Published 15 July 2009, doi:10.1136/bmj.b2897
Cite this as: BMJ 2009;339:b2897

Editorials

How well are we managing the influenza A/H1N1 pandemic in the UK?

Pretty well, and it has served as an important rehearsal for a more lethal pandemic

News headlines this week have certainly raised anxiety over the influenza A/H1N1 (swine flu) pandemic in the United Kingdom, with reports of 17 deaths to date since the national epidemic started in late April, and one of the dead being a 6 year old girl with apparently no pre-existing medical conditions. NHS Direct telephone lines have been swamped in recent days as the epidemic continues to expand and mortality rises.

How serious is the UK epidemic, and what are the likely trends over the coming months as autumn arrives? General practice consultation rates in England for patients presenting with flu-like illness have increased and are now above the threshold for normal seasonal flu activity. The 5-14 year olds remain the age group predominantly affected, with London and the West Midlands being the worst affected regions. Mortality among clinical cases with confirmed influenza A/H1N1 infection is currently between 1 per 200 and 1 per 400. This is a higher figure than that typically seen with seasonal flu, but the true figure per case of infection will be much lower because of a high prevalence of mild symptoms not captured in the current reporting system. Many biases affect these estimates, as reported in the linked article by Garske and colleagues (doi:10.1136/bmj.b2840).¹ More detailed retrospective household studies are needed now, with serology to ascertain infection and morbidity. These are planned to take place in the coming months.

The most surprising feature of the UK epidemic is its continued growth through June and July, when seasonal flu normally drops to very low levels. This is apparent not only in the UK, but also in the United States and Canada. The high numbers of cases in these countries, relative to other regions (except South America—the epidemic is believed to have originated in Mexico²), probably says more about the efficiency of public health reporting systems and diagnostic capabilities than regional differences in transmission. At present, 135 countries have reported confirmed cases of swine flu; many more probably have epidemic spread but lack reporting systems to capture incidence, morbidity, and mortality.

The reasons for epidemic expansion in the summer months in northern hemisphere countries are not well understood. The observed trends may change views about the relative importance of herd immunity and seasonal factors such as humidity, temperature, and human behaviour as determinants of the incidence of flu. The high susceptibility of human communities to the new virus may imply that seasonal fluctuations in transmission are insufficient, in a fully naive population, to drive the reproductive number (average number of secondary cases generated by one primary case³) below unity in value, as normally happens in a partially susceptible population exposed to a virus closely related to that circulating in the previous year. The onset of school holidays in the northern hemisphere should decrease transmission markedly, but the epidemic is likely to be sustained over August before it starts to expand vigorously again in the autumn, as children reassemble for school. Health services may well be stretched in the UK, as will the economy, owing to high rates of absenteeism from work.

How well prepared was the UK for this current outbreak, given the intense planning that previously took place for the management of a pandemic of the much more lethal, but much less transmissible, H5N1 bird flu virus? Government machinery swept into action quickly in late April, and the assembly of advisory groups for COBR (Cabinet Office Briefing Room) meetings with ministers and civil servants worked well. The UK was well placed in terms of stocks of antiviral drugs and with respect to pre-orders of a vaccine specific to an emergent pandemic flu strain. Supplies of the vaccine will be available in early autumn, and the government aims to vaccinate most of the population. Plans are currently being drawn up to determine the priorities for immunisation as stocks build up in the autumn months.

Antiviral drugs were used to good effect in the early phase of the UK epidemic as prophylaxis, in a containment strategy targeted at contacts within households, schools, and work settings. Retrospective analyses tentatively suggest that this strategy slowed transmission, but as suggested by previous mathematical analyses of flu spread, this delayed epidemic growth only by a few weeks.⁴ Now the strategy has shifted to the treatment of cases and those most at risk of serious morbidity from infection after contact with a case. This change in treatment strategy is sensible and conserves the supply of antiviral drugs for those most in need as the epidemic expands in the coming months.

What could be improved? In common with other countries’ pandemic plans, those in the UK lacked detail in many areas. These included the logistics of drug delivery, how to ensure and monitor good compliance to the prescribed antiviral treatment course, the provision of sufficient diagnostic services, data capture and reporting in primary and secondary care settings and on a national scale, monitoring viral evolution, clinical case definition, and the setting of priorities for treatment plus vaccination. Technologies to help in protection and containment such as face masks and rapid diagnostic tools did not receive high priority in planning, but these tools would be of great value within healthcare settings in rapidly expanding flu epidemics.⁵

In the early stages, some media websites provided much more useful information to the public in tracking the unfolding epidemic than official government sites. This has now been rectified. The UK performed much better than most, particularly the US, where in the early stages of epidemic growth, case information on attack rates and morbidity was released slowly, despite high case numbers. UK scientists, in collaboration with Mexican colleagues, were the first to publish epidemiological analyses of the emerging epidemic.²

The UK’s plan to capture details of the first 100 cases to inform policy formulation worked in part. Guidelines for use in clinical settings on the information that needs to be gathered and on the procedures needed to follow up cases and contacts, to obtain viral isolates and serum or saliva, and to track the course of viraemia in treated and untreated patients all need to be improved. The Health Protection Agency has performed sterling work under a rapidly expanding case load. However, improvements could be made to ensure better communication between groups within the agency; better and more rapid access to data; and better use and integration of resources from universities, which have much scientific, epidemiological, and clinical expertise, plus access to facilities. Use of such academic resources could greatly facilitate rapid epidemiological analyses, through developing clear criteria for clinical case definition, defining guidelines for when to use antiviral drugs, and monitoring viral evolution—especially in the context of drug resistance and varied compliance to prescribed drug regimens.

Overall, much has been learnt in the past few months from what, thankfully, still seems to be mild flu in most of those infected. In many ways, the emergence of influenza A/H1N1 has served as an important rehearsal worldwide for a future and perhaps much more lethal pandemic. A thorough and frank "lessons learnt" exercise must be performed once the epidemic wanes.

Cite this as: BMJ 2009;339:b2897

¹ Faculty Building, South Kensington Campus, Imperial College London, London SW7 2AZ

Research methods and reporting, doi:10.1136/bmj.b2840

---

Competing interests: RMA is a non-executive director of GlaxoSmithKline and non-executive director of Imperial College NHS Trust.

Provenance and peer review: Commissioned; not externally peer reviewed.

References

1. Garske T, Legrand J, Donnelly CA, Ward H, Cauchemez S, Fraser C, et al. Assessing the severity of the novel influenza A/H1N1 pandemic. BMJ 2009;339:b2840.[Free Full Text]
2. Fraser C, Donnelly CA, Cauchemez S, Hanage WP, Van Kerkhove MD, Hollingsworth TD, et al. Pandemic potential of a novel strain of influenza A (H1N1): early findings. Science 2009 [Online 11 May 2009]; doi:10.1126/science.1176062.
3. Anderson RM, May RM. Infectious disease of humans: dynamics and control. Oxford: Oxford University Press, 1991.
4. Ferguson NM, Cummings DAT, Cauchemez S, Fraser C, Riley S, Meeyai A, et al. Strategies for containing an emerging influenza pandemic in Southeast Asia. Nature 2005;437:209-14.[CrossRef][Medline]
5. Jefferson T, Foxlee R, Del Mar C, Dooley L, Ferroni E, Hewak B, et al. Physical interventions to interrupt or reduce the spread of respiratory viruses: systematic review. BMJ 2008;336:77-80.[Abstract/Free Full Text]

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    StumbleUpon    Technorati    What's this?

Relevant Articles

Case definition is too loose

Emma J Wilson, John Williams, and Brendan McCarron
BMJ 2009 339: b3365. [Extract] [Full Text]

Inaccurate estimation of cases?

Patrick Lush
BMJ 2009 339: b3246. [Extract] [Full Text]

Data, please

Wilfrid Treasure
BMJ 2009 339: b3247. [Extract] [Full Text]

Too soon for congratulations

Tony M Hirst
BMJ 2009 339: b3248. [Extract] [Full Text]

Respirator fit testing, anyone?

Abhijoy Chakladar, Peter O Beaumont, and David R Uncles
BMJ 2009 339: b3254. [Extract] [Full Text]

Predicting and preparing for pandemic flu

Fiona Godlee
BMJ 2009 339: b2988. [Extract] [Full Text]

Assessing the severity of the novel influenza A/H1N1 pandemic

Tini Garske, Judith Legrand, Christl A Donnelly, Helen Ward, Simon Cauchemez, Christophe Fraser, Neil M Ferguson, and Azra C Ghani
BMJ 2009 339: b2840. [Full Text]

Physical interventions to interrupt or reduce the spread of respiratory viruses: systematic review

Tom Jefferson, Ruth Foxlee, Chris Del Mar, Liz Dooley, Eliana Ferroni, Bill Hewak, Adi Prabhala, Sree Nair, and Alex Rivetti
BMJ 2008 336: 77-80. [Abstract] [Full Text] [PDF]

This article has been cited by other articles:

• Wilson, E. J, Williams, J., McCarron, B. (2009). Case definition is too loose. BMJ 339: b3365-b3365 [Full text]  
• Lush, P. (2009). Inaccurate estimation of cases?. BMJ 339: b3246-b3246 [Full text]  
• Treasure, W. (2009). Data, please. BMJ 339: b3247-b3247 [Full text]  
• Hirst, T. M (2009). Too soon for congratulations. BMJ 339: b3248-b3248 [Full text]  
• Baker, M., Marshall, M. (2009). What is and is not a "flu lead". BMJ 339: b3250-b3250 [Full text]  
• Chakladar, A., Beaumont, P. O, Uncles, D. R (2009). Respirator fit testing, anyone?. BMJ 339: b3254-b3254 [Full text]  

Rapid Responses:

Read all Rapid Responses

Meanwhile, back on planet Earth

Douglas Salmon
bmj.com, 16 Jul 2009 [Full text]

How well are we actually managing the influenza pandemic? Perhaps not so well

Abhijoy Chakladar, et al.
bmj.com, 19 Jul 2009 [Full text]

Is the initial management of influenza A/H1N1 pandemic in the UK a good or a bad example?

Antoni Trilla, et al.
bmj.com, 20 Jul 2009 [Full text]

diagnosis of swine flu A/H1N1

patrick lush
bmj.com, 21 Jul 2009 [Full text]

Re: diagnosis of swine flu A/H1N1

Anne Savage
bmj.com, 24 Jul 2009 [Full text]

Heightening anxiety

Richard J Thorne
bmj.com, 28 Jul 2009 [Full text]

Tamiflu

I M Peek
bmj.com, 29 Jul 2009 [Full text]

Cum scientia ...

Wilfrid Treasure
bmj.com, 30 Jul 2009 [Full text]

Appendicitis mortality higher than swine flu

Guy F Nash, et al.
bmj.com, 30 Jul 2009 [Full text]

Too soon to congratulate ourselves

Tony M Hirst
bmj.com, 31 Jul 2009 [Full text]

The State of Swine Flu Pandemic in developing countries

Aamir Shahzad, et al.
bmj.com, 31 Jul 2009 [Full text]

Re: The State of Swine Flu Pandemic in developing countries

Sujaa Mary Rajagopal Arokiadass, et al.
bmj.com, 1 Aug 2009 [Full text]

Three management plans

Andrew Green
bmj.com, 3 Aug 2009 [Full text]

Empirical prescription of Oseltamivir can delay diagnosis of potentially serious problems in children

Peter A de Halpert
bmj.com, 6 Aug 2009 [Full text]

Re: Empirical prescription of Oseltamivir can delay diagnosis of potentially serious problems in children

Trefor J Roscoe
bmj.com, 13 Aug 2009 [Full text]

Pandemic Flu is delaying the diagnosis of common childhood disease - Impact on Children's Intensive Care

Richard A Neal, et al.
bmj.com, 13 Aug 2009 [Full text]

The Perils of Swine Flu

Emma J Wilson, et al.
bmj.com, 14 Aug 2009 [Full text]

Organizative proposals in Spain for influenza crisis

Miguel A. Maņez
bmj.com, 8 Sep 2009 [Full text]

Online poll

Find out more here>> and here>>