Disease outbreaks and other matters of airline medical interest

From Airfinity’s curated analysis of various health and media sources and from the ECDC (European Centre for Disease Prevention and Control) Weekly Communicable Disease Threats Report:

  • The burden of COVID-19 has begun to decline in the US and across Europe, while increasing in Mexico as the COVID-19 winter wave continues.
  • JN.1 seems to be the current dominant variant in almost all G20 nations. Notable exceptions are Japan, South Korea and China, where JN.1 is rising but EG.5.1.1 remains dominant, and Russia, where XBB.1.16 is still dominant.
  • In December 2023, the WHO classified JN.1 as a Variant of Interest (VOI) due to its rapidly increasing spread. Current evidence, meanwhile, shows that the risk to public health from this strain at the global level is low. JN.1 is a sublineage of BA.2.86.1 and contains the L455S mutation in the spike protein, which is associated with very high immune escape but significantly attenuated infectivity. In vitro data suggest that vaccines are still effective against JN.1.
  • In most of Europe, rates of respiratory illness in the community remained elevated and at levels above baseline. Seasonal influenza is now circulating at higher levels than SARS-CoV-2 and respiratory syncytial virus (RSV).


  • Dengue has begun to surge in Peru, while Brazil has declared a public health emergency, given that dengue activity has nearly tripled compared to 2023. Brazil is set to begin the world's first national dengue vaccine campaign this month with a two-dose vaccination schedule for children aged 10 to 14 years.
  • Cases of cholera have continued to be reported in western, eastern and southern parts of Africa, some parts of the Middle East, South-East Asia and the Americas. The risk of cholera infection in travellers visiting those regions remains low.
  • Italy has reported an outbreak of mpox, while Victoria, Australia has reported its first case.

From the Canadian Centre for Health Protection of the Department of Health:

  • A case was reported on Jan 31st of one fatal case of co-infection with avian influenza A(H10N5) and influenza A(H3N2) in China’s Zhejiang province. The case involved a 63-year-old female with underlying medical problems, who first developed symptoms two months previously.  Importantly, her relevant close contacts did not show any abnormalities during the medical surveillance period. The risk of H10N5 virus infection in humans is low, and human-to-human transmission has not been observed.

Other  selected articles/publications of interest:

- Whereas at the beginning of the COVID-19 pandemic, viral load (hence, contagiousness) peaked at the start of symptoms, similarly to the flu, in the Omicron dominant era, SARS-Cov-2 viral load peaked on days 3-4. Practical takeaway: best to trust a rapid antigen test result from the third or fourth day of symptoms. https://academic.oup.com/cid/advance-article/doi/10.1093/cid/ciad582/7285011

- Yellow fever is endemic in 34 countries in Africa and in 13 countries in Central and South America. There is a risk of potential spread to non-endemic areas, such as in Asia, where Aedes aegypti, the vector responsible for most large urban outbreaks, is a threat. Vaccination remains the critical means of prevention and reducing related morbidity and mortality. There is more aggregated evidence suggesting that a single dose of yellow fever vaccine does provide lifelong protection in immunocompetent adults, especially those from non-endemic areas: https://www.thelancet.com/journals/langlo/article/PIIS2214-109X(23)00556-9/fulltext?dgcid=raven_jbs_aip_email

- An objective biomarker for depression could revolutionise diagnosis and help to improve early treatment. For aeromedical certification too it could be the breakthrough tool of the century. Could AI help us? In a study published in the Journal of the American Medical Association machine learning algorithms failed to find a depression biomarker: https://jamanetwork.com/journals/jama/fullarticle/2814702?guestAccessKey=42bf1ac1-c2fd-427a-af45-bd5cd8b0428e&utm_source=silverchair&utm_medium=email&utm_campaign=article_alert-jama&utm_content=olf&utm_term=013124&adv=000003448277

 - In another piece of eyebrow-raising science, these authors investigated whether human participants can gain volitional control of their arousal state using a pupil-based biofeedback approach. The findings are surprising and reveal “tremendous potential for translation to behavioural and clinical applications across various domains, including stress-related and anxiety disorders”. Not hard to imagine applications in aviation medicine. https://www.nature.com/articles/s41562-023-01729-z?utm_source=nathumbehav_etoc&utm_medium=email&utm_campaign=toc_41562_8_1&utm_content=20240126

 - Fainting is one of the commonest medical occurrences in passengers in-flight. We often know the immediate cause, like hyperventilation from anxiety, hunger, heat or standing for too long, but what is the ultimate mechanism of fainting? “Neurons in the brain are very much like extremely spoiled children. They need oxygen and they need sugar, and they need them now. They stop working very quickly if you deprive them of oxygen or glucose. These nerve cells begin to die after about 2–5 minutes without oxygen, but syncope typically lasts less than 60 seconds. If you add oxygen again, they’ll simply resume their work and do so just as quickly”. To better understand what happens inside the brain during syncope, researchers used electrodes to record the activity of thousands of neurons from various brain regions in mice as the animals fainted. Results reveal a mechanism involving a group of sensory neurons that connect the heart to the brainstem. This coordinated neural network apparently regulates fainting and recovery. The mystery remains, however, of how these neurons are triggered. https://www.nature.com/articles/d41586-023-03450-3?WT.ec_id=NATURE-202311&sap-outbound-id=EBBCBB1E4A9C565B90BA9D7D4D9D96E75F615913

- Challenges of Airline Medicine at the International Airline Medicine Association (IAMA) Scientific Meeting, May 4th, in Chicago, as usual on the Saturday before the start of the Aerospace Medical Association Annual Scientific Meeting. Soon more details about an exciting and relevant programme here:  https://iama-assn.org/

Dr Rui Pombal

IATA Medical Advisor