1. Seventh Welsh Immunisation Conference: Pandemic influenza
Professor Nick Phin University of Chester &
HPA Centre for Infections
London

2. Influenza virus
A respiratory virus with a segmented genome containing eight RNA strands
The virus is commonly categorized by two proteins on the surface
of the virus
Neuraminidase
(9 subtypes)
Haemagglutinin
(16 subtypes)

4. Role of viral neuraminidase
Neuraminidase causes the
virus to be released from
the cell wall
Stress that because the antiviral stops the release of new virus into the lungs that the sooner treatment is started the more effective and the more successful it is likely to be. This is one of the reasons that we don’t use Tamiflu after 48 hours because by then so much virus is circulating that stopping anymore is not likely to make much difference.
Antivirals like Tamiflu prevent the release of viruses from infected cells

6. Why are these two proteins important?
Haemagglutinin binds to receptors
on the cell
Virus is engulfed into cell
The virus turns the cell
into a factory producing
new viruses

7. Clinical course
Respiratory virus that attacks the lining of the respiratory system
Uncomplicated Influenza
Virus affects the upper airways
Illness lasting 5 to 7 days
Complicated Influenza
The virus affects the lower airways causing or permitting the development of a pneumonia. This is either a
Viral pneumonia (direct effect)
Bacterial pneumonia (indirect caused particularly by:
S Aureus,
S Pneumoniae,
H Influenzae

8. Viral pneumonia
The example on the left are normal lungs the example on the right are the lungs of some affected by viral pneumonia. The lungs become very stiff and lose their flexibility. There is also bleeding and fluid in the airways.

9. What makes a pandemic?
Nature June 2009

11. So what happened in 2009?
It is estimated that the first cases may have occurred as soon as September 2008 but it is probably more likely that this was in mid January 2009
Mid February - start of an outbreak of ARI in La Gloria, Veracruz. 28% of the 2,150 inhabitants affected from March 5 to April 10

13. The timeline
1 April Healthmap, a global disease alert system run by academics, flags a news story from Mexico about a strange respiratory outbreak in Veracruz State that has claimed two lives.
6 April Veratect, a US based company that scours news reports for emerging threats, reports in its subscription-only database that local Mexican health officials have declared an alert because of respiratory disease outbreak in La Gloria, Veracruz State

14. The timeline (cont)
11 April as per the International Health Regulations (IHR) PAHO, a regional office of WHO, asks the Mexican IHR “focal point” to verify the outbreak reported in the news.
12 April - Mexican PH authorities confirms to PAHO the existence of acute respiratory infections. Mexico’s focal point considers outbreak to be a “potential public health event of international importance”
Clusters of severe progressive pneumonia in young adults identified in Mexico City and San Luis Potosi

15. The timeline (cont)
15 April - boy in San Diego, California identified with a novel swine influenza from specimen taken on 30 March 2009
17 April - girl in Imperial, California identified with a novel swine influenza from early April
22 April - Mexico reports atypical influenza behaviour associated with severe pneumonia in various cities
23 April more cases identified in southern California/Texas – no connection
23 April Public Health Agency of Canada and CDC identifies novel swine flu in Mexican samples

16. The timeline
24 April the WHO issues an international disease outbreak notice
27 April the WHO raised the global pandemic alert phase to 4

17. The timeline On 30 April the pandemic alert phase was raised to 5
This is the first influenza pandemic in four decades;

18. WHO global influenza preparedness plan, 2005-2009
January 2008

19. New WHO Pandemic Phases April/May 2009

23. The timeline
On 11 June WHO raised the pandemic alert phase to 6

30. Current Global position
All countries affected – most countries have experienced some mortality
Cases now in the millions
Estimates from the US suggest 63 million (21%) US citizens infected. Studies in the UK suggest similar numbers.

31. Clinical presentation and underlying risk factors
Clinical picture consistent with seasonal influenza:
Median reported duration of illness 7 days; mean 8.5 days (range 1 to 25 days)
Generally considered a mild disease however,
Causes a small but significant number of cases of severe pneumonitis resulting in ARDS requiring ITU admission
Difficult to treat and requiring treatment modalities such as HFOV and ECMO
Significant mortality in these cases

32. Age groups – Q Surveillance ILI rate (w/e 25 October 2010)

33. Hospitalisation

37. Objectives of vaccination in a pandemic
Public health measure to prevent illness and reduce transmission in the population
Personal health measure to reduce the likelihood of illness and severe disease
Infection control measure to reduce the likelihood of infection in vulnerable people

38. Vaccine Production
Image courtesy of GlaxoSmithKline plc

39. Other issues
Vaccine safety
Guillain Barré Syndrome

40. Future Forecast
H5N1
H1N1
H3N2

41. No room for complacency – 1968/69
Use the current time to learn from the events of 2009 and refine the response
Need to maintain heightened vigilance and response
Remember the FSA!

43. Acknowledgements All my colleagues in the HPA in the:
Centre for Infections
Regional Microbiology Network
Local and Regional Services
In particular:
Richard Pebody Estelle Mclean
Laura Craig Colin Hawkins Hongxin Zhao
Barry Evans Maria Zambon John Watson