individuals slipping through the cracks and spreading the virus to others during travel.

Screening can help raise awareness and education about the spread of disease

While airport screening may not be the most effective method to prevent the spread of coronavirus, it can help raise awareness and education about the spread of the disease.

Airport screening can take many forms, from thermal scanning to symptom screening, and even full-body scanners. Thermal screening, in particular, has been criticised for its lack of effectiveness in detecting early signs of infection. For instance, during the SARS epidemic, Canada's intensive border screening failed to detect a single case. Similarly, the US authorities screened more than 30,000 passengers by mid-February without detecting any cases of coronavirus. However, at least four of those passengers later fell ill with the virus. This is due to the long incubation period of the virus, which can be as long as 14 days, during which infected individuals may not show any symptoms.

Despite these limitations, airport screening can still play a role in raising awareness and educating travellers about the spread of the disease. Screening measures can help identify travellers with common symptoms of infection, such as fever, cough, or respiratory difficulties. Health questionnaires are also often used to gather information about potential exposure to the virus, such as travel history and close contact with infected individuals. These measures can help travellers become more aware of the signs and symptoms of the disease, as well as the importance of monitoring their health and taking necessary precautions.

Additionally, airport screening can facilitate contact tracing efforts by gathering contact information from travellers, which can be useful if an infection is later detected on a flight. Screening measures can also provide an opportunity to educate travellers about the steps to take if they become ill, such as seeking medical attention and self-isolating. For example, China has implemented exit and entry screening at airports, with officials pledging to "cooperate internationally" in response to the epidemic.

While it is clear that airport screening alone cannot prevent the spread of coronavirus, it can be a valuable tool in raising awareness and educating travellers about the disease. By providing information and guidance to travellers, screening measures can help empower individuals to take responsibility for their own health and contribute to broader efforts to contain the spread of the virus.

Screening can provide valuable time to put in place other measures, such as distributing test kits

While airport screening for COVID-19 has been deemed ineffective by many experts, it can provide valuable time to put in place other measures, such as distributing test kits.

Airport screening methods for COVID-19 include full-body infrared scanners, handheld infrared thermometers, and ear gun thermometers. However, these methods have not proven entirely accurate. The issue is that they may flag passengers with a different type of infection while missing those who are incubating the virus but not yet showing symptoms. This was the case during the SARS epidemic, where Canada's intensive border screening failed to detect a single case despite having 251 infections. Similarly, a CNN investigation revealed that the US screened over 30,000 passengers without detecting any cases, four of whom later tested positive. A study from the London School of Hygiene and Tropical Medicine found that out of every 100 infected travellers on a 12-hour flight, 42 would go undetected through entry and exit screening, mainly due to the virus's incubation period.

Despite these limitations, airport screening can provide valuable time to implement additional measures. For example, during the initial stages of the COVID-19 outbreak, airport screening allowed time to distribute test kits and develop more targeted screening procedures. This was crucial as the outbreak grew, and more cases were identified. Additionally, exit screening, where passengers are evaluated before boarding, may prevent those who are sick or exposed to the virus from travelling. It also provides an opportunity to gather contact information, which is useful for contact tracing if an infection spreads during a flight.

While the effectiveness of airport screening in directly detecting COVID-19 cases is questionable, it can provide a window of opportunity to put in place more targeted measures. This includes distributing test kits to high-risk areas, conducting contact tracing, and implementing travel restrictions for regions with high infection rates. These additional measures, combined with the public reassurance that screening provides, can help slow the spread of the virus and protect vulnerable populations.

Screening may miss over half of people exposed to the virus

Airport screening for viruses has been found to miss at least half of infected travellers, according to a UCLA-led study. The researchers analysed screening for six viruses: the SARS coronavirus, the Ebola virus, the Middle East respiratory syndrome coronavirus, the Marburg virus, Influenza H1N1, and Influenza H7N9. They found that screening methods, such as thermal scanning and symptom screening, are particularly ineffective for diseases with long incubation periods, such as Marburg and Ebola. For example, Canada's intensive border screening during the SARS epidemic failed to detect any cases, despite having 251 reported cases in the country.

Similarly, a CNN investigation found that the US authorities had screened more than 30,000 passengers by mid-February without detecting any cases of coronavirus. However, at least four of these passengers later tested positive for the virus. A separate study from the London School of Hygiene and Tropical Medicine found that out of every 100 infected travellers on a 12-hour flight, 42 would go undetected through entry and exit screening. This is largely due to the long incubation period of the virus, which can be up to 14 days, and the fact that some cases are mild and may not show any symptoms.

The ineffectiveness of airport screening can be attributed to several factors. Firstly, thermal screening methods, such as infrared thermometers and full-body scanners, are not always accurate in detecting early signs of infection. Secondly, passenger questionnaires, which are used to assess exposure to infected individuals or risk factors, may not be effective if passengers do not answer honestly. For example, during the 2009 influenza pandemic, no more than 25% of passengers answered truthfully about their exposure to the virus.

To improve the effectiveness of airport screening, researchers suggest that those creating questionnaires understand the risk factors for each disease to better tailor the surveys. Additionally, studies should be conducted to quantify the use of fever-suppressing drugs by travellers and evaluate methods to encourage honest reporting. While airport screening may provide reassurance to the public, it is important to recognize that these procedures may not significantly impact the detection of infectious diseases.

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