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Introduction

At the end of 2008, issues that dominated the news were terrorism, climate change and the biggest global recession since the 1920s. No mention of influenza. In the background however, scientists and public health professionals had been planning for the possibility of an influenza pandemic for several years. Pandemics occur when a completely new strain of influenza develops and the whole population are susceptible to it. In recent years most experts have been concerned about Avian (bird) flu which caused large numbers of bird deaths and also caused illness among people1. For this reason we were at World Health Organisation (WHO) alert level 'phase 3' at the start of 2009 (see Table 1). However, unknown to us all, a flu pandemic was beginning to make its presence felt in Mexico - Influenza A (H1N1).

The start of Swine Flu (H1N1)

In early 2009, Mexican virologists initially believed that they were dealing with a continuation of their seasonal flu when reports of flu-like illnesses first emerged. This led to delays in realising and confirming that this was in fact a new influenza sub-type. The first official reports of a swine flu outbreak in Mexico were made on 24th April 20092.

On the same day, WHO issued a Global Alert and on Sunday 26 April 2009, WHO declared the situation a public health emergency of international concern3. The following day they raised the alert level for Swine Influenza to 'phase 4' across the world because there was evidence of human-to-human transmission and confirmed cases were appearing in other countries4.

Twenty people in the USA were confirmed, six in Canada and one in Spain5. Television pictures were beamed around the world showing empty streets in Mexico City and public sector workers in 32 Mexican States wearing SARS masks.

Governments around the world were encouraged by WHO's assistant Director General in charge of health security (Dr Keiji Fukuda) to 'look at the situation very seriously'5.

On the same day that the WHO raised its flu alert level to 'phase 4', its presence was confirmed in Scotland. On Monday 27 April 2009, it was confirmed that a couple who had just returned from Mexico had been admitted to Monklands Hospital in Lanarkshire the previous weekend and were the first Scots to have been infected with Influenza A (H1N1)2. Scotland went into 'containment' mode6.

WHO raised its flu alert level to 'phase 5' on 29th April 2009, following confirmation of person-to-person transmission in the USA in addition to Mexico7. 'Phase 5' means there are large clusters of people with flu but person-to-person spread is localised. It also means that for the authorities, response plans must be ready for instant implementation/activation when required.

The speed at which this strain of flu went round the world took many by surprise and put an almost unbearable strain on the health professionals trying to maintain a 'containment' strategy. By 8th May 2009, there were 39 confirmed cases in the UK8. The Foreign Office advised against all but essential travel to Mexico and 24 countries had confirmed cases8.

WHO alert level moved to 'phase 6' on 11th June 20099 and the 'containment' strategy was relaxed shortly thereafter. This relieved some of the pressure on health professionals as it was clear that the virus was spreading in the community and could no longer be contained. Containment contributed greatly to slowing the rise in numbers of infections in Scotland. This gave the whole country time to prepare and gave pharmaceutical companies time to develop an effective vaccine.

[ Table 1 ] Phases in emergence of influenza pandemic (WHO 2005)
Inter pandemic period
Phase 1 No new influenza sub-types detected in humans.
Phase 2 No new influenza sub-types detected in humans but circulating animal influenza virus sub-type poses a substantial risk of human disease.
Pandemic alert period
Phase 3 Human infection(s) with a new sub-type but no human to human spread.
Phase 4 Small clusters with limited human to human transmission.
Phase 5 Large clusters but human to human spread remains localised.
Pandemic period
Phase 6 Pandemic with increased and sustained transmission in general population.

Source: WHO (2005) 17

Public Health Response

As the global public health community was alerted about potentially linked cases of H1N1 during week beginning April 20, 2009, it swung into action. By April 26, the first global lecture on H1N1 was posted on the internet as part of the International Supercourse, a tool for sharing public health knowledge and expertise rapidly and freely. At the same time laboratory scientists associated with the Universities in Edinburgh were working with international colleagues to improve identification and tracking of the virus and undertake the preparatory work necessary before vaccine development could begin.

A similar process had been undertaken for SARS, with public health staff collaborating on the surveillance and spread of information.

The decision to try to slow down spread of the virus by containing it as much as possible resulted in a huge amount of public health activity. Health Protection Teams were stretched to capacity in all Health Board areas across Scotland. The whole department in NHS Lothian was involved in supporting the H1N1 response.

In the first few weeks, no-one knew just how serious an infection H1N1 would be. Individuals with any flu-like illnesses returning from parts of the world where flu was spreading had to be screened and treated6. People with infection were kept at home and they were given antiviral medication along with any contacts who could have been exposed. The Health Protection Team and public health staff on call were responsible for contact tracing anyone who might have been exposed, collecting detailed clinical information on those with confirmed illness and by working with other departments in NHS Lothian, arranging for treatment to reach people as quickly as possible. Containment also meant infection control teams had to provide support to hospital staff to ensure staff and patients were protected from the virus. Anti-viral drugs such as Oseltamivir (Tamiflu) and Zanamivir (Relenza) were prescribed for those who had had close contact with confirmed cases.

At an organisational level, health service providers across Scotland were urged to review their business/service continuity arrangements; look at ways of enhancing and preserving essential supplies; and finalise plans for predistribution of any stockpiled items such as personal protective equipment (face masks, gowns and gloves), anti-viral drugs, vaccines and antibiotics2. The Government also considered cancelling pop concerts and sports events.

Diagnosis and prognosis

A clear priority right from the start of this pandemic was to find out as much as possible about this novel illness. Information was gathered from across the world which showed that most people infected recovered fully within a week, even without medical treatment. As expected, there are differences between seasonal flu epidemics and this flu pandemic. Many severe cases occurred in previously healthy young people who had no obvious predisposing factors that increase the risk of severe illness10. However, people with certain underlying medical conditions, including pregnancy, were found to be at increased risk and concern focused on the clinical course and management of the small number of patients who rapidly developed very severe progressive pneumonia10. Research on this will continue to ensure that treatment is as effective as possible.

Vaccination

People can protect themselves against influenza, particularly by taking care over hand hygiene so that the virus doesn't spread so easily. As well as this simple rule the best way to protect against influenza is through vaccination.

Vaccination prevents individuals becoming infected and prevents transmission of the disease. It was very important that a vaccine for this new strain of flu was developed and safety tested quickly. The first vaccine was produced in Australia in August 2009 and was approved for use in Australia, US and China by mid September11. This meant that vaccines safe for human use could be produced in significant quantities. Further tests in Europe led to licenses for use in Europe being granted for two vaccines on 7th October 200912, 13.

A vaccination programme for Lothian was developed, and put in place by public health and other experts over several months preceding the arrival of the vaccine. Priority groups were identified at a Scotland wide level, informed by information collected from around the world about which people were most likely to become very ill or die because of the virus. Most people only required one dose of the vaccine but some children under ten with underlying illnesses and people with a poor immune response need two doses.

The priority groups are14:

  • individuals aged 6 months and up to 65 years in the current seasonal flu vaccine clinical at-risk groups;
  • pregnant women, subject to licensing considerations;
  • household contacts of immunocompromised individuals;
  • people aged 65 and over in the current seasonal flu vaccine clinical at-risk groups ; and
  • frontline health and social care staff (defined as for seasonal flu).

The vaccination programme started in Lothian on Wednesday 21st October 2009 and over the first two days of the programme 2229 H1N1 vaccinations were given to frontline healthcare staff15. Patients were also among the first to be immunised. Immunisation of healthy children is the next priority.

Final thoughts

The story of H1N1 influenza is not over yet. It is likely that the virus will continue to circulate for some time. People have worked extremely hard to protect the health of the population, learning from earlier pandemics. There is a lot to learn from our experiences so far. Managing H1N1 has tested emergency planning, health protection teams, infection control teams, local authority colleagues, and of course all primary care and secondary care services. No one agency could have adequately protected public health, the only way this has been achieved has been through working flexibly together. We would like to take this opportunity to thank everyone who has contributed.

Key Messages:

  • The best thing you can do to protect yourself and others is to follow good hygiene practices to prevent the spread of germs. Always carry tissues; use clean tissues to cover your mouth and nose when you cough and sneeze; bin the tissues after one use - 'Catch it, bin it, kill it'16.
  • Hand hygiene: Wash your hands with soap and hot water, supplemented by a sanitiser gel where soap and water are not available.
  • Vaccine: we strongly encourage everyone who is offered the vaccine to take it.
  • Keep yourself up to date with developments by going to the Scottish Government's swine flu web pages: http://www.scotland.gov.uk/Topics/Health/health/AvianInfluenza/mexicanswiuneflu
  • If you think you need help call NHS 24 on 08454 24 24 24.