Objectives: This study aimed to identify the incidence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection among fully vaccinated air travelers participating in an island-confined quarantine system (Phuket Sandbox Program). It also compared the differential risk of SARS-CoV-2 infection across different coronavirus disease 2019 (COVID-19) vaccines and the difference in time-to-detection periods between asymptomatic and symptomatic cases. Methods: This retrospective cohort study determined the cumulative incidence of SARS-CoV-2 infection among 63 052 air travelers who participated in a quarantine program from July 1, 2021 to October 31, 2021. Using Poisson regression with robust standard errors, we estimated the relative risk of SARS-CoV-2 infection across different brands and types of COVID-19 vaccines, adjusting for relevant covariates. We visualized the time-to-detection periods for SARS-CoV-2 infection using Kaplan-Meier failure curves and compared these curves for asymptomatic and symptomatic travelers using the log-rank test. Results: The overall incidence of SARS-CoV-2 infection was 0.3%. Individuals vaccinated with Ad26.COV2.S, Gam-COVID-Vac, CoronaVac, and replicating viral vector vaccines faced a significantly higher risk of infection than those who received the BNT162b2 and mRNA vaccines. The time-to-detection periods for asymptomatic and symptomatic cases did not differ significantly. Conclusions Despite the relatively low risk of SARS-CoV-2 infection, a risk of breakthrough cases remained with certain vaccines. Given the high proportion of asymptomatic cases, quarantine and intermittent testing should be implemented. The mandatory quarantine system proved effective in managing positive cases without necessitating a complete shutdown of travel. Implementing an island quarantine could be a viable strategy for reintroducing travel and tourism during a future COVID-19 outbreak or a new pandemic.

Objectives: This study aimed to validate the risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, identify infection risk factors among air passengers subject to a 14-day mandatory quarantine, and evaluate the accuracy of mass symptom-based screening criteria at an airport. Methods: This retrospective cohort study analyzed data from 116 004 air passengers who entered Thailand through Suvarnabhumi Airport in Bangkok from April 2020 to September 2020. The incidence of SARS-CoV-2 infection, risk characteristics, and accuracy indices of symptom-based screening were calculated. Results: The overall incidence of SARS-CoV-2 was 0.5%, or 540 infections per 100 000 air passengers. Identified risk factors included sex, nationality, continent of departure, on-arrival screening results, and month of travel. Positive screening results indicated a higher risk and positive likelihood ratio for SARS-CoV-2 infection. However, the on-arrival screening criteria demonstrated low sensitivity and area under the receiver operating characteristic curve. Conclusions The current study confirms previous findings that the risk of SARS-CoV-2 infection during air travel is low. However, this might result from strict pre-departure screening and the SARS-CoV-2 test requirement for arriving passengers. The symptom-based screening criteria used upon arrival showed a low probability of identifying positive cases, suggesting that incorporating additional criteria could help detect asymptomatic infections. The integrated screening and quarantine model proved effective in preventing the spread of the virus into local communities.

Objectives: This study aimed to identify the incidence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection among fully vaccinated air travelers participating in an island-confined quarantine system (Phuket Sandbox Program). It also compared the differential risk of SARS-CoV-2 infection across different coronavirus disease 2019 (COVID-19) vaccines and the difference in time-to-detection periods between asymptomatic and symptomatic cases. Methods: This retrospective cohort study determined the cumulative incidence of SARS-CoV-2 infection among 63 052 air travelers who participated in a quarantine program from July 1, 2021 to October 31, 2021. Using Poisson regression with robust standard errors, we estimated the relative risk of SARS-CoV-2 infection across different brands and types of COVID-19 vaccines, adjusting for relevant covariates. We visualized the time-to-detection periods for SARS-CoV-2 infection using Kaplan-Meier failure curves and compared these curves for asymptomatic and symptomatic travelers using the log-rank test. Results: The overall incidence of SARS-CoV-2 infection was 0.3%. Individuals vaccinated with Ad26.COV2.S, Gam-COVID-Vac, CoronaVac, and replicating viral vector vaccines faced a significantly higher risk of infection than those who received the BNT162b2 and mRNA vaccines. The time-to-detection periods for asymptomatic and symptomatic cases did not differ significantly. Conclusions Despite the relatively low risk of SARS-CoV-2 infection, a risk of breakthrough cases remained with certain vaccines. Given the high proportion of asymptomatic cases, quarantine and intermittent testing should be implemented. The mandatory quarantine system proved effective in managing positive cases without necessitating a complete shutdown of travel. Implementing an island quarantine could be a viable strategy for reintroducing travel and tourism during a future COVID-19 outbreak or a new pandemic.

Objectives: This study aimed to validate the risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, identify infection risk factors among air passengers subject to a 14-day mandatory quarantine, and evaluate the accuracy of mass symptom-based screening criteria at an airport. Methods: This retrospective cohort study analyzed data from 116 004 air passengers who entered Thailand through Suvarnabhumi Airport in Bangkok from April 2020 to September 2020. The incidence of SARS-CoV-2 infection, risk characteristics, and accuracy indices of symptom-based screening were calculated. Results: The overall incidence of SARS-CoV-2 was 0.5%, or 540 infections per 100 000 air passengers. Identified risk factors included sex, nationality, continent of departure, on-arrival screening results, and month of travel. Positive screening results indicated a higher risk and positive likelihood ratio for SARS-CoV-2 infection. However, the on-arrival screening criteria demonstrated low sensitivity and area under the receiver operating characteristic curve. Conclusions The current study confirms previous findings that the risk of SARS-CoV-2 infection during air travel is low. However, this might result from strict pre-departure screening and the SARS-CoV-2 test requirement for arriving passengers. The symptom-based screening criteria used upon arrival showed a low probability of identifying positive cases, suggesting that incorporating additional criteria could help detect asymptomatic infections. The integrated screening and quarantine model proved effective in preventing the spread of the virus into local communities.

Objectives: This study aimed to identify the incidence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection among fully vaccinated air travelers participating in an island-confined quarantine system (Phuket Sandbox Program). It also compared the differential risk of SARS-CoV-2 infection across different coronavirus disease 2019 (COVID-19) vaccines and the difference in time-to-detection periods between asymptomatic and symptomatic cases. Methods: This retrospective cohort study determined the cumulative incidence of SARS-CoV-2 infection among 63 052 air travelers who participated in a quarantine program from July 1, 2021 to October 31, 2021. Using Poisson regression with robust standard errors, we estimated the relative risk of SARS-CoV-2 infection across different brands and types of COVID-19 vaccines, adjusting for relevant covariates. We visualized the time-to-detection periods for SARS-CoV-2 infection using Kaplan-Meier failure curves and compared these curves for asymptomatic and symptomatic travelers using the log-rank test. Results: The overall incidence of SARS-CoV-2 infection was 0.3%. Individuals vaccinated with Ad26.COV2.S, Gam-COVID-Vac, CoronaVac, and replicating viral vector vaccines faced a significantly higher risk of infection than those who received the BNT162b2 and mRNA vaccines. The time-to-detection periods for asymptomatic and symptomatic cases did not differ significantly. Conclusions Despite the relatively low risk of SARS-CoV-2 infection, a risk of breakthrough cases remained with certain vaccines. Given the high proportion of asymptomatic cases, quarantine and intermittent testing should be implemented. The mandatory quarantine system proved effective in managing positive cases without necessitating a complete shutdown of travel. Implementing an island quarantine could be a viable strategy for reintroducing travel and tourism during a future COVID-19 outbreak or a new pandemic.

Objectives: This study aimed to validate the risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, identify infection risk factors among air passengers subject to a 14-day mandatory quarantine, and evaluate the accuracy of mass symptom-based screening criteria at an airport. Methods: This retrospective cohort study analyzed data from 116 004 air passengers who entered Thailand through Suvarnabhumi Airport in Bangkok from April 2020 to September 2020. The incidence of SARS-CoV-2 infection, risk characteristics, and accuracy indices of symptom-based screening were calculated. Results: The overall incidence of SARS-CoV-2 was 0.5%, or 540 infections per 100 000 air passengers. Identified risk factors included sex, nationality, continent of departure, on-arrival screening results, and month of travel. Positive screening results indicated a higher risk and positive likelihood ratio for SARS-CoV-2 infection. However, the on-arrival screening criteria demonstrated low sensitivity and area under the receiver operating characteristic curve. Conclusions The current study confirms previous findings that the risk of SARS-CoV-2 infection during air travel is low. However, this might result from strict pre-departure screening and the SARS-CoV-2 test requirement for arriving passengers. The symptom-based screening criteria used upon arrival showed a low probability of identifying positive cases, suggesting that incorporating additional criteria could help detect asymptomatic infections. The integrated screening and quarantine model proved effective in preventing the spread of the virus into local communities.