Stability of SARS-CoV-2 on Commercial Aircraft Interior Surfaces with Implications for Effective Control Measures.

BACKGROUND: The COVID-19 pandemic from 2019 to 2022 devastated many aspects of life and the economy, with the commercial aviation industry being no exception. One of the major concerns during the pandemic was the degree to which the internal aircraft environment contributed to virus transmission between humans and, in particular, the stability of SARS-CoV-2 on contact surfaces in the aircraft cabin interior. METHOD: In this study, the stability of various major strains of SARS-CoV-2 on interior aircraft surfaces was evaluated using the TCID50 assessment. RESULTS: In contrast to terrestrial materials, SARS-CoV-2 was naturally less stable on common contact points in the aircraft interior, and, over a 4 h time period, there was a 90% reduction in culturable virus. Antiviral and surface coatings were extremely effective at mitigating the persistence of the virus on surfaces; however, their benefit was diminished by regular cleaning and were ineffective after 56 days of regular use and cleaning. Finally, successive strains of SARS-CoV-2 have not evolved to be more resilient to survival on aircraft surfaces. CONCLUSIONS: We conclude that the mitigation strategies for SARS-CoV-2 on interior aircraft surfaces are more than sufficient, and epidemiological evidence over the past three years has not found that surface spread is a major route of transmission.

A global aircraft-based wastewater genomic surveillance network for early warning of future pandemics.

International airports can have a key role in screening, detecting, and mitigating cross-border transmission of SARS-CoV-2 and potentially other infectious diseases. With aircraft passengers representing a subpopulation of a country or region, aircraft-based wastewater surveillance can be a promising approach to effectively identifying emerging viruses, tracing their evolution, and mapping global spread with international flights. Therefore, we propose the development of a global aircraft-based wastewater genomic surveillance network, with the busiest international airports as central nodes and continuing air travel journeys as vectors. This surveillance programme requires routinely collecting aircraft wastewater samples for microbiological analysis and sequencing and linking the resulting data with associated international air traffic information. With the creation of a strong international alliance between the airline industry and health authorities, this surveillance network will potentially complement public health systems with a true early warning ability to inform decision making for new variants and future global health risks.

Does 2x2 airplane passenger contact tracing for infectious respiratory pathogens work? A systematic review of the evidence.

We critically appraised the literature regarding in-flight transmission of a range of respiratory infections to provide an evidence base for public health policies for contact tracing passengers, given the limited pathogen-specific data for SARS-CoV-2 currently available. Using PubMed, Web of Science, and other databases including preprints, we systematically reviewed evidence of in-flight transmission of infectious respiratory illnesses. A meta-analysis was conducted where total numbers of persons on board a specific flight was known, to calculate a pooled Attack Rate (AR) for a range of pathogens. The quality of the evidence provided was assessed using a bias assessment tool developed for in-flight transmission investigations of influenza which was modelled on the PRISMA statement and the Newcastle-Ottawa scale. We identified 103 publications detailing 165 flight investigations. Overall, 43.7% (72/165) of investigations provided evidence for in-flight transmission. H1N1 influenza A virus had the highest reported pooled attack rate per 100 persons (AR = 1.17), followed by SARS-CoV-2 (AR = 0.54) and SARS-CoV (AR = 0.32), Mycobacterium tuberculosis (TB, AR = 0.25), and measles virus (AR = 0.09). There was high heterogeneity in estimates between studies, except for TB. Of the 72 investigations that provided evidence for in-flight transmission, 27 investigations were assessed as having a high level of evidence, 23 as medium, and 22 as low. One third of the investigations that reported on proximity of cases showed transmission occurring beyond the 2x2 seating area. We suggest that for emerging pathogens, in the absence of pathogen-specific evidence, the 2x2 system should not be used for contact tracing. Instead, alternate contact tracing protocols and close contact definitions for enclosed areas, such as the same cabin on an aircraft or other forms of transport, should be considered as part of a whole of journey approach.

Prevalence of cataract among Australian commercial airline pilots.

Because little is known about cataract in pilots, we estimated prevalence by anonymously ascertaining all commercial airline pilots diagnosed with cataract 2011-2016 using the electronic Medical Records System of the Australian Civil Aviation Safety Authority. Of 14,163 Australian male commercial pilots licensed in 2011, 1286 aged ≥60 had biennial eye examinations showing a cataract prevalence of 11.6%. Among 12,877 pilots aged <60, based on compulsory eye examinations only when first licensed, prevalence was 0.5%. There was no significant difference by ambient ultraviolet (UV) radiation levels in state of residence though lowest prevalence was seen in the low-UV state of Victoria. Most cataract in pilots ≥60 years was bilateral and of mild severity, while cataract in pilots <60 were more likely to be unilateral and of greater severity.

Genomic Evidence of In-Flight SARS-CoV-2 Transmission, India to Australia, April 2021.

Epidemiologic and genomic investigation of SARS-CoV-2 infections associated with 2 repatriation flights from India to Australia in April 2021 indicated that 4 passengers transmitted SARS-CoV-2 to >11 other passengers. Results suggest transmission despite mandatory mask use and predeparture testing. For subsequent flights, predeparture quarantine and expanded predeparture testing were implemented.

Detection of the Omicron (B.1.1.529) variant of SARS-CoV-2 in aircraft wastewater.

On the 26th of November 2021, the World Health Organization (WHO) designated the newly detected B.1.1.529 lineage of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) the Omicron Variant of Concern (VOC). The genome of the Omicron VOC contains more than 50 mutations, many of which have been associated with increased transmissibility, differing disease severity, and potential to evade immune responses developed for previous VOCs such as Alpha and Delta. In the days since the designation of B.1.1.529 as a VOC, infections with the lineage have been reported in countries around the globe and many countries have implemented travel restrictions and increased border controls in response. We putatively detected the Omicron variant in an aircraft wastewater sample from a flight arriving to Darwin, Australia from Johannesburg, South Africa on the 25th of November 2021 via positive results on the CDC N1, CDC N2, and del(69-70) RT-qPCR assays per guidance from the WHO. The Australian Northern Territory Health Department detected one passenger onboard the flight who was infected with SARS-CoV-2, which was determined to be the Omicron VOC by sequencing of a nasopharyngeal swab sample. Subsequent sequencing of the aircraft wastewater sample using the ARTIC V3 protocol with Nanopore and ATOPlex confirmed the presence of the Omicron variant with a consensus genome that clustered with the B.1.1.529 BA.1 sub-lineage. Our detection and confirmation of a single onboard Omicron infection via aircraft wastewater further bolsters the important role that aircraft wastewater can play as an independent and unintrusive surveillance point for infectious diseases, particularly coronavirus disease 2019.

Wastewater surveillance demonstrates high predictive value for COVID-19 infection on board repatriation flights to Australia.

Controlling importation and transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from overseas travelers is essential for countries, such as Australia, New Zealand, and other island nations, that have adopted a suppression strategy to manage very low community transmission. Wastewater surveillance of SARS-CoV-2 RNA has emerged as a promising tool employed in public health response in many countries globally. This study aimed to establish whether the surveillance of aircraft wastewater can be used to provide an additional layer of information to augment individual clinical testing. Wastewater from 37 long-haul flights chartered to repatriate Australians was tested for the presence of SARS-CoV-2 RNA. Children 5 years or older on these flights tested negative for coronavirus disease 19 (COVID-19) (deep nasal and oropharyngeal reverse-transcription (RT)-PCR swab) 48 h before departure. All passengers underwent mandatory quarantine for 14-day post arrival in Howard Springs, NT, Australia. Wastewater from 24 (64.9 %) of the 37 flights tested positive for SARS-CoV-2 RNA. During the 14 day mandatory quarantine, clinical testing identified 112 cases of COVID-19. Surveillance for SARS-CoV-2 RNA in repatriation flight wastewater using pooled results from three RT-qPCR assays demonstrated a positive predictive value (PPV) of 87.5 %, a negative predictive value (NPV) of 76.9 % and 83.7% accuracy for COVID-19 cases during the post-arrival 14-day quarantine period. The study successfully demonstrates that the surveillance of wastewater from aircraft for SARS-CoV-2 can provide an additional and effective tool for informing the management of returning overseas travelers and for monitoring the importation of SARS CoV-2 and other clinically significant pathogens.

Detection of SARS-CoV-2 RNA in commercial passenger aircraft and cruise ship wastewater: a surveillance tool for assessing the presence of COVID-19 infected travellers.

BACKGROUND: Wastewater-based epidemiology (WBE) for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can be an important source of information for coronavirus disease 2019 (COVID-19) management during and after the pandemic. Currently, governments and transportation industries around the world are developing strategies to minimize SARS-CoV-2 transmission associated with resuming activity. This study investigated the possible use of SARS-CoV-2 RNA wastewater surveillance from airline and cruise ship sanitation systems and its potential use as a COVID-19 public health management tool. METHODS: Aircraft and cruise ship wastewater samples (n = 21) were tested for SARS-CoV-2 using two virus concentration methods, adsorption-extraction by electronegative membrane (n = 13) and ultrafiltration by Amicon (n = 8), and five assays using reverse-transcription quantitative polymerase chain reaction (RT-qPCR) and RT-droplet digital PCR (RT-ddPCR). Representative qPCR amplicons from positive samples were sequenced to confirm assay specificity. RESULTS: SARS-CoV-2 RNA was detected in samples from both aircraft and cruise ship wastewater; however concentrations were near the assay limit of detection. The analysis of multiple replicate samples and use of multiple RT-qPCR and/or RT-ddPCR assays increased detection sensitivity and minimized false-negative results. Representative qPCR amplicons were confirmed for the correct PCR product by sequencing. However, differences in sensitivity were observed among molecular assays and concentration methods. CONCLUSIONS: The study indicates that surveillance of wastewater from large transport vessels with their own sanitation systems has potential as a complementary data source to prioritize clinical testing and contact tracing among disembarking passengers. Importantly, sampling methods and molecular assays must be further optimized to maximize detection sensitivity. The potential for false negatives by both wastewater testing and clinical swab testing suggests that the two strategies could be employed together to maximize the probability of detecting SARS-CoV-2 infections amongst passengers.

Melanoma incidence in Australian commercial pilots, 2011-2016.

OBJECTIVES: Occupational exposure to cosmic and ultraviolet radiation may increase airline pilots' risk of cutaneous melanoma. Meta-analyses of available data show a higher than average incidence of melanoma in airline pilots, but the most recent systematic review revealed that few contemporary data are available. Moreover, all relevant studies have been conducted in Northern Hemisphere populations. We therefore aimed to examine if Australian commercial pilots have a raised incidence of melanoma compared with the general population. METHODS: We examined all melanoma histologically diagnosed among Australian-licensed commercial pilots in the period 2011-2016 by manually reviewing de-identified data in the medical records system of the Australian Civil Aviation Safety Authority. We estimated age-specific incidence rates and compared these with corresponding population rates using standardised incidence ratios (SIRs) as measures of relative risk. Expected numbers were calculated by multiplying age- and calendar period-specific person-years (PYs) with corresponding rates from the entire Australian population; 95% CI were calculated assuming a Poisson distribution of the observed cases. RESULTS: In this cohort of Australian-licensed commercial pilots observed for 91 370 PYs, 114 developed a melanoma (51 invasive, 63 in situ). More than 50% of melanomas occurred on the trunk, and the predominant subtype was superficial spreading melanoma. The SIR for invasive melanoma was 1.20 (95% CI 0.89 to 1.55) and for melanoma in situ, 1.39 (95% CI 1.08 to 1.78). CONCLUSION: Australian-licensed commercial pilots have a modestly raised risk of in situ melanoma but no elevation of invasive melanoma compared with the general population.

Frequency and clinical spectrum of in-flight medical incidents during domestic and international flights.

Most medical practitioners are not specifically trained to diagnose or manage in-flight medical incidents, yet there may occur a moral obligation to do so when least expected. We felt that knowledge of the frequency of emergency versus non-serious medical incidents, in addition to the clinical spectrum of incidents most often encountered, would be of interest to medical practitioners and, in particular, critical care physicians, who happen to find themselves asked to assist with such events. To this end we collaborated with the Department of Medical Services of a major Australian airline to define the incidence, severity, and type of all in-flight medical events encountered over the course of a year's flights. We audited in-flight medical data collected over a continuous 12-month period, which covered 131,890 international and domestic flight sectors transporting more than 27 million passengers. There was an average of 296 medical events per month (3555 in total) making the per-flight incidence of a medical event approximately 1:40 (2.7%). Of these in-flight incidents, 915 (26%) were graded as emergencies, with the commonest descriptors of such incidents being either loss of consciousness (37%) or a suspected cardiovascular event (12%). Six of these 915 emergencies proved fatal. Twenty-one flights were diverted due to medical incidents (<0.016% of all flights), with 52% of these attributed to suspected cardiac events. In this series, medical in-flight events were recorded in approximately one in 40 flights, whereas medical emergencies occurred in approximately one in 150 flights.