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Volume 3 No 21; 29 May 2009

NIBSC produces swine flu vaccine candidate

A crucial step towards large-scale production of a vaccine against swine flu has been completed in the UK by the National Institute for Biological Standards and Control (NIBSC), part of the Health Protection Agency.

A strain of virus suitable for vaccine manufacture has been produced and is being made available to the pharmaceutical industry and other flu laboratories.

NIBSC is one of a handful of laboratories around the world, belonging to a WHO collaborative network, that have been racing to produce a strain of virus suitable for manufacturing vaccine in eggs, the mainstay of influenza vaccine production. Without suitable starting strains vaccine production on a global scale cannot begin.

The process of developing a vaccine candidate involves creating a hybrid between the strain of virus that is causing disease and a tried and tested laboratory strain. This process has been used successfully over many years both in the development of seasonal vaccine candidates and for an H5N1 bird flu vaccine strain. The idea is to make a virus that is recognised by the human body as the 'real swine H1N1 virus' but that is safe and easy to grow up in large quantities in vaccine manufacturing facilities.

The NIBSC team used a technique known as reverse genetics to build the new virus. This involved taking the crucial gene sequences (encoding the viral proteins recognised by the body's immune system) from the new swine flu virus and combining them with a complementary set of gene sequences from the laboratory strain using recombinant gene technology. The resulting virus was then 'rescued' and tested to ensure it had the right characteristics for a swine flu vaccine.

Further information

1.'Health Protection Agency produces swine flu vaccine candidate', (HPA press release, 28 May 2009). HPA website: National Press Releases.

2. 'Health Protection Agency leads work on gaining greater understanding of swine flu virus', (HPA press release, 8 May 2009). HPA website: National Press Releases.

Influenza A/H1N1 (‘swine-lineage’): UK situation at 29 May 2009

On Friday 29 May, the number of confirmed and possible cases of swine-lineage influenza A/H1N1 in the United Kingdom was 215: 200 in England, one in Northern Ireland, 14 in Scotland and none in Wales (table 1) [1].

Table 1: Confirmed cases by Region and Devolved Administration, United Kingdom as reported by 29 May 2009


Confirmed cases

East of England


East Midlands




North East


North West


South East


South West


West Midlands


Yorkshire & Humberside


Total England


Northern Ireland








One hundred and thirty seven cases were under laboratory investigation in the UK.

Assumed mode of transmission, age breakdown

In the light of the swine-lineage influenza outbreak, the Agency has recommenced publication of its Weekly National Influenza Report [2], normally published only during the seasonal winter flu period.

The first report, published on 28 May 2009 (week 22), indicated that, of the 185 cases confirmed at 26 May (figure 1):

  • fifty-one are assumed to have acquired the virus abroad,
  • thirty-seven were assumed to be secondary cases (following contact with a case who acquired it abroad),
  • eighty-three were assumed to be tertiary cases (acquired through contact with a secondary or sporadic case),
  • eight were sporadic cases (no known travel history or contact with a known case), and
  • the determination of the route of transmission was pending in six cases.

Figure 1. Confirmed UK cases of influenza A (H1N1swi) by date of onset and assumed mode of transmission, 26 May 2009 (n=157*)

Of all outbreak cases, the highest number of cases have been seen in children and young adults (figure 2).

High numbers of cases were seen in London and the West Midlands, explained by two large school outbreaks reported in South East London and Birmingham.

Figure 2. Cases of laboratory confirmed influenza A (H1N1swi) by age-group and gender, 26 May 2009 (n=184*), United Kingdom

* One female case does not have the age recorded.

Clinical indicators and syndromic and other surveillance

The rate of clinically reported influenza-like symptoms increased across the UK when the outbreak was declared (in week 18) but most indicators have subsequently declined and remain at low levels, only slightly higher than might be expected for the time of year [2].

NHS Direct has an existing algorithm for 'cold/flu' calls. In response to the current situation, a new algorithm was introduced to handle 'swine flu' calls. When both indices are added together, they show that the 'estimated total' proportion of cold/flu calls to NHS Direct has continued to decline since the initial peak [2].

The percentage of cold/flu calls received by NHS Direct also peaked and decreased very quickly, a peak that was not reflected in other indicators, eg fever or cough, suggesting that this could have been due to public concern about 'swine flu' rather than an increase in illness in the community.

To help identify cases of swine flu in the community, surveillance will continue throughout the summer. Besides making use of NHS Direct data, in England this will include the collection of data from 3,300 GP surgeries across the country and the testing of patient samples from over 100 surgeries. Information on flu activity will also be provided via a network of boarding schools.

HPA is issuing regular guidance to GPs on the testing of possible cases and plans to increase the number of surgeries participating in surveillance schemes, and to facilitate more widespread testing in communities where cases of swine flu have been identified, are currently being implemented.

HPA guidance

An Epidemiological Data section (currently updated daily) was added to Swine Influenza pages on the Agency website, which now include sections on:

The Information for Health Professionals section has been subdivided into subsections on:

Key guidance documents, in their most recently-updated version, remain available from the same pages, for example:

  • the swine flu case definition [3],
  • proposals for a Classification of Swine Flu Cases [4];
  • "Algorithm S5" for health professionals on the management of returning travellers [5];
  • practical advice for health professionals investigating possible cases [6];
  • "Algorithm P5" for health professionals on the management of suspected cases [7];
  • advice on exclusion from schools and workplaces [8] and for boarding schools [9]; and
  • information on face masks and related information covering healthcare environments [10].


References and links

1. 'Update on confirmed swine flu cases', (HPA press release, 29 May 2009). HPA website: National Press Releases.

2. 'HPA Weekly National Influenza Report', 28 May 2009 (week 22). HPA website: Swine Influenza Epidemiological Data.

3. Swine flu case definition (version 2.0, updated 9 May), available from the Swine Influenza Information for Health Professionals pages on the Agency website.

4. Classification of Swine Influenza Cases (19 May), available from the Swine Influenza Information for Health Professionals pages on the Agency website.

5.Algorithm for the management of suspected cases of swine influenza (returning travellers and visitors from countries affected by swine influenza A/H1N1 or contacts) (version S5, updated 22 May), available from the Swine Influenza Information for Health Professionals pages on the Agency website.

6.Standard practical advice for investigating individuals with possible swine influenza infection  (version 4, updated 22 May), available from the Swine Influenza Information for Health Professionals pages on the Agency website.

7. Actions and post exposure prophylaxis for close contacts of probable or confirmed human case(s) of swine influenza A/H1N1 (version P5, updated 16 May 2009), available from the Swine Influenza Information for Health Professionals pages on the Agency website.

8. Advice on exclusion from schools and workplaces (updated 7 May 2009), available via the Swine Influenza public advice pages.

9. Managing a flu-like illness in a boarding school during the current swine flu outbreak (version 2, 17 May 2009), available from the Swine Influenza Information for Health Professionals pages on the Agency website.

10. The use of personal protective equipments (PPE) by healthcare workers in close contact with possible, probable and confirmed cases of swine flu during the pre and pandemic phases (15 May 2009), available via the Swine Influenza Information for Health Professionals pages.

Regulatory guidance and best practice advice on food handlers' fitness to work

The Food Standards Agency has published revised guidance on food handlers' fitness for work, intended to help managers and staff in food businesses prevent the spread of infection. The illnesses and symptoms which staff should report, and the steps managers should take in response, are reviewed in the context of both relevant legal provisions and best practice.

The publication updates and replaces guidance issued by the Department of Health in 1995. For the first time, the guidance applies to all UK food business operators except primary producers (eg farmers and growers).

The guidance is non-binding, providing informal advice that individual businesses may choose whether or not to follow. It is hoped, however, that it will prove useful in meeting legal food hygiene obligations and maintaining high standards of food safety.


1. FSA. Food handlers: fitness to work - a practical guide for food business operators, May 2009. Downloadable at: