Chris Del Mar and Peter Collignon: Another seasonal influenza epidemic

Healthcare staff are being urged to get flu jabs, but are current management options adequate?


Public health physicians and clinicians keep a wary eye out for epidemics of influenza, bearing in mind the greatest pandemic at the end of the first world war, when tens of millions died. [1] Influenza epidemics come every year, but their severity varies from year to year. Normally influenza is simply one of many clinically indistinguishable influenza-like-illnesses (ILIs) from which people recover uneventfully. This season was worse than most in Australia with a record number of laboratory confirmed influenza cases (170,000), although better availability of molecular tests may account for much of this, as visits for ILI have risen only slightly above the annual average. [2] The northern hemisphere is bracing for its turn next.

Occasionally, influenza can cause severe illness or death, especially in elderly people. Sometimes different strains put unexpected population groups at risk (such as pregnant women, patients with asthma or diabetes, obese people). This begs the question of what we can do to prepare for influenza epidemics.

Three options are available: vaccination, antivirals, and hygiene interventions. Most attention is focused on vaccination, which is curious, because its effectiveness is disappointing. A recently updated Cochrane review reports that vaccination reduces laboratory-confirmed influenza only from 2% to 1%, which is imperceptible in healthy adults (including pregnant women) in normal clinical practice because of the overwhelming incidence of ILI. [3] Influenza genetic drift means revaccination is needed every year with modified antigens, introducing an element of uncertainty of each year’s effectiveness. Genetic shift (especially as new virus moves from animal reservoirs to humans, with its risk of pandemic) makes vaccination effectiveness even less certain – just when protection is most needed. Vaccination seems to have been less effective recently, especially for the predominant viruses currently in circulation (strains of influenza A H3 and B strains), with little or no protection in elderly patients against H3 last winter in the UK and elsewhere. [4,5]  Moreover, those undergoing repeat vaccinations have less protection, for unknown reasons.[6] Annual influenza vaccination (including compulsory vaccination  for health workers in residential aged care facilities [7,8]) is based on poor evidence and may be over-promoted.  

The use of the antiviral neuraminidase inhibitors is controversial. They reduce symptoms of influenza by about half a day in a 5 day illness, but any effect on secondary infections or hospital admissions, or spread of the virus in an epidemic, remains uncertain [9], and the World Health Organization has recently taken it off its Model List of Essential Medicines. [10]  

Hygiene methods include handwashing, face masks, and quarantine, and have been found to be extremely effective at protecting against acute respiratory infections in a Cochrane review – with numbers needed to treat (NNT) as low as 3.[11] Why are these methods not canvassed as heavily as vaccination or antivirals? It would be facile only to blame the industry promotion of the latter. Social norms, which are accepting of handwashing (or sterilisation in public places), mean that people baulk at wearing face masks (except in east Asian countries such Japan), nor do such norms insist that people who are infectious stay away from work or school (instead, admiring them for “soldiering on”), or cancelling mass gatherings (sports and cultural events). People (including clinicians) expect medical technology to be more effective than is realistic, [6,12,13] all the more reason for supporting sensible low technology policies, such as one Australian state’s intention to install hand hygiene dispensers on trains with a campaign that promotes “cough into your elbow.” [14]

What about the threat of influenza pandemics? In 1918/9, after the first world war, the social upheavals, such as  enormous movements of troops returning home, and a population that was exhausted from four years of war, with inadequate nutrition, as well as the lack of effective management of secondary bacterial infections, contributed to the magnitude of the disaster. Some of these contributing factors might be better in a modern recurrence, but not others, such as a vastly more mobile population, which would render quarantine isolation of an outbreak near useless. It is hard to see what could be done to mitigate a catastrophe that was not rehearsed in the avian and swine influenza epidemics.

In the meantime, it is clear we need better vaccines, which need better evaluation, and making public awareness messages that promote mask wearing and hand hygiene. [15]

Chris Del Mar is a professor of public health at Bond University, Australia.

Peter Collignon is an infectious diseases physician and clinical microbiologist at the Canberra Hospital and currently Executive Director of ACT Pathology. He is also a Professor at the Australian National University Medical School.

Competing Interests: PC: None declared.

CDM:

Consultancy, fees/honoraria:

  • National Prescribing Service Medicine Wise (NPSMedicineWise) consultations
  • RACGP’s ‘Red Book’ preventive guidelines committee
  • Therapeutic Guidelines (eTG), guidelines development
  • Remote Primary Health Care Manuals Editorial Committee
  • Royalties for 3 books (Wileys and BMJ Books) on EBM, and clinical thinking
  • Editorial work (MJA Deputy Editor; ACP Journal Club; BMJ)
  • Consultation work for BUPA (UK) on shared decision making
  • Australian Medicine Handbook, guidelines development)
  • BUPA (UK), consultation about Shared Decision Making

Grants to my institution:

  • NHMRC (Australia) two Centres for Research Excellence, one in Antimicrobial resistance
  • NIHR (UK) (Systematic review on neuraminidase inhibitors for influenza)
  • HTA (UK) (Systematic review on neuraminidase inhibitors for influenza)
  • from a private donor (for the Cochrane Collaboration ARI Group)
  • Australian Commission on Safety and Quality in Health Care (for the provision of decision aids x 3; an education module on risk communication)

Advocacy or publicly debated related matters (including the provision of expert testimony)

  • As a member of the RACGP’s Preventive Guidelines (Red Book) Committee
  • About antibiotic resistance (both for the NPS and my own research)
  • Other issues from time to time which may be relevant.

Travel subsidies

From the manufacturer of an oncology drug so I could deliver an invited conference presentation on prostate cancer screening in 2014

Prejudices

  • screening (I believe we advocate too much in Australia);
  • evidence-based medicine (not enough)
  • health literacy (insufficient focus on empirical at the expense of patho-physiological)

References:

  1. Taubenberger JK, Morens DM. Influenza: the once and future pandemic. Public Health Rep. 2010;125.
  2. Australian Government Department of Health. Australian Influenza Surveillance Report No 09 – 02 September to 15 September 2017 [http://www.health.gov.au/flureport accessed 29 Sept 2017]. 2017.
  3. Demicheli V, Jefferson T, Al‐Ansary LA, Ferroni E, Rivetti A, Di Pietrantonj C. Vaccines for preventing influenza in healthy adults (update in press 2017). The Cochrane Library. 2014.
  4. Public Health England. Influenza vaccine effectiveness in adults and children in primary care in the UK: provisional end-of-season results 2015-16 [www.gov.uk/government/publications/influenza-vaccine-effectiveness-2015-to-2016-estimates accessed 29 Sept 2017]. 2017.
  5. Kissling E, Rondy M, team IMIMs. Early 2016/17 vaccine effectiveness estimates against influenza A(H3N2): I-MOVE multicentre case control studies at primary care and hospital levels in Europe. Eurosurveillance. 2017;22(7):30464.
  6. Bodewes R, Kreijtz JH, Rimmelzwaan GF. Yearly influenza vaccinations: a double-edged sword? Lancet Infect Dis. 2009;9(12):784-788.
  7. Thomas RE, Jefferson T, Lasserson TJ. Influenza vaccination for healthcare workers who care for people aged 60 or older living in long-term care institutions. Cochrane Database Syst Rev. 2016(6):Cd005187.
  8. De Serres G, Skowronski DM, Ward BJ, et al. Influenza vaccination of healthcare workers: Critical analysis of the evidence for patient benefit underpinning policies of enforcement. PLoS ONE. 2017;12(1):e0163586.
  9. Heneghan CJ, Onakpoya I, Jones MA, et al. Neuraminidase inhibitors for influenza: a systematic review and meta-analysis of regulatory and mortality data. Health Technol Assess. 2016;20(42):1-242.
  10. Kmietowicz Z. WHO downgrades oseltamivir on drugs list after reviewing evidence. BMJ. 2017;357.
  11. Jefferson T, Del Mar CB, Dooley L, et al. Physical interventions to interrupt or reduce the spread of respiratory viruses. Cochrane Database Syst Rev. 2011(7):Cd006207.
  12. Hoffmann TC, Del Mar C. Patients’ Expectations of the Benefits and Harms of Treatments, Screening, and Tests: A Systematic Review. JAMA internal medicine. 2014;175(2):274-286.
  13. Hoffmann TC, Del Mar C. Clinicians’ expectations of the benefits and harms of treatments, screening, and tests: A systematic review. JAMA Int Med. 2017;177(3):407-419.
  14. Brennan R. Free hand sanitisers plan for public places to help stop spread of infleuenza [http://www.dailytelegraph.com.au/news/nsw/free-hand-sanitisers-plan-for-public-places-to-help-stop-spread-of-influenza/news-story/a210a19a1bcf81d7115f74e9468c8dbf] accessed 29 Sept 2017]. Daily Telegraph Sydney, 2017.
  15. Lambert LC, Fauci AS. Influenza Vaccines for the Future. N Engl J Med. 2010;363(21):2036-2044.