Effect of Predeparture Testing on Postarrival SARS-CoV-2–Positive Test Results Among International Travelers — CDC Traveler-Based Genomic Surveillance Program, Four U.S. Airports, March–September 2022

Demographic and travel characteristics and self‐reported predeparture SARS‐CoV‐2 testing behavior in air passengers entering the United States from foreign destinations from July to September 2021

“…Building on mathematical modeling studies estimating the effectiveness of layered mitigation measures on travel-related SARS-CoV-2 transmission, published evidence observed that rescission of mandatory predeparture testing in June 2022 was followed by an increase in post-arrival positivity in pooled samples of international air passengers arriving at Newark Liberty (EWR), John F. Kennedy International (JFK), Hartsfield-Jackson Atlanta (ATL), and San Francisco (SFO) international airports. 9 In this cross-sectional survey of international air passengers entering the US at six US POEs from July to September 2021, we investigated the association between certain passenger characteristics and their self-reported predeparture SARS-CoV-2 testing behaviors. We found that the type of viral test the passenger reported completing before departure was significantly associated with passengers' race and ethnicity, departure region, and test timing.…”

Challenges for COVID-19 surveillance through wastewater-based epidemiology in post-pandemic era: A retrospective study in 222 USA counties

“…For instance, before June 2022, limited personal movement was observed in USA in total air passengers with 12 M monthly average air passengers (including inbound and outbound passengers) 21 . In May and June 2022, the USA government began easing its travel restrictions on international passengers and removed the requirement of vaccination proof and mandatory negative testing result before boarding a ight to USA 22 , then the monthly average air passenger increased to 18 M and was close to the pre-pandemic levels (20 M) 21 . Such changes are clear signs of returning pre-pandemic lifestyles and the milestone of the start of the post-pandemic era, however, their impacts on the C RNA -Incidence correlation remain unknown.…”

“…USA government lifted the restrictions of negative testing results on international passengers before boarding a ight to USA after June 2022 22 , meaning that even positive visitors can freely enter USA. In a way, the periods before and after June 2022 resembles the pandemic period and post-pandemic period, respectively.…”

Genomic surveillance reveals dynamic shifts in the connectivity of COVID-19 epidemics

“…International travel restrictions, enacted by over 89 countries during the first five months of the pandemic [21], stand in contrast to recommendations by the World Health Organization, which argued against the use of travel restrictions and border closures due to their substantial economic, social, and ethical effects, and a lack of evidence on their effectiveness [22]. Although some travel restrictions-including complete border closures, quarantines, and testing requirements-have since been shown to reduce imported cases [17,[23][24][25][26], the relative contribution of imported cases on local cases before, during, and after restrictions is not fully understood. Additionally, connectivity across heavily-traveled and economically important land-borders, like the US-Mexico border, which was crossed 400 million times a year prior to the pandemic [27] and was closed to non-essential travel from March 19 th , 2020-November 8 th , 2021 [28,29] , remains unstudied.…”

“…International travel restrictions, enacted by over 89 countries during the first five months of the pandemic[21], stand in contrast to recommendations by the World Health Organization, which argued against the use of travel restrictions and border closures due to their substantial economic, social, and ethical effects, and a lack of evidence on their effectiveness[22]. Although some travel restrictions—including complete border closures, quarantines, and testing requirements—have since been shown to reduce imported cases[17,23–26], the relative contribution of imported cases on local cases before, during, and after restrictions is not fully understood. Additionally, connectivity across heavily-traveled and economically important land-borders, like the US-Mexico border, which was crossed 400 million times a year prior to the pandemic[27] and was closed to non-essential travel from March 19 th , 2020–November 8 th , 2021 [28,29], remains unstudied.…”