16 September 2004 : Additional caution for the use of yellow fever vaccine

A letter to the Lancet ( 11 th September 2004 ) from the Yellow Fever Vaccine Safety Working Group in the US has suggested an additional caution for the use of yellow fever vaccine.

Their work found that thymus disease and thymectomy appear to be over represented among cases of yellow fever vaccine associated viscerotropic disease. They suggest that patients with a history of thymus disorders should not be vaccinated with yellow fever vaccine.

In view of these findings, it would appear prudent for all health professionals to follow these recommendations at present.

The conclusion of the Working Group was as follows:

'Yellow fever vaccine provides essential protection to people travelling to or living in areas where yellow fever is endemic or epidemic. However, health-care providers should carefully consider the benefits and risks of vaccination for elderly travellers, and should ask about a history of thymus disorder or dysfunction, irrespective of age, including myasthenia gravis, thymoma , thymectomy , or DiGeorge syndrome, before administering yellow fever vaccine. If travel plans cannot be altered to avoid yellow fever-endemic areas, people with a history of thymus disease should consider alternative means of yellow fever prevention, including use of insect repellents, containing N, N- diehtyl-metatoluamide (DEET) and permethrin, and other behaviours to reduce mosquito bites. We encourage health-care providers to report all cases of yellow fever vaccine-associated adverse events so more information can be gathered about risk factors for yellow fever vaccine-associated viscerotropic disease.'

Barwick R. History of thymoma and yellow fever vaccination . Lancet 2004; 264: 936

In the UK reports of adverse events should be made through the yellow card system. In addition, NaTHNaC would appreciate being informed of any such events after the yellow card has been completed (Please inform us by email at yellowfever@uclh.org, or by phone on 0845 155 5000 ex 5943).

The advice of the US Working Group has also been disseminated internationally via Geosentinal , a global surveillance network of the International Society of Travel Medicine and CDC, Atlanta .