Evidence-based prescribing commentary

Evidence-Based Prescribing Commentary

Yellow febrility inoculation in travelers of advanced age

Grant Dex MB ChB DRCOG MRCGP PG Cert Health Services Research

Question: Professor Tony Avery

“I was recentlyfaced with the quandary of whether or non to give a xanthous febrility vaccinum to an older patient ( an 83 twelvemonth old fit adult male ) traveling to West Africa, an country with important hazard of xanthous febrility. From what I could garner there was a “ hard to quantify ” hazard of decease from either giving or non giving the vaccinum. In the terminal I advised the adult male non to hold the vaccinum and to take strict bite turning away safeguards ( which I think is likely the standard advice in a adult male of this age ) . Was this the best determination based on the grounds?

Answer: Dr Grant Dex

I suspect this quandary will be encountered with increasing frequence as retired persons travel to finishs such as The Gambia in hunt of winter Sun. When sing inoculation of travelers who are aged 60 old ages and older, it is indispensable to find whether they will be at hazard for xanthous febrility at their finish, and whether inoculation is required under International Health Regulations.

Since the mid 1990 ‘s studies of terrible neurological and viscerotropic inauspicious reactions following primary xanthous fevervaccination have been reported, peculiarly in the over 60 age group, the hazard increasing with age ( Kitchener 2004 and Khromava et al 2005 ) .

Yellow fever vaccine-associated neurological disease ( YEL-AND ) typically begins 4-27 yearss following inoculation with the oncoming of febrility, concern and confusion, and may include coma, focal neurological shortages or Guillain-Barre syndrome. All instances have occurred in primary vaccinees and most do a complete recovery.A ( Martin et al 2001 )

Yellow fever vaccine-associated viscerotropic disease ( YEL-AVD ) resembles terrible xanthous febrility and is characterised by febrility, unease, concern and multi-organ failure developing within 2-7 yearss of inoculation. All instances have occurred in primary vaccinees, but in contrast to YEL-AND, the mortality rate is over 60 % . ( Chan et al 2001 and Kitchener 2004 )

It is critical that practicians make a careful hazard appraisal prior to administrating the vaccinum. They need to discourse with their patient the hazard of serious unwellness or decease from undertaking xanthous febrility versus the hazard of thevaccine. In general, the WHO advises that the “risk from xanthous febrility for travel to a xanthous febrility endemic part outweighs the hazard associated with the vaccine” , but because of recent studies of decease in unvaccinated travelers and the hazard of terrible inauspicious events following inoculation, physicians should be careful to administrate the vaccinum merely to individuals genuinely at hazard of exposure to yellow febrility.

The absolute hazards have been estimated as follows:

Overall hazard for Serious AEFI A?16 instances per million doses ( lifting to A?53 instances per million doses in the over 60 age group. NNH = 21,780 ( 95 % CI 12,382 – 48,170 )

Hazard for YEL-AND is reported as A?3-5 instances per million doses lifting to A?14-25 instances per million doses in the over 60 age group ; 16 instances worldwide since 1992.

NNH =70,608 ( 95 % CI 27,458 – 657,452 )

Hazard for YEL-AVD is reported as A?3-5 instances per million doses lifting to A?18-25 instances per million doses in over 60 age group ; 36 instances worldwide since 1996.

NNH = 65,340 ( 95 % CI 25, 556 – 4,917,845 ) A ( Cetron et al 2002 ; Kitchener 2004 ; Martin et Al 2001 & A ; Khromava et Al 2005 )

Therefore, the hazard of YEL-AND and YEL-AVD in the over 60 age group additions by a factor of 5-6 or a rate of about one instance per 40,000 doses of xanthous febrility vaccinum administered.

The CDC, Atlanta has estimated the hazard of unwellness and decease duringthe extremum hazard period ( July-October ) in an unvaccinated traveler to West Africa for a 2-week stay as 50 per 100,000 and 10 per 100,000, severally. The hazards of unwellness and decease are 10x greater in West Africa compared toSouth America. In non-immune travelers, the instance mortality can transcend 50 % ( Monath 2004 ) and so of the 6 instances reported among travelers from the US and Europe in 1996-2002, ALL were fatal.

Therefore, in comparative footings, the hazard of terrible unwellness and decease from undertaking xanthous febrility is 20x and 4x greater severally, than the hazard of terrible neurological and viscerotropic inauspicious reactions following primary xanthous fevervaccination in the aged.

Aged travelers who have antecedently been vaccinated for xanthous febrility, but who require a supporter can be reassured that these serious reactions have merely been reported in primary vaccinees without any underlying xanthous febrility unsusceptibility.

Supplying they do non hold a medical contraindication ( e.g. egg allergic reaction or history of Thymus upsets ) , the aged can be administered the vaccinum with minimum hazard. It should besides be borne in head when sing a state where an International Certificate of Vaccination or Prophylaxis ( ICVP ) is a demand for entry, should the traveler decide against inoculation, it is likely that they would be denied entry even with a missive of medical freedom. The lone acceptable contraindications to inoculation are medical conditions, instead than hazard antipathy. Such travelers should be advised to reconsider their travel programs and take an alternate finish.

It is advisable that travelers are vaccinated at least a month before going, leting early acknowledgment and intervention of any inauspicious reactions whilst still in the UK.

In this peculiar instance, Prof Avery advised his patient non to hold the vaccinum and to take mosquito turning away steps. I wonder whether the determination would hold been different if they had been able to establish it on the absolute and comparative hazards of inoculation?

In decision, the current grounds suggests that aged travelers to yellow fever endemic countries should be offered inoculation as this carries a lower hazard of morbidity and mortality than going unvaccinated.