Vaccine safety

Investigating safety profiles of human papillomavirus vaccine across group differences using VAERS data and MedDRA

Background

The safety of vaccines is a critical factor in maintaining public trust in national vaccination programs. This study aimed to evaluate the safety profiles of human papillomavirus (HPV) vaccines with regard to the distribution of adverse events (AE) across gender and age, and the correlations across various AEs using the Food and Drug Administration/Centers for Disease Control and Prevention Vaccine Adverse Event Reporting System (VAERS).

Methods

For analyses, 27,348 patients aged between 9 and 25 years old with at least one AE reported in VAERS between the year of 2006 and 2017 were included. AEs were summarized into two levels: the lower level preferred term (PT) and higher level system organ classes (SOCs) based on the structure of Medical Dictionary for Regulatory Activities (MedDRA). A series of statistical analyses were applied on both levels of AEs. Zero-truncated Poisson regression and multivariate logistic regression models were first developed to assess the rate and risk of SOCs across age groups and genders. Pairwise Pearson correlation analyses and hierarchical clustering analyses were then conducted to explore the interrelationships and clustering pattern among AEs.

Results

We identified 27,337 unique HPV vaccine reports between 2006 and 2017. Disproportional reporting of AEs was observed across age and gender in 21 SOCs (p < 0.05). The correlation analyses found most SOCs demonstrate weak positive correlations except for five pairs which were negatively correlated: skin and subcutaneous tissue disorders + injury poisoning and procedural complications; skin and subcutaneous tissue disorders + nervous system disorders; Skin and subcutaneous tissue disorders + pregnancy, puerperium and perinatal conditions; nervous system disorders + pregnancy, puerperium and perinatal conditions; pregnancy, puerperium and perinatal conditions + general disorders and administration site conditions. Nervous system disorders had the most AEs which contributed to 12,448 (46%) cases. In the further analyses of correlations between PT in nervous system disorders, the three most strongly correlated AEs were psychiatric disorders (r = 0.35), gastrointestinal disorders (r = 0.215), and musculoskeletal and connective tissue disorders (r = 0.261). We observed an inter-SOCs correlation of the PTs among AE pairs by nervous system disorders/psychiatric disorders/gastrointestinal disorders/musculoskeletal and connective tissue disorders.

Conclusions

The analyses revealed a different distribution pattern of AEs across gender and age subgroups in 21 SOC level AEs. Correlation analyses and hierarchical clustering analyses further revealed several correlated patterns across various AEs. However, findings from this study should be interpreted with caution. Further clinical studies are needed to understand the heterogeneity of AEs reporting across subgroups and the biological pathways among the statistically correlated AEs.

Influenza vaccines: Evaluation of the safety profile

The safety of vaccines is a critical factor in maintaining public trust in national vaccination programs. Vaccines are recommended for children, adults and elderly subjects and have to meet higher safety standards, since they are administered to healthy subjects, mainly healthy children. Although vaccines are strictly monitored before authorization, the possibility of adverse events and/or rare adverse events cannot be totally eliminated. Two main types of influenza vaccines are currently available: parenteral inactivated influenza vaccines and intranasal live attenuated vaccines. Both display a good safety profile in adults and children. However, they can cause adverse events and/or rare adverse events, some of which are more prevalent in children, while others with a higher prevalence in adults. The aim of this review is to provide an overview of influenza vaccine safety according to target groups, vaccine types and production methods.

Near real-time vaccine safety surveillance using electronic health records-a systematic review of the application of statistical methods

PURPOSE

Pre-licensure studies have limited ability to detect rare adverse events (AEs) to vaccines, requiring timely post-licensure studies. With the increasing availability of electronic health records (EHR) near real-time vaccine safety surveillance using these data has emerged as an option. We reviewed methods currently used to inform development of similar systems for countries considering their introduction.

METHODS

Medline, EMBASE and Web of Science were searched, with additional searches of conference abstract books. Questionnaires were sent to organizations worldwide to ascertain unpublished studies. Eligible studies used EHR and regularly assessed pre-specified AE to vaccine(s). Key features of studies were compared descriptively.

RESULTS

From 2779 studies, 31 were included from the USA (23), UK (6), and Taiwan and New Zealand (1 each). These were published/conducted between May 2005 and April 2015. Thirty-eight different vaccines were studied, focusing mainly on influenza (47.4%), especially 2009 H1N1 vaccines. Forty-six analytic approaches were used, reflecting frequency of EHR updates and the AE studied. Poisson-based maximized sequential probability ratio test was the most common (43.5%), followed by its binomial (23.9%) and conditional versions (10.9%). Thirty-seven of 49 analyses (75.5%) mentioned control for confounding, using an adjusted expected rate (51.4% of those adjusting), stratification (16.2%) or a combination of a self-controlled design and stratification (13.5%). Guillain-Barré syndrome (11.9%), meningitis/encephalitis/myelitis (11.9%) and seizures (10.8%) were studied most often.

CONCLUSIONS

Near real-time vaccine safety surveillance using EHR has developed over the past decade but is not yet widely used. As more countries have access to EHR, it will be important that appropriate methods are selected, considering the data available and AE of interest.

Addressing parents' concerns about childhood immunizations: a tutorial for primary care providers

BACKGROUND

Despite the dangers of vaccine-preventable infections and efforts by health care professionals to promote immunization, parents' resistance to routine childhood immunizations continues to grow. This phenomenon can give rise to frustration among health care providers, as well as create barriers in providing medical care to children in need. In response, we developed a CD-ROM-based tutorial that (1) explains the nature and origins of parents' concerns, (2) addresses clinical implications of resistance to immunization, (3) explores ethical and professional obligations that physicians have toward children and their parents, and (4) discusses how physicians can effectively address parents' concerns.

OBJECTIVE

Our goals were to evaluate the tutorial's effectiveness in improving physicians' (1) general knowledge about parents' resistance to childhood immunizations, (2) knowledge of adverse effects of immunization, and (3) attitudes toward parents' resistance to childhood immunization.

DESIGN/METHODS

After pretesting, expert review, and revision, the 45-minute Penn State Immunization Project tutorial was pilot tested with pediatric and family medicine residents at 7 training programs in 4 states (Pennsylvania, New York, Maryland, and Iowa). Knowledge and attitudes were assessed by using a 26-item pretest/posttest, the results of which were then analyzed by using standard statistical methods.

RESULTS

A total of 122 residents completed the pretest/posttest. Statistically and clinically significant improvements were seen in residents' general knowledge, knowledge of adverse events, and all 5 attitudinal measures regarding childhood immunizations.

CONCLUSIONS

The tutorial Addressing Parents Concerns About Childhood Immunizations: A Tutorial for Primary Care Providers is effective in improving resident physicians' general knowledge, knowledge of adverse events, and attitudes. As such, this tutorial has the potential to enhance communication between parents and primary care providers and, more generally, improve clinicians' response to the growing resistance toward routine childhood immunizations.

Actions and Beliefs Related to Hepatitis B and Influenza Immunization Among Registered Nurses in Texas

Studies indicate that roughly half of health care workers are not immunized against hepatitis B and influenza. Findings from a survey of 1,000 registered nurses (RNs) conducted to analyze their beliefs and actions related to immunization recommendations are reported. Only 8% of the responding RNs chose not to receive vaccination against hepatitis B. The primary reasons that nurses declined hepatitis B vaccination were because they were not working in nursing or did not believe they were at risk of exposure. Similarly, 86% of the RNs reported they had ever received a flu shot, and 69% reported of being immunized during 2 of the previous 4 years. Rationale for receiving immunization included belief in its effectiveness, belief that they were at risk of exposure, and that it was provided free of charge. Reasons for declining included concerns about side effects, lack of concern about getting the illness, and doubts about effectiveness. The nurses who responded to the survey appear to value immunizations and generally adhere to immunization recommendations. Further study needs to be conducted on related issues, including follow-up for assessment of long-term protection of hepatitis B immunization and adherence to guidelines for postexposure prophylaxis. Ongoing monitoring and further study of serious complications of hepatitis B immunizations are also needed.

Could It Happen Here? Vaccine Risk Controversies And The Specter Of Derailment

Controversy over vaccine safety has achieved high visibility over the past decade. At the same time, however, levels of coverage for routinely recommended childhood vaccines in the United States are at their highest ever. We examine this apparent paradox. We consider the ways in which concerns over vaccine safety have emerged and diffused through the popular media, legislative hearings, and Internet-based activism. As a case study, we review the controversy over the alleged connection between autism and the measles-mumps-rubella (MMR) vaccine and consider why it had a dramatic effect on the vaccine's acceptance in Great Britain but virtually none in the United States.

Non-clinical vaccine safety assessment

As vaccines are undoubtedly classified as pharmaceuticals, they have to be submitted to strict non-clinical safety evaluation. The context of their prophylactic use requires that every effort is made to ensure their safe use. Their safety evaluation is complex as they act through a multistage mechanism in which the vaccine by itself acts as a pro-drug, antibodies and activated lymphocytes being the actual effectors. Therefore, several potential toxicities must be considered: direct toxicity of the test article, toxicity linked to the pharmacodynamic activity of the vaccine, activation of pre-existing disorders, toxicity of contaminants and impurities and other adverse reactions due to interaction between the various components. Guidelines dealing with vaccines include general guidelines applicable to all pharmaceuticals, such as ICH S6, and also more specific documents which allow some flexibility in study design. Among the various studies, if single-dose studies are generally part of the quality control test battery, repeated dose studies are pivotal. The animal model and treatment schedule selection and the parameters investigated are critical for the relevance of this safety assessment. Immunological and safety pharmacology parameters should be adapted to the specific properties of vaccines and added to this type of study. Vaccines intended for pregnant women or women of child-bearing age require embryo-fetal and post-natal studies with an adapted design to obtain appropriate fetal and maternal exposure during gestation with continuation into the post-natal period. Tests exist to detect hypersensitivity or autoimmune reactions, but require further validation. In addition to this tailor-made approach, any adjuvant or active component added to the vaccine formulation necessitate their own assessment using studies routinely performed for new drugs. From this review, vaccine toxicology would appear to be a separate discipline on its own whose predictivity will be increased by new method development.