Transient immune impairment after a simulated long-haul flight

Annelies Wilder-Smith, Fatima B. Mustafa, Chung Mien Peng, Arul Earnest, David B C Koh, Gen Lin, Mohammed Iqbal Hossain, Paul A. Macary

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8 Citations (Scopus)


Introduction: Almost 2 billion people travel aboard commercial airlines every year, with about 20% developing symptoms of the common cold within 1 wk after air travel. We hypothesize that hypobaric hypoxic conditions associated with air travel may contribute to immune impairment. Methods: We studied the effects of hypobaric hypoxic conditions during a simulated flight at 8000 ft (2438 m) cruising altitude on immune and stress markers in 52 healthy volunteers (mean age 31) before and on days 1, 4, and 7 after the flight. We did a cohort study using a generalized estimating equation to examine the differences in the repeated measures. Results: Our findings show that the hypobaric hypoxic conditions of a 10-h overnight simulation flight are not associated with severe immune impairment or abnormal IgA or cortisol levels, but with transient impairment in some parameters: we observed a transient decrease in lymphocyte proliferative responses combined with an upregulation in CD69 and CD14 cells and a decrease in HLA-DR in the immediate days following the simulated flight that normalized by day 7 in most instances. Discussion: These transient immune changes may contribute to an increased susceptibility to respiratory infections commonly seen after long-haul flights.

Original languageEnglish
Pages (from-to)418-423
Number of pages6
JournalAviation Space and Environmental Medicine
Issue number4
Publication statusPublished - Apr 2012
Externally publishedYes


  • Air travel
  • Common cold
  • Immune markers
  • Respiratory infections
  • Stress markers

Cite this

Wilder-Smith, A., Mustafa, F. B., Peng, C. M., Earnest, A., Koh, D. B. C., Lin, G., Hossain, M. I., & Macary, P. A. (2012). Transient immune impairment after a simulated long-haul flight. Aviation Space and Environmental Medicine, 83(4), 418-423.