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No Booster Dose for Yellow Fever Vaccination: What Are the Consequences for the Activity of Vaccination in Travel Clinics? Benjamin Wyplosz, MD, PhD,∗ Jean-Philippe Leroy, MD,† Ouda Derradji, MD,∗ and Paul-Henri Consigny, MD‡ ∗
Assistance publique-hôpitaux de Paris, CHU de Bicêtre, Service des maladies infectieuses et tropicales, Centre de vaccinations internationales, Le Kremlin-Bicêtre, France; † CHU de Rouen, Centre de vaccinations internationales, Rouen, France; ‡ Institut Pasteur, Centre Médical, Clinique du voyage, Centre d’Infectiologie Necker-Pasteur, Paris, France DOI: 10.1111/jtm.12173
Y
ellow fever (YF) vaccine is required or recommended for people aged ≥9 months who are traveling to or living in areas at risk for YF virus transmission.1 YF vaccination is regulated by Annex 7 of the International Health Regulations (IHR).2 Historically, immunization requires a single dose administered subcutaneously with booster doses at 10-year intervals. As proof of receipt of YF vaccine, all vaccines should possess an International Certificate of Vaccination (ICV) provided by an approved YF vaccination center. The ICV is regulated by Annex 6 of the IHR.2 Travelers who arrive in a country with a YF vaccination entry requirement without a valid ICV may be quarantined, denied entry, or possibly revaccinated at the point of entry. In April 2013, the Strategic Advisory Group of Experts (SAGE) on immunization stated that a single dose of YF vaccine is sufficient in the general population to confer a lifelong protection against YF.3 The SAGE also pointed out that specific risk groups, such as infants Corresponding Author: Benjamin Wyplosz, MD, PhD, CHU Bicêtre, Service des maladies infectieuses et tropicales, Centre de vaccinations internationales, 78 rue du général Leclerc, Le Kremlin-Bicêtre F-94275, France. E-mail: ben
[email protected] © 2014 International Society of Travel Medicine, 1195-1982 Journal of Travel Medicine 2015; Volume 22 (Issue 2): 140–141
or immunocompromised patients, might benefit from a second primary dose, a booster dose, or a serology monitoring. The WHO World Health Assembly in May 2014 adopted an amendment to Annex 7 of the IHR (2005), which stipulates that the period of protection afforded by YF vaccination, and the term of validity of the certificate will change from 10 years to lifetime of the person vaccinated. This change will enter into force legally in June 2016.4 Thus, among the 63 countries endemic for YF, 21 countries require a valid ICV for travelers coming from all countries, while 42 countries do not require a proof of YF vaccination as a condition for entry.2 As a consequence to the amendment of Annex 7 of the IHR, travelers visiting most YF-endemic countries requiring a YF ICV at entry will not need to receive a booster dose of YF at 10 years and their ICV will remain valid for lifetime. It should be noted that a few countries may express reservation on or even reject the amendment in the next few months and still require vaccination booster at 10 years. The objective of this prospective study was to determine the potential impact of the SAGE recommendations on the vaccination activity of our travel clinics.
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In April 2013, the Strategic Advisory Group of Experts (SAGE) on immunization stated that a single dose of yellow fever (YF) vaccine is sufficient in the general population to confer a lifelong protection against YF. When the period of validity of the International Certificate of Vaccination (ICV) will be extended to a lifetime in June 2016, no booster dose will be needed. The objective of this prospective study was to determine the potential impact of the SAGE recommendations on the vaccination activity of our travel clinics. We showed that among 1,037 subjects seen in our three travel clinics for a YF vaccination in 2013, about 32.3% went for a booster dose that is no longer useful according to the SAGE. A drop in vaccination activity has to be expected by travel clinics in the next years, and changes in daily exercise have to be anticipated, as YF vaccination is a large part of the regular work of many healthcare providers specialized in travel medicine.
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Yellow Fever Booster Doses in Travel Clinics Table 1
Distribution of 1,037 subjects visiting our travel clinic for a YF vaccination before traveling to a YF-endemic country Primary vaccination
Booster dose
Valid yellow fever (YF) international certificate Travel clinic Institut Pasteur (n = 828) Bicêtre (n = 81) Rouen (n = 128) Total (n = 1,037)
Required* N (%) 340 (41.0) 40 (49.3) 38 (29.7) 418 (40.3)
Not required† N (%) 214 (26.0) 14 (17.3) 56 (43.8) 284 (27.4)
Required* N (%) 220 (26.5) 23 (28.4) 22 (17.2) 265 (25.5)
Not required† N (%) 54 (6.5) 4 (5) 12 (9.4) 70 (6.8)
*The 20 YF-endemic countries requiring a valid international certificate are as follows: Angola, Benin, Burkina Faso, Burundi, Cameroon, Central African Republic, Congo, Côte d’Ivoire, French Guyana, Gabon, Ghana, Guinea-Bissau, Liberia, Mali, Niger, Democratic Republic of the Congo, Rwanda, São Tomé et Príncipe, Sierra Leone, and Togo. †The 43 YF-endemic countries not requiring a valid YF certificate are listed in Ref (3).
Methods
Results During the 1-week study period in June 2013, 1,037 subjects were seen in our three travel clinics for a YF vaccination. The proportion of travelers consulting for a primary vaccination or a booster dose according to each group of YF-endemic country was similar for the three study centers (Table 1). Overall, 6.8% of travelers were seen in consultation for a booster dose that need not be administered according to the new SAGE recommendations. We have calculated that if the period of validity for ICV against YF was extended lifelong in the IHR, 25.5% of travelers (for a total of 32.3%) consulting in our travel clinics should not need to be vaccinated.
Acknowledgments The authors are indebted to Drs Patrick Besnoit, Marie Becchio, Caroline Fontaine, Florence Guillemot, Luu-Ly Pham, and Mr Laurent Tzara (CHU de Bicêtre); the medical and nursing staff of the Centre médical de l’Institut Pasteur who recorded the data; and Drs Daniel Vittecoq (CHU de Bicêtre) and Stella Lee (Harvard Medical School) for reviewing our manuscript. Declaration of Interests The authors state that they have no conflicts of interest to declare.
Discussion
References
To the best of our knowledge, this is the first study to evaluate the impact of the new SAGE recommendations not to provide booster doses of YF vaccine. We showed that these recommendations may have an immediate impact on the activity of our travel clinics, as 6.8% of travelers had no medical reason or immunization requirement to receive a booster dose of YF vaccination. We have evaluated that if the period of validity of ICV is extended to lifetime, the YF vaccination activity of our travel clinics will drop by 32.3%. This study has several limitations. First, we did not ask travelers whether they would have gone to a travel clinic (for travel advice, another immunization, or an
1. Centers for Disease Control and Prevention. Yellow fever vaccine. Morbid Mortal Wkly Rep 2010; 59:RR-7. 2. World Health Organization, ed. International health regulations (2005). 2nd Ed. Geneva: WHO Library, 2008. Available at: http://www.who.int/ihr/publications/9789241 596664/en/ (Accessed 2014 Oct 22) 3. Strategic Advisory Group of Experts on Immunization. Meeting of the Strategic Advisory Group of Experts on immunization, April 2013—conclusions and recommendations. Wkly Epidemiol Rec 2003; 88: 201–6. 4. World Health Organization. Yellow fever vaccination booster. Geneva: WHO, 2014. Available at: http://www. who.int/ith/updates/20140605/en/. (Accessed 2014 Oct 22). J Travel Med 2015; 22: 140–141
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We systematically recorded the type of vaccination (primary or booster dose) and the destination of all subjects seen in consultation for a YF vaccination in our travel clinics (Centre médical de l’Institut Pasteur, Centre de vaccinations internationales du CHU de Bicêtre, Centre de vaccinations internationales du CHU de Rouen). We classified patients according to destination: (1) the 20 YF-endemic countries requiring a valid ICV for travelers from all countries for entry and (2) the 43 YF-endemic countries not requiring a valid ICV.
antimalarial prescription) had they known that a YF booster was not required. Second, this study was conducted only in France where the proportion of travelers needing a booster dose of YF vaccine may differ from other countries. Third, we studied only 1,037 patients, but the study period was in June, which is the busiest month for YF vaccination before summer holidays and mostly representative of YF vaccine practices. In conclusion, the extension of the period of validity of the YF vaccine to lifetime is expected to have a substantial impact on the activity of the travel clinics in France, which should be anticipated.