Assessment of fever screening at airports in detecting domestic passengers infected with SARS-CoV-2, 2020-2022, Okinawa prefecture, Japan

Abstract

Background: While airport screening measures for COVID-19 infected passengers at international airports worldwide have been greatly relaxed, observational studies evaluating fever screening alone at airports remain scarce. The purpose of this study is to retrospectively assess the effectiveness of fever screening at airports in preventing the influx of COVID-19 infected persons.

Methods: We conducted a retrospective epidemiological analysis of fever screening implemented at 9 airports in Okinawa Prefecture from May 2020 to March 2022. The number of passengers covered during the same period was 9,003,616 arriving at 9 airports in Okinawa Prefecture and 5,712,983 departing passengers at Naha Airport. The capture rate was defined as the proportion of reported COVID-19 cases who would have passed through airport screening to the number of suspected cases through fever screening at the airport, and this calculation used passengers arriving at Naha Airport and surveillance data collected by Okinawa Prefecture between May 2020 and March 2021.

Results: From May 2020 to March 2021, 4.09 million people were reported to pass through airports in Okinawa. During the same period, at least 122 people with COVID-19 infection arrived at the airports in Okinawa, but only a 10 suspected cases were detected; therefore, the capture rate is estimated to be up to 8.2% (95% CI: 4.00-14.56%). Our result of a fever screening rate is 0.0002% (95%CI: 0.0003-0.0006%) (10 suspected cases /2,971,198 arriving passengers). The refusal rate of passengers detected by thermography who did not respond to temperature measurements was 0.70% (95% CI: 0.19-1.78%) (4 passengers/572 passengers).

Conclusions: This study revealed that airport screening based on thermography alone missed over 90% of COVID-19 infected cases, indicating that thermography screening may be ineffective as a border control measure. The fact that only 10 febrile cases were detected after screening approximately 3 million passengers suggests the need to introduce measures targeting asymptomatic infections, especially with long incubation periods. Therefore, other countermeasures, e.g. preboarding RT-PCR testing, are highly recommended during an epidemic satisfying World Health Organization (WHO) Public Health Emergency of International Concern (PHEIC) criteria with pathogen characteristics similar or exceeding SARS-CoV-2, especially when traveling to rural cities with limited medical resources.

Keywords: Airport; COVID-19; Fever screening; Prevention.

Fig. 1

Location of Okinawa Prefecture and nine airports conducted airport screening The nine airports participating in this study are illustrated by red dots: OKA: Naha Airport, MMY: Miyako Airport, ISG: Ishigaki Airport, UEO: Kumejima Airport, TRA: Tarama Airport, OGN: Yonaguni Airport, KTD: Kitadaito Airport, MMD: Minamidaito, SHI: Shimoji Airport The remaining airports are illustrated by pink dots

Fig. 2

Flow diagram of the airport screening for arriving passengers at Naha Airport All the arriving passengers were screened by thermography on arrival. Arriving passengers undergo a thermographic body temperature check as they exit the baggage claim area and enter the arrival gate. For follow-up, persons whose body temperature is detected by thermography are requested to take their temperature using a thermometer by the examiner. A thermometer will be used to determine if febrile or not. Febrile passengers are requested to provide individual information and to undergo diagnostic testing at the RT-PCR testing center adjacent to the airport

Fig. 3

Result of airport screening by thermography, may 2020 – march 2022, Okinawa prefecture, Japan (A) Thermographic detection rates for arriving passengers by airport (B) Thermographic detection rates on arrival and departure at Naha Airport

Fig. 4

– Result of airport screening by thermography on arrival and departure at Naha Airport stratified by month, may 2020 – march 2022, Okinawa prefecture, Japan (A) Thermographic detection rates for arriving passengers (B) Thermographic detection rates for departing passengers