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13 November 2013

Travel Health: Summary of yellow fever vaccinations given in Scotland: 2012

Introduction

Yellow fever is currently the only disease for which an International Certificate of Vaccination or Prophylaxis (ICVP) may be required for entry into a defined list of countries under the International Health Regulations.1 The ICVP must be signed and stamped by an appropriate person and is valid only when a WHO-approved vaccine has been administered. The United Kingdom (UK) as a signatory to the IHR is required to designate specific yellow fever vaccination centres (YFVCs) 'in order to ensure the quality and safety of the procedures and materials employed'.2

The statutory responsibility for designating YFVCs in Scotland belongs to Health Protection Scotland (HPS), having been passed from the Scottish Government in December 2006. Through a programme of registration, training, and audit, HPS maintains and improves overall standards and consistency of practice within YFVCs in Scotland. This ensures that the UK meets its obligations under the IHR as well as contributing to protecting the health of travellers from Scotland.

One of the duties of any designated YFVC in Scotland is to keep appropriate records of all yellow fever vaccine they administer for a period of 10 years, submitting both annual returns of vaccine utilisation and any adverse event reports to HPS on an annual basis. Here we report on the sixth year of returns for the period 1 January to 31 December 2012.

Methods and analysis

In 2012, 234 YFVCs were registered with HPS, compared with 222 in 2011. All 234 YFVCs submitted a return on the number of doses of vaccine administered in that centre for the calendar year 2012 (RR 100%). The data was collated onto a web-based database. For the purpose of this analysis, data was extracted and analysed using Microsoft Excel. Population data for 2012 was obtained from the General Register Office for Scotland.3

Yellow fever vaccination centres in Scotland in 2012

Of the 234 vaccination centres the majority were in Greater Glasgow & Clyde, Lothian and Grampian NHS Boards; 55(24%), 44(19%), and 36(15%), respectively (Figure 1). Shetland, Orkney, and Western Isles NHS Boards contributed the smallest number of centres, at 1 (<1%), 2 (1%), and 2 (1%).

In terms of YFVCs per head of population, there were 4/100000 for the whole of Scotland in 2012. By NHS board (Figure 2), Orkney, Western Isles, Grampian and Highland had the highest numbers per head of population at 9/100000, 7/100000, 6/100000 and 6/100000, respectively. Lanarkshire (1/100000) Ayrshire & Arran (2/100000), and Borders (3/100000) had the lowest numbers of centres per head of population.

Doses of YFV administered in YFVCs in Scotland in 2012

In 2012, the 234 YFVCs administered 11193 doses of yellow fever vaccine to travellers, down 1% from 2011 (N=12253) and down 14% from 2008 (13084) when returns first began being collated. The number of doses administered per centre across Scotland ranged from 0 to 976 (Mean + standard error =48+6). The majority (71%: 167/234) of the centres administered between 1 and 50 doses (Figure 3), with 6% (14/234) administering no doses, and 3% (7/222) administering over 300 doses in the calendar year 2012.

With respect to distribution of doses by NHS board area (Figure 4), the majority of doses were administered in Grampian (3368 doses, 30% of total), Lothian (2378, 21%) and Greater Glasgow & Clyde (2525, 23%). Shetland (38, <1%) Orkney (53, <1 %) and Western Isles (61, %) NHS Boards had the lowest number of doses administered.

No serious adverse events were reported among the 234 YFVCs delivering the 11193 doses, the cumulative total of adverse events since 2008 being 1 in 61716 doses.

Discussion

The current yellow fever vaccine has been available for 70 years,4, 5 being derived from seed lots in turn derived from a 17D strain developed in 1940s.6 Mandatory vaccination in the case of yellow fever is aimed at preventing country-to-country spread of disease, and is often applied to vulnerable countries: i.e. countries without yellow fever disease but where the mosquito vector and monkey host are present.

The yellow fever vaccine recommended by WHO is both safe and effective.5, 6 The WHO Strategic Advisory Group of Experts on Immunization recently concluded that a single dose of vaccine is likely sufficient to confer life-long immunity against yellow fever virus infection.7 Risk assessment, however must be carried out for each traveller as there may be circumstances where revaccination may be indicated. Boosters are required every 10 years if there is a certificate requirement. Serious adverse events occur at very low rates8 being mostly allergic complications and yellow fever virus-associated neurotropic disease (YEL-AND). YEL-AND was estimated to occur at a rate of 0.4-0.8 cases/100000 doses, although that rate was higher in those aged over 60 years.5 Another low incidence but serious adverse event observed in recent years is yellow fever virus-associated viscerotropic disease (YEL-AVD). This has an estimated incidence of 0.3-0.4 cases/100000 doses being higher in those with a history of thymus disease and, like YEL-AND, higher in older aged people. The low incidence of adverse events observed to date in Scottish YFVCs is in keeping with those estimates.

As in any specialty, in travel medicine before giving a vaccine a health professional should carry out a risk assessment considering not only the risk of the vaccine preventable disease, but also the risk of the intervention. In the case of yellow fever the chance of the traveller being infected with yellow fever virus via the bite of an infected mosquito must be weighed against the chance of yellow fever vaccination resulting in an adverse event. In Scotland biennial on-line training as well as face-to-face training and email correspondence ensure that YFVCs are kept up-to-date with developing trends and any pertinent WHO recommendations.

The registered medical practitioner responsible for the YFVC must agree to comply with the following Conditions of Registration and sign to this effect below:
1. The centre will administer only yellow fever vaccines approved by the World Health Organization (WHO).
2. All yellow fever vaccinations carried out at the centre will be performed by the responsible medical practitioner, or by a suitably qualified person (nurse or doctor) acting under his/her direction and control.
3. Facilities for administering and storing vaccines will be of an acceptable standard. 
4. Appropriate policies for safe administration of yellow fever vaccine will be in place, and all staff involved in administration of vaccine will be appropriately trained.
5. The centre will comply with staff training as required by Health Protection Scotland (HPS).
6. The centre will keep appropriate records of all vaccinations administered.
7. The International Certificate of Vaccination or Prophylaxis will be completed in accordance with WHO International Health Regulations (IHR), bearing a specified YFVC registered stamp and signed by an authorised vaccinator.
8. All vaccine associated adverse events will be reported to the Medicines and Healthcare Products Regulatory Agency (MHRA).
9. All vaccine associated adverse events will be reported to the Medicines and Healthcare Products Regulatory Agency (MHRA).
10. HPS will be notified immediately of any changes, which may affect the centre’s registration status.
11. If requested, HPS will be given access to the centre or receive copies of YFVC records to ensure that the centre is complying with the conditions of registration.
12. The centre’s status as a designated YFVC will be reviewed biennially.

 

Where YFV is contraindicated or where the risk of adverse reaction is considered greater than that for yellow fever disease but there is a certificate requirement, then an exemption certificate may be considered, although the risk remains that the destination country they are travelling to may not recognise such a certificate.8

All designated centres sign up to a 'Code of Practice' which stipulates standards which have to be met in relation to safety, training, record keeping and reporting, particularly of adverse events.

Since being tasked with overseeing the designation of YFVCs, HPS has established a Yellow Fever Programme, to facilitate registration, training, monitoring and audit of centres in Scotland, consistent with that for England, Wales and Northern Ireland.

In conclusion, designated YFVCs in Scotland continue to comply with conditions of registration. It is hoped through the audit process that improvements may be made both in practice and in knowledge so that services can be further improved.

Further detail on the Scottish Yellow Fever Programme can be found on the HPS website (http://www.hps.scot.nhs.uk/yellowfever/index.aspx). This includes how to apply for designation as a YFVC in Scotland; downloadable application and information pack; and a list of resources for centres. There is also a YFVC locator function which allows individuals, including members of the public, to search for their nearest YFVCs across Scotland, and view the services on offer.

Acknowledgements

HPS would like to thank the yellow fever vaccination centres (YFVCs) throughout Scotland who have co-operated with and supported the implementation of the Yellow Fever Programme (YFP).

References

  1. WHO. International Health and Travel. Geneva: World Health Organization, 2011.
  2. WHO. International Health Regulations 2005. Second ed. Geneva: World Health Organization, 2005.
  3. General Register Office for Scotland. Mid-2012 Population estimates. http://www.gro-scotland.gov.uk/statistics/theme/population/estimates/mid-year/2012/index.html: Accessed November 2013.
  4. Barnett E. Yellow fever: epidemiology and prevention. Clin Infect Dis. 2007 44(6):850-6.
  5. Staples JE, Gersham M, Fischer M. Yellow fever vaccine: Recommendations of the Advisory Committee on Immunizations Practices (ACIP). MMWR 2010;59(RR07):1-27.
  6. PAHO. Control of yellow fever: field guide. Scientific and Technical Publications No 603. Washington DC: PAHO, 2005.
  7. WHO. Meeting of the Strategic Advisory Group of Experts on Immunization, April 2013. WER; 88, 201-216.
  8. Hardiman M, Wilder-Smith A. The Revised International Health Regulations and their relevance to travel medicine. Journal of Travel Medicine 2007;14:141-144.

Note: the last report on YFVC performance appeared in HPS Weekly Report 46/46 (at http://www.hps.scot.nhs.uk/ewr/redirect.aspx?id=53243).

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Vol: 47 No: 46 Year: 2013 Page:

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