Airplane wastewater pilot shows how airports could track pathogens across borders

By Tarun Sai LomteReviewed by Susha Cheriyedath, M.Sc.Aug 4 2026

A bilateral US-UK pilot suggests airplane wastewater could help track pathogen movement through international travel, but broader airport coverage and standardized testing remain key.

Study: A bilateral US-UK airplane wastewater monitoring pilot demonstrates the feasibility of an international wastewater surveillance network. Unai Huizi Photography / Shutterstock

In a recent study published online as an 'Article in Press' in the journal Scientific Reports, researchers evaluated the feasibility of monitoring wastewater from airplanes at two connected international airports in the United Kingdom (UK) and the United States (US).

Wastewater-based epidemiology has been valuable for monitoring pathogens during the coronavirus disease 2019 (COVID-19) pandemic. International air travel can lead to rapid pathogen dissemination. As such, surveillance at travel hubs could serve as an early warning tool. Airplane wastewater sampling enables the detection of pathogen genetic material without involving travelers or disrupting airport operations.

Various countries implemented pathogen surveillance in airplane wastewater during the pandemic to identify and track emerging severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants. The US has, since 2021, operationalized traveler-based surveillance, collecting nasal samples from travelers and wastewater samples from airplanes to monitor the importation of variants and pathogens.

Likewise, the UK implemented SARS-CoV-2 surveillance in wastewater during the pandemic. This program also included a pilot study at UK airports that assessed the use of wastewater from wet wells, airplanes, vacuum trucks, and terminal sewers. It highlighted the complexity and utility of pathogen surveillance in this setting.

The Study and Findings

In the present study, researchers assessed the feasibility of airplane wastewater surveillance at international airports in the US and the UK. Wastewater samples were collected from flights operated by two airlines along a common transatlantic route between the two countries. One sample was collected per flight from the lavatory waste tanks during post-arrival servicing. UK-origin flights were sampled at the US airport between March 27, 2024, and January 16, 2025.

US-origin flights were sampled at the UK airport between July 22, 2024, and January 15, 2025. Pathogen testing was performed using digital polymerase chain reaction (dPCR) and quantitative polymerase chain reaction (qPCR) in the US and the UK, respectively. For qPCR, samples with any amplification were considered positive. For dPCR, samples with at least one positive partition were considered positive. All SARS-CoV-2-positive samples were further submitted for whole-genome sequencing, with genome recovery depending on viral concentration and sequencing coverage.

The study collected 308 wastewater samples from UK flights and 116 from US flights, respectively. Overall, 317 samples were positive for at least one of the targeted respiratory pathogens: SARS-CoV-2, influenza A virus, respiratory syncytial virus, or influenza B virus. Meanwhile, 303 were positive for at least one targeted enteric pathogen, adenovirus, norovirus GI, or norovirus GII. There were differences in pathogen detection proportions between US- and UK-origin flights, although direct comparisons were limited by differences in laboratory methods, assay sensitivity, and positivity thresholds.

Norovirus GII had the highest detection proportion on UK-origin flights, approximately 80%, followed by SARS-CoV-2 and norovirus GI. US-origin flights had lower detection rates, although these differences may partly reflect differences in analytical methods. Notably, influenza A virus detection was more frequent on flights originating in both countries at the end of 2024, in line with seasonality. dPCR results for SARS-CoV-2 were evaluated under a standard threshold, at least one positive partition, and a more stringent threshold, at least three positive partitions.

For samples positive under the standard threshold but negative under the stringent threshold, most (81%) produced sequencing data covering at least 25% of the SARS-CoV-2 genome at a minimum 10-fold depth. Notably, no SARS-CoV-2 sequences were recovered from the 64 sequenced samples that were negative under both thresholds. The researchers noted similar patterns in SARS-CoV-2 lineage frequencies in both directions, with KP.3.1.1 being the most common.

Nevertheless, UK-origin flights showed greater diversity of SARS-CoV-2 lineages, including LB.1 and JN.1.18, which were not detected on US-origin flights, although unequal sequencing coverage and sampling periods may have contributed to this difference. Notably, SARS-CoV-2 XEC, designated as a variant under monitoring on September 24, 2024, was detected four weeks earlier on UK-origin flights (from September 17, 2024) than on US-origin flights (from October 14, 2024).

Conclusions

In summary, the study provides proof-of-concept evidence that wastewater from airplanes can be collected and analyzed to enhance pathogen surveillance. However, the authors noted that the pilot involved only two connected airports and two airlines, used different laboratory methods, lacked field blanks, and could not estimate infection prevalence among all passengers because airplane wastewater reflects only lavatory users who shed detectable genetic material. Assay inhibition and residual tank waste were also not fully assessed. The recovery of SARS-CoV-2 Omicron lineages, LB.1 and JN.1.18, and the earlier detection of the SARS-CoV-2 XEC variant underscore that aviation wastewater sampling may help capture timely lineage movement.

Although the first clinical case of SARS-CoV-2 XEC in the US was recorded in July 2024, community and airplane wastewater data indicated that more substantial US transmission lagged until mid-October, highlighting the temporal sensitivity of airplane wastewater sampling. Overall, expanding airplane wastewater surveillance by covering additional airports, harmonizing assays, and enabling multilateral data sharing could improve early warning capabilities.