In a small trial, airplane sewage was found to be easy and useful for monitoring SARS-CoV-2 variants landing in the United States, the Centers for Disease Control and Prevention reported Thursday.
The study found that the tests could be done cheaply and easily; it added only about three extra minutes to aircraft maintenance times at airports and did not require harassing passengers with nasal swabs or other sampling methods. Additionally, testing could be easily scaled up as needed, as the world largely abandons other SARS-CoV-2 testing and surveillance strategies, the CDC authors concluded.
“This investigation demonstrated the feasibility of aircraft wastewater monitoring as a low-resource approach compared to individual testing to monitor SARS-CoV-2 variants without direct traveler involvement or disruption to airport operations,” concluded the authors.
The CDC conducted the study in collaboration with biotech company Ginkgo Bioworks. Together they collected and tested sewage samples from 80 flights to John F. Kennedy International Airport in New York between August 1 and September 9, 2022. All flights were international, originating from the UK , the Netherlands and France.
Overall, 65 airborne sewage samples from 80 flights (81%) tested positive for SARS-CoV-2. The rate of positive samples was the same in all three countries: samples from the Netherlands were 81% positive, with 22 out of 27 samples positive; France too, with 22 of the 27 positive samples; as did the UK, with 21 of 26 samples positive.
The researchers were able to obtain 27 genome sequences from 25 of the samples. All genomes revealed omicron sublines, mainly BA.5 as well as BA.4.6 and BA.2.75.
The study adds to other evidence that monitoring airport and aircraft wastewater can play a role in monitoring the spread of pathogens, such as SARS-CoV-2. And it’s part of the CDC’s broader pandemic-era efforts to integrate wastewater sampling into its pathogen surveillance systems.
This has proven useful in various locations across the country for monitoring early outbreaks of COVID-19 as well as tracking the spread of polio in New York. In the case of SARS-CoV-2, viral shedding in feces can start very early in an infection, potentially before a person shows symptoms.
There are limits to aircraft surveillance, of course. This will be especially useful for longer flights, where people are more likely to use the toilet. And it’s not clear if all airlines will accept sampling. Finally, since international travelers may have multiple connecting flights before arriving in the United States, it may not be possible to track the origin of variants arriving in the United States.
Still, the authors say surveillance has its place. “In combination with traveler-based surveillance, aircraft wastewater monitoring can provide a complementary early warning system for the detection of SARS-CoV-2 variants and other pathogens of public health concern. “