Evaluation of rabies immunogenicity and tolerability following a purified chick embryo cell rabies vaccine administered concomitantly with a Japanese encephalitis vaccine

Safety and immunogenicity following co-administration of Yellow fever vaccine with Tick-borne encephalitis or Japanese encephalitis vaccines: Results from an open label, non-randomized clinical trial

BACKGROUND

Flavivirus infections pose a significant global health burden underscoring the need for the development of safe and effective vaccination strategies. Available flavivirus vaccines are from time to time concomitantly delivered to individuals. Co-administration of different vaccines saves time and visits to health care units and vaccine clinics. It serves to provide protection against multiple pathogens in a shorter time-span; e.g., for individuals travelling to different endemic areas. However, safety and immunogenicity-related responses have not been appropriately evaluated upon concomitant delivery of these vaccines. Therefore, we performed an open label, non-randomized clinical trial studying the safety and immunogenicity following concomitant delivery of the yellow fever virus (YFV) vaccine with tick-borne encephalitis virus (TBEV) and Japanese encephalitis virus (JE) virus vaccines.

METHODS AND FINDINGS

Following screening, healthy study participants were enrolled into different cohorts receiving either TBEV and YFV vaccines, JEV and YFV vaccines, or in control groups receiving only the TBEV, JEV, or YFV vaccine. Concomitant delivery was given in the same or different upper arms for comparison in the co-vaccination cohorts. Adverse effects were recorded throughout the study period and blood samples were taken before and at multiple time-points following vaccination to evaluate immunological responses to the vaccines. Adverse events were predominantly mild in the study groups. Four serious adverse events (SAE) were reported, none of them deemed related to vaccination. The development of neutralizing antibodies (nAbs) against TBEV, JEV, or YFV was not affected by the concomitant vaccination strategy. Concomitant vaccination in the same or different upper arms did not significantly affect safety or immunogenicity-related outcomes. Exploratory studies on immunological effects were additionally performed and included studies of lymphocyte activation, correlates associated with germinal center activation, and plasmablast expansion.

CONCLUSIONS

Inactivated TBEV or JEV vaccines can be co-administered with the live attenuated YFV vaccine without an increased risk of adverse events and without reduced development of nAbs to the respective viruses. The vaccines can be delivered in the same upper arm without negative outcome. In a broader perspective, the results add valuable information for simultaneous administration of live and inactivated flavivirus vaccines in general.

TRIAL REGISTRATION

Eudra CT 2017-002137-32.

Safety profile comparison of chimeric live attenuated and Vero cell-derived inactivated Japanese encephalitis vaccines through an active surveillance system in Australia

Limited information is available about post-marketing safety of Japanese encephalitis (JE) vaccines. Using data from SmartVax, an active surveillance system for monitoring vaccine safety, adverse events following immunizations (AEFIs) were compared between the two JE vaccines available in Australia (a chimeric live attenuated vaccine [Imojev] and a Vero cell-derived inactivated vaccine [JEspect]). Data from 2756 patients (1855 Imojev and 901 JEspect) were included. Overall (7.0%), systemic (2.8%), and local (1.9%) AEFIs were uncommon. There were no significant differences in the odds of overall (OR = 1.27; 95%CI: 0.91–1.77), systemic (OR = 1.23; 95%CI: 0.74–2.06), or local (OR = 1.20; 95%CI: 0.65–2.22) AEFIs with Imojev compared to JEspect. There was an increase in odds of overall AEFI in patients aged <5 years (OR = 2.39; 95%CI: 1.10–5.19) compared to those aged >50 years. Both JE vaccines available in Australia are safe and well tolerated. Odds of AEFIs were age-dependent, young children should be carefully observed for AEFIs after vaccination.

Comparison of immunogenicity and safety of licensed Japanese encephalitis vaccines: A systematic review and network meta-analysis

INTRODUCTION

Annually more than 100,000 Japanese encephalitis (JE) cases and 25,000 deaths worldwide are caused by JE virus infection. More than 15 JE vaccines are currently in use worldwide. It is unknown whether any of the vaccines is superior to the others in terms of immunogenicity and safety.

METHODS

Four databases were systematically searched for randomised controlled trials that compared two or more types of JE vaccines. Vaccines were classified into four classes: inactivated mouse brain-derived (oldest class), inactivated Vero cell, live chimeric, and live attenuated. Network meta-analysis was used to generate mixed effect estimates against inactivated mouse brain-derived vaccines for seroconversion, and against placebo for adverse event (AE) and severe adverse event (SAE).

RESULTS

23 studies (38,496 participants) were included. All newer vaccine classes had better immunogenicity, the difference was statistically significant for inactivated Vero cell (OR = 2.98; 95 %CI: 1.02-8.65) and live chimeric (OR = 5.93; 95 %CI: 1.73-20.32) vaccines. Inactivated mouse-derived vaccines had the highest odds for AEs (OR = 2.27; 95 %CI: 1.59-3.23), the odds of AE of newer vaccines was not different to placebo. There was no difference in SAEs across vaccine classes.

CONCLUSIONS

All newer JE vaccines have comparable safety profiles, live chimeric and inactivated Vero cell vaccines are the most immunogenic among the newer vaccine classes.

Japanese Encephalitis Vaccine: Recommendations of the Advisory Committee on Immunization Practices

This report updates the 2010 recommendations from the CDC Advisory Committee on Immunization Practices (ACIP) regarding prevention of Japanese encephalitis (JE) among U.S. travelers and laboratory workers (Fischer M, Lindsey N, Staples JE, Hills S. Japanese encephalitis vaccines: recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR Recomm Rep 2010;59[No. RR-1]). The report summarizes the epidemiology of JE, describes the JE vaccine that is licensed and available in the United States, and provides recommendations for its use among travelers and laboratory workers.JE virus, a mosquitoborne flavivirus, is the most common vaccine-preventable cause of encephalitis in Asia. JE occurs throughout most of Asia and parts of the western Pacific. Approximately 20%-30% of patients die, and 30%-50% of survivors have neurologic, cognitive, or behavioral sequelae. No antiviral treatment is available.Inactivated Vero cell culture-derived JE vaccine (Ixiaro [JE-VC]) is the only JE vaccine that is licensed and available in the United States. In 2009, the U.S. Food and Drug Administration (FDA) licensed JE-VC for use in persons aged ≥17 years; in 2013, licensure was extended to include children aged ≥2 months.Most travelers to countries where the disease is endemic are at very low risk for JE. However, some travelers are at increased risk for infection on the basis of their travel plans. Factors that increase the risk for JE virus exposure include 1) traveling for a longer period; 2) travel during the JE virus transmission season; 3) spending time in rural areas; 4) participating in extensive outdoor activities; and 5) staying in accommodations without air conditioning, screens, or bed nets. All travelers to countries where JE is endemic should be advised to take precautions to avoid mosquito bites to reduce the risk for JE and other vectorborne diseases. For some persons who might be at increased risk for JE, the vaccine can further reduce the risk for infection. The decision about whether to vaccinate should be individualized and consider the 1) risks related to the specific travel itinerary, 2) likelihood of future travel to countries where JE is endemic, 3) high morbidity and mortality of JE, 4) availability of an effective vaccine, 5) possibility (but low probability) of serious adverse events after vaccination, and 6) the traveler's personal perception and tolerance of risk.JE vaccine is recommended for persons moving to a JE-endemic country to take up residence, longer-term (e.g., ≥1 month) travelers to JE-endemic areas, and frequent travelers to JE-endemic areas. JE vaccine also should be considered for shorter-term (e.g., <1 month) travelers with an increased risk for JE on the basis of planned travel duration, season, location, activities, and accommodations and for travelers to JE-endemic areas who are uncertain about their specific travel duration, destinations, or activities. JE vaccine is not recommended for travelers with very low-risk itineraries, such as shorter-term travel limited to urban areas or outside of a well-defined JE virus transmission season.

[What is verified for travel vaccinations?]

Vaccinations are among the most effective preventive measures modern medicine has to offer. They lead both to individual protection in those vaccinated and in many cases to the protection of others against transmission of the infection; however, the acceptance of vaccinations in Germany has declined rather than increased in recent years. Paradoxically, this is very much due to the success of the vaccinations: due to successful immunization campaigns, numerous diseases have become so rare that they have disappeared from the consciousness of the population. Travel medicine counselling offers an excellent opportunity to fill in gaps in immunization.

Adverse events in vaccinations for travelers - a 1-year prospective survey in a travel clinic in Germany

BACKGROUND

The study goal was to assess and compare adverse events (AE) of current vaccinations for travelers under 'real-life conditions'.

METHODS

A prospective observational online questionnaire study was performed from May 2015 till April 2016 in a travel clinic in Germany. Online questionnaire links were sent 1 week after the first vaccination date. Severity was rated on a scale from 1 to 5 (minor to very severe AE).

RESULTS

Of 1357 vaccinees 781 (57.6%) responded to the questionnaire, corresponding to 1415 vaccinations (1-7 simultaneous vaccinations). Responders were more often female (f:m = 1.29:1). Main age groups were 20-29 years old (36.1%). Most frequent vaccinations were against rabies (277; chick embryo cell vaccine (CEC): 97, human diploid cell vaccine (HDC): 180), yellow fever (250), typhoid fever (198), meningococcal meningitis (126) and Japanese encephalitis (104). A total of 217 vaccinees (27.8%) reported AE; 82 (10.5%) rated AE as more severe (grade 3: 61, grade 4: 18, grade 5: 3). No life-threatening AE was reported. Of 157 systemic AE the most frequent were: fatigue (75), headaches (46) and pyrexia (31). Of 94 local AE most frequently reported were pain (66), myalgia (25) and swelling (12). AE after single vaccinations were more often associated with rabies vaccine (OR 2.2; 1.2-4.2). AE increased with the number of simultaneous vaccinations (single vaccination: 24.1%, 88/365; 2 vaccinations: 26.6%, 73/274, ≥3 vaccinations: 39.4%, 56/142, χ2 = 12.24, P = 0.002, CCorr = 0.18), but more severe AE showed no association with the number of vaccinations (χ2 = 5.55, P = 0.06, CCorr = 0.12).

CONCLUSIONS

Single and simultaneous vaccinations were overall well tolerated. AE were reported more frequently with rabies vaccinations in single vaccinations. Increased numbers of simultaneous vaccinations led to some incremental AE but not to more severe AE. Simultaneous vaccinations should be encouraged to reduce missed opportunities for immunizations.

A single center, open label study of intradermal administration of an inactivated purified chick embryo cell culture rabies virus vaccine in adults

In the USA, rabies vaccines (RVs) are licensed for intramuscular (IM) use only, although RVs are licensed for use by the intradermal (ID) route in many other countries. Recent limitations in supplies of RV in the USA reopened discussions on the more efficient use of available biologics, including utilization of more stringent risk assessments, and potential ID RV administration. A clinical trial was designed to compare the immunogenic and adverse effects of a purified chicken embryo cell (PCEC) RV administered ID or IM. Enrollment was designed in four arms, ID Pre-Exposure Prophylaxis (Pre-EP), IM Pre-EP, ID Booster, and IM Booster vaccination. Enrollment included 130 adult volunteers. The arms with IM administration received vaccine according to the current ACIP recommendations: Pre-EP, three 1mL (2.5 I.U.) RV doses, each on day 0, 7, and 21; or a routine Booster, one 1ml dose. The ID groups received the same schedule, but doses administered were in a volume of 0.1mL (0.25 I.U.). The rate of increase in rabies virus neutralizing antibody titers 14-21days after vaccination were similar in the ID and correspondent IM groups. The GMT values for ID vaccination were slightly lower than those for IM vaccination, for both naïve and booster groups, and these differences were statistically significant by t-test. Fourteen days after completing vaccination, all individuals developed RV neutralizing antibody titers over the minimum arbitrary value obtained with the rapid fluorescent focus inhibition test (RFFIT). Antibodies were over the set threshold until the end of the trial, 160days after completed vaccination. No serious adverse reactions were reported. Most frequent adverse reactions were erythema, induration and tenderness, localized at the site of injection. Multi use of 1mL rabies vaccine vials for ID doses of 0.1 was demonstrated to be both safe and inmunogenic.

Pre-exposure rabies prophylaxis: a systematic review

OBJECTIVE

To review the safety and immunogenicity of pre-exposure rabies prophylaxis (including accelerated schedules, co-administration with other vaccines and booster doses), its cost-effectiveness and recommendations for use, particularly in high-risk settings.

METHODS

We searched the PubMed, Centre for Agriculture and Biosciences International, Cochrane Library and Web of Science databases for papers on pre-exposure rabies prophylaxis published between 2007 and 29 January 2016. We reviewed field data from pre-exposure prophylaxis campaigns in Peru and the Philippines.

FINDINGS

Pre-exposure rabies prophylaxis was safe and immunogenic in children and adults, also when co-administered with routine childhood vaccinations and the Japanese encephalitis vaccine. The evidence available indicates that shorter regimens and regimens involving fewer doses are safe and immunogenic and that booster intervals could be extended up to 10 years. The few studies on cost suggest that, at current vaccine and delivery costs, pre-exposure prophylaxis campaigns would not be cost-effective in most situations. Although pre-exposure prophylaxis has been advocated for high-risk populations, only Peru and the Philippines have implemented appropriate national programmes. In the future, accelerated regimens and novel vaccines could simplify delivery and increase affordability.

CONCLUSION

Pre-exposure rabies prophylaxis is safe and immunogenic and should be considered: (i) where access to postexposure prophylaxis is limited or delayed; (ii) where the risk of exposure is high and may go unrecognized; and (iii) where controlling rabies in the animal reservoir is difficult. Pre-exposure prophylaxis should not distract from canine vaccination efforts, provision of postexposure prophylaxis or education to increase rabies awareness in local communities.

Characteristics of Travelers to Asia Requiring Multidose Vaccine Schedules: Japanese Encephalitis and Rabies Prevention

BACKGROUND

Japanese encephalitis (JE) and rabies are serious vaccine preventable diseases which are an important consideration for travelers to Asia.

METHODS

Five Boston-area travel clinics collected demographic data, trip information, and interventions for travelers to Asia seen at pre-travel consultations from March 1, 2008, through July 31, 2010. We evaluated travelers for proportion vaccinated for JE and rabies, those traveling for >1 month, and whether travelers had adequate time to complete the JE series (clinic visit ≥28 days before departure) and rabies pre-exposure prophylaxis (clinic visit ≥21 days before departure).

RESULTS

Among 15,440 travelers from five Boston Area Travel Medicine Network travel clinics, Asia was the most common destination region, visited by 5,582 (36%) of travelers. Among these travelers, 4,810 (86%) planned to travel to only one Asian subregion. Median trip duration was 17 days, with more than 20% traveling for >1 month. The most common destinations were South (41%), Southeast (26%), and East (23%) Asia. Of those traveling to South, Southeast, or East Asia, over one-third with trips >1 month had insufficient time to complete a series for either JE or rabies vaccine. Overall, only 10% of travelers were vaccinated (past and pre-travel visit) for either JE or rabies, with lowest percentages among travelers visiting friends and relatives. Most travelers received advice on vector precautions (96%) and rabies prevention, which included avoiding animal contact, washing wounds, and obtaining appropriate post-exposure prophylaxis (88%).

CONCLUSION

Given the insufficient time for completion and relatively low vaccination rates, greater awareness of earlier pre-travel consultations, at least 4-6 weeks before travel, and accurate risk assessment for travelers are important. Effective counseling about vector avoidance, rabies, and animal bite prevention and management remains critical.