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Yellow fever virus is an arbovirus transmitted to humans by Aedes and Haemogogus mosquito species. To date, there is no specific treatment for yellow fever. However, an effective vaccine is available for the prevention. After a decline in yellow fever cases in Africa between 2004 and 2015, large-scale transmission of the virus was observed in Africa during 2019, with outbreaks recorded in West Africa. The objective of this study was to estimate the incidence of yellow fever cases recorded in the national reference laboratory of Togo from 2010 to 2020.Data were extracted from the National Institute of Hygiene database from 2010 to 2020 with an Excel sheet and descriptive analyses were performed.A total of 4350 samples were collected between 2010 and 2020 in Togo from yellow fever suspected cases. These cases had a median age of 12 years (IQR: 5-24), and 21% of them were from the Maritime region. Among them, 30 cases were reported by national laboratory, with a global incidence of 0.7% (confidence interval 95%: [0.4-1.0]). At the yellow fever regional laboratory, 14 cases were confirmed with an incidence of 0.33% (confidence interval 95%: [0.18-0.55]). In this population, 37.7% had been immunized against yellow fever.This study shows that Togo presents cases of yellow fever. Identification of the vectors and implementation of efficient vector control measures could help prevent this disease, as well as other diseases transmitted by the same vectors. Yellow fever vaccination should be a priority in vaccination programs.

Yellow fever (YF) vaccination is the single most important preventative measure against YF infection, however the live attenuated vaccine has associated serious adverse events. All YF vaccinations in England, Wales and Northern Ireland (EWNI) are administered in YF Vaccination Centres and comply with National Travel Health Network and Centre (NaTHNaC) Conditions of Designation and Code of Practice, including reporting of vaccine incidents to NaTHNaC. In this study we evaluated the number and type of YF vaccine incidents in EWNI to identify areas for improvement.NaTHNaC's telephone advice line database was retrospectively searched from 1st January 2016 to 31st December 2018 for YF vaccine incidents. Calls were categorised and analysed according to incident type.Seventy-eight YF vaccine incidents were reported from a total of 17250 calls. The commonest incident was incorrect timing of measles, mumps and rubella vaccine in relation to YF vaccine, where the recommended 28-day interval was not observed (n = 21). Other incidents included accidental partial vaccination (n = 11), inappropriate vaccination (n = 5) and invalid vaccination due to expiry or cold chain breach (n = 4). Inadvertent vaccination in contraindicated individuals occurred in two travellers with thymectomies (resulting in one death), and five immunocompromised travellers.YF vaccine incidents represent a small proportion of total calls. Similar incidents likely occur with other vaccines, but YF vaccine incidents are of particular concern; whilst most incidents were not harmful, vaccination in contraindicated individuals resulted in one death. These findings helped to inform new guidance and update training for staff in YF vaccination centres.

Background We study the association between prior yellow fever immunization and clinical outcomes of dengue infections in individuals of varying sexes and ages. Serological interactions between dengue virus and other flaviviruses could drive antibody dependent enhancement, which is associated with disease severity in dengue infections. This effect may influence disease severity in individuals subsequently affected by related flaviviruses, such as dengue. We compare the severity of dengue episodes between patients vaccinated and non-vaccinated against yellow fever. Methods We evaluated the severity of 11,448 lab-confirmed dengue cases reported in Sao Jose do Rio Preto, Brazil, in 7370 YF vaccinated patients compared to 4043 unvaccinated patients. We regressed dengue severity against YF vaccine status and a number of demographic, clinical, and laboratory variables as controls. We also evaluated the association between YF vaccination status and the clinical and laboratory symptoms of dengue patients. Results We did not find any evidence of increased risk for severe dengue in patients vaccinated against YF (odds ratio = 1.00; 95% confidence interval = 0.87–1.14). Most of the variables analyzed did not have a statistically significant association with YF vaccination status. Conclusions We found no evidence that YF vaccination in dengue-endemic areas increases the risk of severe dengue fever.

Minist?rio da Sa?de. Secretaria de Vigil?ncia em Sa?de. Instituto Evandro Chagas. Ananindeua, PA, Brasil / Universidade Federal do Par?. Faculdade de Medicina. Bel?m, PA, Brazil. Hospital de Infecciosas F. Mu??z. Buenos Aires, Argentina. Scientific Affairs and Public Health Medical Director for GSK Vaccines inLatin America. Buenos Aires, Argentina. Hospital de Trauma y Emergencias. Federico Abete, Buenos Aires, Argentina. Hospital Brit?nico de Buenos Aires?. Buenos Aires, Argentina. Universidad Central de Venezuela. Faculty of Medicine. Caracas, Venezuela. Pontificia Universidad Cat?lica de Chile. School of Medicine. Department of Pediatric Infectious Diseases and Immunology. Santiago de Chile, Chile. Hospital de Infecciosas F. Mu??z. Buenos Aires, Argentina Universidad Tecnol?gica de Pereira. Faculty of Health Sciences. Public Health and Infection Research Group. Pereira, Risaralda, Colombia / UniFranz. Faculty of Health Sciences. Medical School. Cochabamba, Bolivia. Hospital de Infecciosas F. Mu??z. Buenos Aires, Argentina.

Instituto de Ciencias e Innovacion en Medicina (ICIM)/ Centro de Epidemiologia y Politicas de Salud

Summary Background The Department of Health regulates the designation of yellow fever vaccination centres (YFVCs) in the Republic of Ireland to ensure appropriate standards in the safe, effective use of yellow fever vaccine for overseas travellers. The process of designation of YFVCs is delegated to Directors of Public Health who direct Principal Medical Officers. Variation in implementation of specific criteria for designation exists and no formal follow up inspection is carried out. This survey of all designated YFVCs in the Republic of Ireland aimed to assess compliance with standards to ensure the objectives of the national yellow fever vaccination programme were met. Methods A piloted questionnaire devised from a United Kingdom (UK) YFVC survey was developed and tested in five YFVCs. The questionnaire was adapted for the postal survey and captured data on professional training, reference sources, services provided, physical facilities and supplies, and was distributed to 655 YFVCs in a stamped addressed envelope. Results During the period 2010–2011, there were 655 designated YFVCs in the Republic of Ireland. Responses were received from 246 centres (38% response rate), 91% of which were in general practice. Deficiencies were identified in respect of vaccine refrigeration protocols, record keeping, attendance at YFVC training sessions, and clinical protocols for adverse events. Conclusions Specific deficiencies in relation to training, vaccine storage, administration and documentation should be addressed to ensure standardised YFVC practices and thus align them with best international practice.

Analyze the impact of educational level, negative beliefs and negative attitudes on the yellow fever vaccination coverage (YFVC).This analytical study involved a sample of 2763 people from 866 households. Educational status was described in six levels: No level (Respondent had never attended school), level-1 (respondent left before intermediate school), level-2 (Respondent attended intermediate school), level-3 (respondent attended high school), level-4 (Respondent attended university), Other level (When the level could not be determined). The Attitude towards vaccination was described in terms of person's availability to recommend vaccination to third. The relationships were analyzed by multivariate mixed logistic regression.Among the 2763 peoples, 2039 (73.8%) were vaccinated against yellow fever. People who left high school with or without the French baccalaureate were more likely to be vaccinated against YF than people without any diploma (OR = 1.4; p 0.05). The probability of being vaccinated among people with negative attitudes was reduced by 40% (OR = 0.6; p 0.05).Low level of education, negative beliefs and negative attitudes have significant impacts on YFVC. Negatives beliefs and attitudes result often from a major lack of information about the benefits of vaccination. This deficit is exacerbated in persons with low educational level.

Summary Background Vulnerable individuals such as elderly, children/adolescents and pregnant/breastfeeding women increasingly travel overseas. We describe the travel and vaccination patterns of these groups at the largest Travel Clinic in Switzerland especially focusing on travel to yellow fever and malaria-endemic countries, and yellow fever vaccination (YFV) and malaria medications. Method An analysis of pre-travel visits between 2010 and 2012 at the Travel Clinic of the University of Zurich, was performed assessing differences between the elderly, young and middle-aged travelers as well as between pregnant/breastfeeding and other female travelers. Results Overall, the vulnerable groups did not differ from other travelers regarding their travel patterns. YFV was the most often administered vaccine to elderly travelers; half of them received it for the first time. More than 30% of children/adolescents received YFV, but no child below six months was vaccinated. 80% of young travelers and a similar percentage of pregnant women went to malaria-endemic regions. Twenty-five pregnant/breastfeeding women traveled to YF endemic areas. Conclusions Travel patterns of vulnerable travelers are comparable to those of other travelers. In view of the limited data on malaria medications and precautions against YFV during pregnancy and at the extreme ages of life, giving travel advice to these groups is challenging.

Guidelines issued by the WHO call for immunization against yellow fever (YF) at least 10 days before entering an endemic area. We assessed the extent at which travelers complied with these guidelines.A two-phase study at one travel center in Israel. Phase I-travelers planning to visit YF-endemic areas (n = 295) were evaluated in regard to the timing of administration of YF vaccine before travel. Phase II-the specific causes of arriving late were studied prospectively in another group of 132 travelers.Phase I-one-half of the travelers (n = 148) headed to South America (SA), and 147 to Africa. The mean age (+/-SD) of this cohort was 30.9 (+/-14.9) years (range 6-75 years). Overall, 64 (21.7%; 95% confidence interval, 17.4-26.8) received the vaccine less then 10 days before departure. However, only 10.8% of those heading to SA arrived late, as compared to 32.7% of those heading to Africa (p0.0001). Phase II-a last minute's decision was the commonest reason given for arriving late (43.2%).One-fifth of travelers fail to comply with the WHO guidelines concerning YF vaccination. Travelers and travel agents alike need to be reminded of the importance of timely vaccination against YF.

Yellow fever is a mosquito-borne disease, which can cause serious illness. The World Health Organization (WHO) requires travellers to have vaccination against Yellow fever for all international travel going into and from Yellow fever endemic areas in order to prevent the spread of this potentially deadly disease. Only clinics and hospitals authorised by health departments of national governments can administer the disease. Yellow fever vaccination centres are often subject to inspection in many countries, although the requirements for Yellow fever vaccinators (YFV) vary from country to country. In New Zealand, approval of YFV now requires specific postgraduate training in travel medicine or its equivalent, as well as continuing professional development to maintain this status. It is expected that this will assist in improving standards of travel medicine practice in New Zealand.

In March 2013, the World Health Organization (WHO) Strategic Advisory Group of Experts on Immunisation (SAGE) considered a number of issues in order to update the WHO Position Paper on Yellow Fever (2003). A key conclusion of this review was that a single dose of yellow fever (YF) vaccine appears to confer life-long protection against YF disease, and that a booster dose of YF vaccine is not needed to maintain immunity. While the efficacy of YF vaccine in the majority of vaccine recipients is not in doubt, the WHO announcement is somewhat surprising as there are some limitations in the evidence base, but more importantly, this announcement is not accompanied by any imminent change in the International Health Regulations 2005. The tension between what is considered best clinical practice and the law will be difficult to reconcile for many health professionals, travellers, and the travel industry, in an area of travel medicine that is already subject to debate and confusion. This commentary reviews the recent WHO announcement, and considers the practical implications for health professionals providing YF vaccine to international travellers.

Summary The purpose of this prospective, questionnaire-based study is to assess pre-travel vaccinations and malaria prophylaxis for long-term travellers who receive pre-travel advice in Greece. A total of 4721 travellers were studied from January 1, 2009 through December 31, 2012. Travellers sought pre-travel advice at a mean of 19.7 days (range: 0–349 days) before departure. Long-term travellers (≥1 month) accounted for 2205 (46.7%) of all travellers. Long-term travellers had a mean age of 34.5 years. The majority of them were men (79.8%). In terms of destinations, 84% were visiting malaria-endemic countries and sub-Saharan Africa was the most common destination (17.7%). Most long-term travellers pursued trips for work purposes (70%), visited urban areas (79.6%) and stayed in hotels (29.2%). Yellow fever, typhoid fever, hepatitis A and tetanus/diphtheria vaccines were administered to 1647 (74.7%), 741 (33.6%), 652 (29.5%), and 589 (26.7%) travellers, respectively. Yellow fever vaccine was administered to 339 (87%) and 132 (71%) of long-term travellers to sub-Saharan Africa and South America respectively, whereas typhoid vaccine to 119 (90.8%) and 330 (84.6%) of those travelling to the Indian subcontinent and sub-Saharan Africa respectively. Rabies vaccine was administered to 14 (0.6%) of them. Malaria prophylaxis was recommended to 446 (20%) of long-term travellers. Mefloquine was the most commonly (49%) prescribed agent, and was prescribed to 26.7% of long-term travellers to sub-Sahara Africa. In conclusion, this study revealed that recommendations for vaccine and malaria prophylaxis for long-term travellers to developing countries should be more selective, based on the assessment of all travellers' and travel characteristics, in order to provide adequate pre-travel preparation for this high risk group of travellers. More focused studies are suggested in order to understand the particular needs of long-term travellers. Increasing awareness of travellers and travel health consultants is very important.

Mandatory visits to immunization centers that offer pre-travel Yellow fever vaccine to prospective travelers would be useful for briefing the basics of the biology of the mosquito responsible for Yellow fever spread. Pre- travel knowledge on the day-time rather the nocturnal biting habit of the mosquitoes of Aedes species would prevent from bites of the mosquitoes responsible for the spread of viruses causing Yellow fever, dengue or Chikungunya infection.