Vaccination options for last-minute travellers in need of travel-related prophylaxis against hepatitis A and B and typhoid fever: a practical guide

A randomized phase 3 trial of the immunogenicity and safety of coadministration of a live-attenuated tetravalent dengue vaccine (TAK-003) and an inactivated hepatitis a (HAV) virus vaccine in a dengue non-endemic country

BACKGROUND

Vaccination against hepatitis A virus (HAV) is largely recommended for travelers worldwide. Concurrent dengue and HAV vaccination may be desired in parallel for travelers to countries where both diseases are endemic. This randomized, observer-blind, phase 3 trial evaluated coadministration of HAV vaccine with tetravalent dengue vaccine (TAK-003) in healthy adults aged 18-60 years living in the UK.

METHODS

Participants were randomized (1:1:1) to receive HAV vaccine and placebo on Day 1, and placebo on Day 90 (Group 1), TAK-003 and placebo on Day 1, and TAK-003 on Day 90 (Group 2), or TAK-003 and HAV vaccine on Day 1, and TAK-003 on Day 90 (Group 3). The primary objective was non-inferiority of HAV seroprotection rate (anti-HAV ≥ 12.5 mIU/mL) in Group 3 versus Group 1, one month post-first vaccination (Day 30) in HAV-naïve and dengue-naïve participants. Sensitivity analyses were performed on combinations of baseline HAV and dengue serostatus. Secondary objectives included dengue seropositivity one month post-second vaccination (Day 120), HAV geometric mean concentrations (GMCs), and safety.

RESULTS

900 participants were randomized. On Day 30, HAV seroprotection rates were non-inferior following coadministration of HAV and TAK-003 (Group 3: 98.7 %) to HAV administration alone (Group 1: 97.1 %; difference: -1.68, 95 % CI: -8.91 to 4.28). Sensitivity analyses including participants who were neither HAV-naïve nor DENV-naïve at baseline supported this finding. Anti-HAV GMCs on Day 30 were 82.1 (95 % CI: 62.9-107.1) mIU/mL in Group 1 and 93.0 (76.1-113.6) mIU/mL in Group 3. By Day 120, 90.9-96.8 % of TAK-003 recipients were seropositive (neutralizing antibody titer > 10) to all four dengue serotypes. Coadministration of HAV vaccine and TAK-003 was well tolerated, with no important safety risks identified.

CONCLUSION

Immune responses following coadministration of HAV vaccine and TAK-003 were non-inferior to administration of HAV vaccine alone. The results support the coadministration of HAV vaccine and TAK-003 with no adverse impact on immunogenicity, safety, and reactogenicity of either vaccine.

CLINICALTRIALS

gov registration: NCT03525119.

Spinning sugars in antigen biosynthesis: characterization of the Coxiella burnetii and Streptomyces griseus TDP-sugar epimerases

The sugars streptose and dihydrohydroxystreptose (DHHS) are unique to the bacteria Streptomyces griseus and Coxiella burnetii, respectively. Streptose forms the central moiety of the antibiotic streptomycin, while DHHS is found in the O-antigen of the zoonotic pathogen C. burnetii. Biosynthesis of these sugars has been proposed to follow a similar path to that of TDP-rhamnose, catalyzed by the enzymes RmlA, RmlB, RmlC, and RmlD, but the exact mechanism is unclear. Streptose and DHHS biosynthesis unusually requires a ring contraction step that could be performed by orthologs of RmlC or RmlD. Genome sequencing of S. griseus and C. burnetii has identified StrM and CBU1838 proteins as RmlC orthologs in these respective species. Here, we demonstrate that both enzymes can perform the RmlC 3'',5'' double epimerization activity necessary to support TDP-rhamnose biosynthesis in vivo. This is consistent with the ring contraction step being performed on a double epimerized substrate. We further demonstrate that proton exchange is faster at the 3''-position than the 5''-position, in contrast to a previously studied ortholog. We additionally solved the crystal structures of CBU1838 and StrM in complex with TDP and show that they form an active site highly similar to those of the previously characterized enzymes RmlC, EvaD, and ChmJ. These results support the hypothesis that streptose and DHHS are biosynthesized using the TDP pathway and that an RmlD paralog most likely performs ring contraction following double epimerization. This work will support the elucidation of the full pathways for biosynthesis of these unique sugars.

The lupus patient traveller: a guide to the rheumatologist

With an increasing number of international journeys occurring daily, there is also an increase in the need for appropriate medical advice for patients who will undertake such travel. In this context, the lupus patient presents a great challenge to the rheumatologist. However, the demand for such information by patients is low, and it has proven difficult for the medical community to adequately provide it. In this article, we carried out a literature review of the medical recommendations made for the lupus patient in order to guide the rheumatologist through the topic of travel medicine.

Characteristics and preparation of the last-minute traveler: analysis of vaccine usage in the Global TravEpiNet Consortium

BACKGROUND

Last-minute travellers (LMTs) present challenges for health care providers because they may have insufficient time for recommended vaccinations or pre-travel preparation. Our objective was to obtain a better understanding of LMTs in order to help travel medicine providers develop improved strategies to decrease the number of LMTs and potentially reduce travel-related morbidity.

METHODS

We defined LMTs as travellers with a departure date of 7 days or fewer from the medical encounter. We analysed the characteristics and health preparation of 12 494 LMTs who presented to a network of US clinical practices for pre-travel health advice between January 2009 and December 2015.

RESULTS

LMTs comprised 16% of all travellers. More LMTs than non-LMTs travelled for business or to visit friends and relatives (VFR) (26% vs 16% and 15% vs 8%, respectively; P < 0.0001). More LMTs also travelled for longer than 1 month (27% vs 21%; P < 0.0001) and visited only urban areas (40% vs 29%; P < 0.0001). At least one travel vaccine was deferred by 18% of LMTs because of insufficient time before departure. Vaccines that required multiple vaccinations, such as Japanese encephalitis and rabies, were the most likely to be deferred because of time constraints.

CONCLUSION

Interventions to improve the timing of pre-travel health consultations should be developed, particularly for business and VFR travellers. Recently endorsed accelerated vaccine schedules for Japanese encephalitis and rabies may help some LMTs receive protection against these infections despite late presentation for pre-travel health care.

Hajj vaccinations-facts, challenges, and hope

Vaccination is an effective preventive measure that has been used in the unique Hajj pilgrimage setting to control the transmission of infectious diseases. The current vaccination policy applied during Hajj is reviewed herein, highlighting the effectiveness of the approaches applied and identifying research gaps that need to be filled in order to improve the development and dissemination of Hajj vaccination strategies.

Counseling for the Wilderness Athlete and Adventurer During a Preparticipation Evaluation for Preparation, Safety, and Injury Prevention

Wilderness sports and adventures continue to increase in popularity. Counseling is an essential element of the preparticipation evaluation (PPE) for athletes in traditional sports. This approach can be applied to and augmented for the wilderness athlete and adventurer. The authors reviewed the literature on counseling during PPEs and gathered expert opinion from medical professionals who perform such PPEs for wilderness sports enthusiasts. The objective was to present findings of this review and make recommendations on the counseling component of a wilderness sports/adventure PPE. The counseling component of a PPE for wilderness sports/adventures should take place after a basic medical evaluation, and include a discussion on sport or activity-specific injury prevention, personal health, travel recommendations, and emergency event planning. Counseling should be individualized and thorough, and involve shared decision making. This should take place early enough to allow ample time for the athlete or adventurer to further prepare as needed based on the recommendations. Resources may be recommended for individuals desiring more information on selected topics.

Counseling for the Wilderness Athlete and Adventurer During a Preparticipation Evaluation for Preparation, Safety, and Injury Prevention

Wilderness sports and adventures continue to increase in popularity. Counseling is an essential element of the preparticipation evaluation (PPE) for athletes in traditional sports. This approach can be applied to and augmented for the wilderness athlete and adventurer. The authors reviewed the literature on counseling during PPEs and gathered expert opinion from medical professionals who perform such PPEs for wilderness sports enthusiasts. The objective was to present findings of this review and make recommendations on the counseling component of a wilderness sports/adventure PPE. The counseling component of a PPE for wilderness sports/adventures should take place after a basic medical evaluation, and include a discussion on sport or activity-specific injury prevention, personal health, travel recommendations, and emergency event planning. Counseling should be individualized and thorough, and involve shared decision making. This should take place early enough to allow ample time for the athlete or adventurer to further prepare as needed based on the recommendations. Resources may be recommended for individuals desiring more information on selected topics.

Epidemiology and prevention of hepatitis A in travelers

BACKGROUND

Hepatitis A is the second most common vaccine-preventable travel-associated infectious disease and hepatitis A virus (HAV) is the most common cause of viral hepatitis. The incidence of infection is closely related to sanitary conditions and the level of economic development.

METHODS

We evaluated HAV incidence, infection-related risk factors, and HAV vaccination rates in international travelers through retrospective analyses using major databases, such as CENTRAL, MEDLINE, EMBASE, and the current literature describing epidemiological data for HAV infection in recent years.

RESULTS AND CONCLUSIONS

We found that the incidence of HAV infection in developed countries is very low. As international travel increases, the incidence of hepatitis A among travelers remains high and likely leads to regional outbreaks. Travelers should visit the Centers for Disease Control and Prevention website or Infectious Disease Prevention Center of their countries to learn about the incidence of infectious diseases associated with their destination before going abroad to determine if they should be vaccinated.

Hepatitis B and C infection in international travelers

BACKGROUND

Hepatitis B and C virus (HBV and HCV) cause significant morbidity and mortality worldwide. With the rise in international travel over the last three decades, many travelers are at risk of HBV and HCV infection.

METHODS

This review focuses on the epidemiology of HBV and HCV in international travelers, the modes of transmission, and the prevention of infection in travelers.

RESULTS

The risk of HBV and HCV infection varies widely and depends on the prevalence of the destination country, the duration of travel, and the activities undertaken while abroad. Travelers commonly undertake high-risk activities that place them at risk of both HBV and HCV infection. Poor uptake of preventative health measures and poor adherence to health recommendations are also common. The monthly incidence of HBV infection for long-term travelers to endemic countries ranges from 25 to 420 per 100,000 travelers. HBV infection can be prevented through timely vaccination of travelers. HBV vaccination is safe and efficacious with protective levels of antibodies achieved in >90% of recipients. Information regarding the risk of HCV acquisition is scarce and until recently was limited to case reports following medical interventions.

CONCLUSIONS

This review demonstrates international travelers are at risk of HBV and HCV infection and provides evidence-based information enabling health practitioners to provide more appropriate pre-travel advice. HBV vaccination should be considered in all travelers to countries with a moderate to high HBV prevalence (HBsAg ≥ 2%) and the risk and benefits discussed with the individuals in consultation with the health practitioner. There is no duration of travel without risk of HBV infection. However, it is apparent that those travelers with a longer duration of travel are at greatest risk of HBV infection (ie, expatriates). Travelers should also receive advice regarding the modes of transmission and the activities that place them at risk of both HBV and HCV infection.

Forecasting dengue vaccine demand in disease endemic and non-endemic countries

BACKGROUND

A dengue vaccine in large-scale clinical trials could be licensed in several years. We estimated the potential vaccine demand for different introduction strategies in 54 dengue-endemic countries and for travelers from non-endemic countries to enable vaccine producers and public health agencies to better prepare for timely utilization of the vaccine.

RESULTS

Under our assumptions, 2.4-3.5 billion dengue vaccine doses would be needed in the first five years after introduction with >75% delivered in the public sector. Among 20 potential 'early-adopter' countries, an estimated 0.9-1.4 billion doses would be needed for the same introduction approach. For the private sector, covering 10% of children and 30% of adults an estimated 443-664 million doses would be required. In non-endemic countries, travelers could use an estimated 59-89 million vaccine doses, although the present product profile would make it unlikely to be able to administer vaccine in a timely manner.

METHODS

Calculations were based on 2015-2020 population projections for endemic countries in Asia and the Americas with populations >100,000. For dengue-endemic countries we assumed country-wide routine 12-23 month-old vaccination and catch-up vaccination among 2-14 year-old children employing a 2 or 3-dose schedule. Assumptions on expected vaccination coverage were based on country-specific public, private and travelers' sectors immunization performance.

CONCLUSIONS

Our results project an upper-limit estimate of vaccine demand, with actual demand depending on country priorities, cost and product profile. Given the potential for a dengue vaccine, policymakers in endemic and nonendemic countries should consider appropriate implementation strategies in advance of licensure.

Should hepatitis B vaccination be introduced into childhood immunisation programmes in northern Europe?

Infection with hepatitis B causes between 500,000 and 1.2 million deaths per year worldwide, and is the leading cause of liver cancer. Over 12 years ago, WHO recommended that universal childhood hepatitis B vaccination be implemented globally. Despite this, Denmark, Finland, Iceland, Ireland, the Netherlands, Norway, Sweden, and the UK have yet to implement such a policy and instead currently adopt an "at-risk" strategy. Although all eight countries are classed as having low endemicity, factors such as increased travel and integration of immigrant communities are increasing the number of at-risk individuals in these countries. Considering the difficulty in identifying all at-risk individuals, and the lack of effectiveness of at-risk vaccination on reducing the overall incidence of hepatitis B, we recommend that these countries reassess their hepatitis B prevention strategies. Universal vaccination against hepatitis B is the only way to eliminate the major public-health impact of this disease.

Vaccinations de l'enfant voyageur

Each year, half a million of children leave France to travel towards countries south or east of the European Union, sometimes in poor sanitary conditions. In order to propose essential or useful immunizations for these trips, the current synthesis will allow the practitioner to insure that the routine French immunization schedule has been followed, and to complete it if needed, to protect the child according to the epidemiological situation in the visited area, to try to reduce the limitations of the immunization of the traveler child. In case of emergency, or close departure, it may be useful to follow an accelerated schedule of the last minute, and, sometimes, to immunize traveler children with a chronic disease. Informations on Internet sites useful for the knowledge of current infectious risks in the destination country are also provided.

Hepatitis A and B Booster Recommendations: Implications for Travelers

Hepatitis A and B are serious vaccine-preventable diseases with a predominantly overlapping epidemiological distribution. Travelers, a term encompassing a range of individuals, are at risk of contracting these diseases if they are unvaccinated. Although the benefits of the primary vaccination course of hepatitis A and B vaccines are clear, the administration of hepatitis A and B boosters varies worldwide. Recommendations on the need for booster vaccinations have recently been published, and the implications of these recommendations for travelers are discussed in this review. Until a greater understanding is reached on the immunogenicity of hepatitis A and B vaccines in certain special groups (e.g., immunocompromised persons), there will be a need to monitor antibody levels to assess whether booster vaccinations are required. However, for the majority of immunocompetent travelers, the full primary vaccination course will provide protection from both hepatitis A and B infection in the long term, without the need for boosters.