Comparative study of adverse events after yellow fever vaccination between elderly and non-elderly travellers: questionnaire survey in Japan over a 1-year period

A nationwide prospective cohort study on safety of the 17D-204 yellow fever vaccine during a vaccine shortage in Japan

In response to the vaccine shortage of yellow fever vaccine (YF-VAX) due to manufacturing delays, the unapproved 17D-204 YF-VAX was used as an investigator-initiated clinical trial in Japan. The vaccine was administered to 11,279 participants in 19 YF vaccination centers in Japan, and few serious adverse events were observed.

A Systematic Review and a Meta-Analysis of the Yellow Fever Vaccine in the Elderly Population

We conducted a systematic review and a meta-analysis to assess the risk of serious adverse events in the elderly after yellow fever vaccination compared to the non-elderly population. We searched multiple databases and grey literature, and we selected research without language and publication date restrictions. Studies were analyzed in a descriptive way and meta-analyzed and expressed in terms of prevalence ratio and risk ratio with a 95% confidence interval, depending on the degree of heterogeneity found. A total of 18 studies were included and 11 were meta-analyzed. The results obtained through the meta-analysis showed a risk of serious adverse events after yellow fever vaccination three times higher for the elderly when compared to the non-elderly population and five times higher for persons > 70 years. In relation to adverse event types, viscerotropic disease associated with the yellow fever vaccine had a risk that was six times higher when compared to the population < 60 years. The evidence found supports that the vaccine indication in individuals > 60 years of age should be based on a careful analysis of individual benefit-risk assessments. The results found suggest a higher risk of events for individuals > 70 years, especially for viscerotropic and neurotropic disease associated with YFV contraindicating the use of the YFV in this age group.

Early Safety and Tolerability Profile of the BNT162b2 COVID-19 Vaccine in Myasthenia Gravis

Although the COVID-19 vaccines are currently recommended for people with myasthenia gravis (MG), there is no data regarding the safety of the vaccines in this population. In order to investigate the real-life safety data of the BNT162b2 COVID-19 vaccine in people with MG, an anonymous survey was distributed to 142 MG patients. Fifty-six MG patients completed the questionnaire. The median age was 53 years (range 23–83 years); 35 (62.5%) were males, and 25 (44.6%) had associated comorbidities. Thirty-seven participants (66.1%) were treated with immunotherapies. Fifty-five participants (98.2% of the responders) received the BNT162b2 COVID-19 vaccine. Of these, 32 (58.2%) were < 55 years old, and 23 (41.8%) were > 55 years old. Adverse events were more common in patients younger than 55 years old (46.9% Vs. 17.4%; p = 0.0428). Eight participants (14.5%) reported worsening neurological symptoms following the vaccination. Three of those who reported worsening of neurological symptoms (37.5%) required additional treatment. Most events occurred within the first few days after vaccination and resolved within a few weeks. This survey indicates an overall favorable safety and tolerability profile of the BNT162b2 vaccine in people with MG. Additional prospective, large-scale studies are warranted to confirm these findings.

Acceptance of yellow fever vaccine in the older traveller: a cohort study

BACKGROUND AND AIM

Current demographic changes and improvement of quality of life of elderly population have direct consequences on international travelling. The older traveller demands for specific care and precautions to be observed, as for the yellow fever (YF) vaccination, due to the increased incidence rate of adverse events following immunization (AEFI) in people aged 60 years or over. The aim of our study was to determine the adherence to YF vaccine and travel behaviours in a sample of elderly travellers moving to YF endemic areas.

METHODS

Participants in this cohort study were offered YF vaccine, and informed about the increased risk of AEFIs and the unavoidable risk of acquiring YF at the destination. The research was planned on survey-based design, using pre- and post-travel questionnaires.

RESULTS

In 2018, 239 travellers aged 60 years or older attended our travel clinic, of whom 36.8% (n = 88) planned to travel to YF endemic areas and 23.0% (n = 55) for the first time. Of these, 63.6% accepted and 36.4% rejected the vaccination, with 15 travellers moving to endemic areas without immunization, including one patient who presented contraindications to YF vaccine.

CONCLUSIONS

The presence of more than a third of elderly travellers who travelled without vaccination is a substantial public health problem and, since the number of older travellers continues to increase, it becomes necessary to implement robust actions to improve YF vaccine advocacy and adherence.

Patient-reported safety and tolerability of the COVID-19 vaccines in persons with rare neuroimmunological diseases

Background

The COVID-19 vaccines are currently recommended for people with rare neuroimmunological diseases such as neuromyelitis optica spectrum disorder (NMOSD), MOG-antibody disease (MOGAD), and transverse myelitis. However, the safety profile of the vaccines in this population is uncertain.

Objective

To report real-world safety data of the COVID-19 vaccines in persons with rare neuroimmunological diseases.

Methods

An anonymous survey was distributed to patients recruited on social media. Participants answered general demographic and disease-related questions, and specific questions about their experiences with the COVID-19 vaccines.

Results

438 participants completed the questionnaire. The median age was 51 (range 18–82 years); 366 were female (83.6%); 102 (23.3%) had associated comorbidities, and 354 (80.1%) were treated with immunotherapies. 242 participants (55.3%) reported a diagnosis of NMOSD; 99 (22.6%) had MOGAD; 79 (18%) had transverse myelitis. 239 participants (66.2%) were younger than 55 years of age. 138 participants (31.5%) reported earlyadverse events. Of these, 93 (67.4%) were < 55 years old, and 45 (32.6%) were > 55 years old (p=0.0086). The most common adverse events were local reactions, including pain, redness, and swelling at the injection site, reported by 155 participants (35.4%). 73 participants (16.7%) reported new or worsening neurological symptoms following the vaccination. Most symptoms occurred within the first week after vaccination and resolved within three days.

Conclusions

This survey indicates an overall favorable safety and tolerability profile of the COVID-19 vaccines among persons with rare neuroimmunological diseases. Longer-term studies are warranted to confirm these data.

Safety of the BNT162b2 COVID-19 vaccine in multiple sclerosis (MS): Early experience from a tertiary MS center in Israel

Background and purpose

Although the COVID‐19 vaccines are currently recommended for people with multiple sclerosis (MS), the fact that they were not specifically tested in people with MS raises uncertainty regarding their safety in this population. The purpose of this study was to report real‐life safety data of the BNT162b2 COVID‐19 vaccine in a cohort of MS patients.

Methods

An anonymous survey was distributed to 425 MS patients. Participants were asked general demographic and disease‐related questions and specific questions regarding the safety profile of the COVID‐19 vaccine.

Results

Of the 425 MS patients, 262 completed the questionnaire. The median (range) participant age was 42 (22–79) years, 199 participants were women (75.9%), and 66 participants (25.2%) had associated comorbidities. A total of 198 participants (75.6%) were treated with disease‐modifying therapies. In all, 239 participants (91.2% of the responders) had received the BNT162b2 COVID‐19 vaccine. Of these, 182 (76.1%) were aged <55 years, and 57 (23.9%) were aged >55 years. Adverse events were reported by 136 participants (56.9%; 52.5% of those aged <55 years and 40.3% of those aged >55 years; p = 0.1517) and 36 participants (15.1%) reported new or worsening neurological symptoms following the vaccination, the most frequent being sensory disturbances (21 participants, 58.3%). Most symptoms occurred within the first 24 h after vaccination and resolved within 3 days. A total of 28 participants (77.8%) did not require any medication to treat their symptoms.

Conclusions

This survey indicates an overall favorable safety profile of the BNT162b2 vaccine in people with MS. These data should be confirmed in further prospective, large‐scale studies.

This study indicates an overall favorable safety profile of the BNT162b2 COVID‐19 vaccine in people with MS. The spectrum of adverse events reported in our study is comparable to that reported in the general population. Adverse events among MS patients were more frequent in the young‐age group (< 55 years old) compared to individuals older than 55 years old. The overall rate of adverse events may be lower in MS patients treated with DMTs. The rate of new or worsening neurological symptoms is relatively low (15.1%), with most events being of mild severity, not requiring specific treatment, and resolving within a few days.

Vaccines for International Travel

The pretravel management of the international traveler should be based on risk management principles. Prevention strategies and medical interventions should be based on the itinerary, preexisting health factors, and behaviors that are unique to the traveler. A structured approach to the patient interaction provides a general framework for an efficient consultation. Vaccine-preventable diseases play an important role in travel-related illnesses, and their impact is not restricted to exotic diseases in developing countries. Therefore, an immunization encounter before travel is an ideal time to update all age-appropriate immunizations as well as providing protection against diseases that pose additional risk to travelers that may be delineated by their destinations or activities. This review focuses on indications for each travel-related vaccine together with a structured synthesis and graphics that show the geographic distribution of major travel-related diseases and highlight particularly high-risk destinations and behaviors. Dosing, route of administration, need for boosters, and possible accelerated regimens for vaccines administered prior to travel are presented. Different underlying illnesses and medications produce different levels of immunocompromise, and there is much unknown in this discipline. Recommendations regarding vaccination of immunocompromised travelers have less of an evidence base than for other categories of travelers. The review presents a structured synthesis of issues pertinent to considerations for 5 special populations of traveler: child traveler, pregnant traveler, severely immunocompromised traveler, HIV-infected traveler, and traveler with other chronic underlying disease including asplenia, diabetes, and chronic liver disease.

Yellow fever vaccine and risk of developing serious adverse events: a systematic review

Objective

To evaluate contraindications and precautions for the yellow fever vaccine (YFV) in risk populations.

Methods

A literature review was conducted by searching PubMed for “yellow fever vaccine” and “adverse events” (AEs); 207 studies were found, and 43 of them met the inclusion criteria and were included in a systematic review.

Results

The results for first dose of YFV in elderly patients were conflicting—some showed AEs while some showed benefits. Therefore, precaution and case-by-case decisionmaking for YFV in this population are advised. The same precautions are warranted for YFV in infants 6-8 months, with the vaccine contraindicated in those < 6 months old and safe after 9 months of age. YFV seems safe in the first trimester of pregnancy, and probably throughout gestation, as it was not associated with increased malformations. During breastfeeding, YFV continues to be controversial. The vaccine seems safe in people being treated with immunomodulatory or immunosuppressive therapy, people with immunosuppressive diseases, and solid organ and hematopoietic stem cell transplant patients; in stem cell transplants, however, a booster dose should only be applied once immunity is recovered. HlV-infected patients with a CD4+ count > 200 cells/mm³ do not have increased risk of AEs from YFV. Egg allergy vaccination protocols seem to provide a safe way to immunize these patients.

Conclusions

YFV safety has been confirmed based on data from many vaccination campaigns and multiple studies. AEs seem more frequent after a first-time dose, mainly in risk groups, but this review evaluated YFV in several of the same risk groups and the vaccine was found to be safe in most of them.

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.

Screening test for neutralizing antibodies against yellow fever virus, based on a flavivirus pseudotype

Given the possibility of yellow fever virus reintroduction in epidemiologically receptive geographic areas, the risk of vaccine supply disruption is a serious issue. New strategies to reduce the doses of injected vaccines should be evaluated very carefully in terms of immunogenicity. The plaque reduction test for the determination of neutralizing antibodies (PRNT) is particularly time-consuming and requires the use of a confinement laboratory. We have developed a new test based on the use of a non-infectious pseudovirus (WN/YF17D). The presence of a reporter gene allows sensitive determination of neutralizing antibodies by flow cytometry. This WN/YF17D test was as sensitive as PRNT for the follow-up of yellow fever vaccinees. Both tests lacked specificity with sera from patients hospitalized for acute Dengue virus infection. Conversely, both assays were strictly negative in adults never exposed to flavivirus infection or vaccination, and in patients sampled some time after acute Dengue infection. This WN/YF17D test will be particularly useful for large epidemiological studies and for screening for neutralizing antibodies against yellow fever virus.