Does antigenic overload exist? The role of multiple immunizations in infants

Analysis of Parents' Attitudes and Knowledge toward Immunization and How These Factors Influence Their Decisions to Vaccinate Their Children against Human Papilloma Virus (HPV)

Background and objectives: Vaccination hesitancy is a growing problem associated with decreasing chances for the elimination of vaccine-preventable diseases through immunization. This research was conducted to learn about parents' attitudes toward vaccination, particularly against HPV, in the context of their beliefs and fears regarding immunization and the impact of these views on their children's vaccination decisions. An additional goal was to determine what views or convictions most often lead to the phenomenon of delaying or refusing vaccinations, especially HPV vaccines, in the surveyed community. Materials and Methods: An online questionnaire was conducted in which parents marked how they vaccinated their children with mandatory vaccinations and whether they took the opportunity to protect their children with additional vaccinations, including HPV and COVID-19. Respondents also marked the extent to which they agreed with the statements, regarding the safety of vaccinations, doubts about them, as well as popular anti-vaccine myths. Results: A total of 250 questionnaires were collected with data on the immunization of 425 children. Associations between specific beliefs and vaccine abstention were established. The most motivating factor for vaccination against HPV was the parent's awareness that the virus HP is the cause of cancer. The most inhibiting factor was respondent's compliance with the opinion that HPV vaccines can affect the child's sexual activity. Conclusions: The results indicate that information campaigns are needed, especially focusing on vaccine safety and the regularity and transparency of monitoring adverse effects. The obtained results will be used to create educational interventions against vaccination hesitancy more adapted to local conditions.

Using Typhoid Conjugate Vaccines to Prevent Disease, Promote Health Equity, and Counter Drug-Resistant Typhoid Fever

Typhoid fever is a serious disease that disproportionately impacts children in low-resource settings in sub-Saharan Africa, South and Southeast Asia, and the Western Pacific. The prevalence of antimicrobial-resistant strains of S. Typhi continue to increase worldwide. Two safe, effective, and cost-effective typhoid conjugate vaccines (TCVs) are World Health Organization-prequalified for the prevention of typhoid fever in children as young as 6 months. Typhoid conjugate vaccines have proven effectiveness in preventing drug-resistant S. Typhi and have been deployed successfully in outbreak response and routine immunization scenarios. Broad and equitable distribution of TCVs is essential to combat the spread and potentially devastating consequences of typhoid fever. It is vital to empower decision-makers in typhoid-endemic countries to introduce TCVs and for leaders to embrace this critical tool to prevent typhoid fever, slow the spread of drug-resistant S. Typhi strains, promote health equity, and save lives.

Determinants of effective vaccine coverage in low and middle-income countries: a systematic review and interpretive synthesis

BACKGROUND

Many children in low and middle-income countries remain unvaccinated, and vaccines do not always produce immunity. Extensive research has sought to understand why, but most studies have been limited in breadth and depth. This study documents existing evidence on determinants of vaccination and immunization and presents a conceptual framework of determinants.

METHODS

We used systematic review, content analysis, thematic analysis and interpretive synthesis to document and analyze the existing evidence on determinants of childhood vaccination and immunization.

RESULTS

We documented 1609 articles, including content analysis of 78 articles. Three major thematic models were described in the context of one another. Interpretive synthesis identified similarities and differences between studies, resulting in a conceptual framework with three principal vaccine utilization determinants: 1) Intent to Vaccinate, 2) Community Access and 3) Health Facility Readiness.

CONCLUSION

This study presents the most comprehensive systematic review of vaccine determinants to date. The conceptual framework represents a synthesis of multiple existing frameworks, is applicable in low and middle-income countries, and is quantitatively testable. Future researchers can use these results to develop competing conceptual frameworks, or to analyze data in a theoretically-grounded way. This review enables better research in the future, further understanding of immunization determinants, and greater progress against vaccine preventable diseases around the world.

Improved parental attitudes and beliefs through stepwise perinatal vaccination education

This study examined the effects of providing vaccination education during the perinatal period on Japanese parents' knowledge, attitudes, and beliefs about childhood vaccination. A cluster-randomized controlled-trial method was used on a sample of 160 pregnant women recruited from 9 obstetrical sites in Niigata, Japan. The treatment group received a stepwise interactive education intervention, while the control group received a general vaccination leaflet. Changes in parental attitudes toward and beliefs about infant vaccination were assessed on the child's one-month and 6-month birthdays using paper questionnaires. Of the initial 188 participants, 160 (90.4%) completed the final post-survey questionnaire. Scores on injunctive social norms (a morally neutral perception of the behavior of the majority) and descriptive social norms (a moral perception of what individuals should do) significantly increased in the treatment group (p = .02 and p = .01, respectively). There was a significant difference between the 2 groups over time in terms of perceived benefit (efficacy of available preventive actions) (p = .03), but no significant differences in perceived severity (seriousness of a disease outcome), perceived susceptibility (likelihood of getting a disease), perceived benefits, perceived behavioral control, or descriptive social norms between the groups at any time point or in the patterns of change over time (p > .31). Thus, stepwise perinatal vaccination education was found to positively influence maternal attitudes and beliefs about infant vaccination. This study suggests the importance of vaccination education during the perinatal period.

Immune overload: Parental attitudes toward combination and single antigen vaccines

Parental concerns have led to a recent decline in immunization coverage, resulting in outbreaks of diseases that were once under control in the US. As the CDC vaccination schedule continues to increase in complexity, the number of required injections per office visit increases as well. Some parents perceive that there is trauma associated with the administration of multiple injections, and research shows that having multiple vaccines due in a single visit is associated with delays and lower immunization rates. Combination vaccines make vaccination more efficient by incorporating the antigens of several different diseases into a single injection, but many parents worry that they may overload the child's developing immune system and leave him or her susceptible to secondary infections. This literature review synthesizes current evidence regarding the parental fear of vaccine-induced immune system overload and the fear of vaccine-associated trauma, in an attempt to understand the scope and nature of these fears. Despite the wealth of knowledge about each of these fears individually, it is still unknown which is of greater concern and how this affects parental decision-making.

How advances in immunology provide insight into improving vaccine efficacy

Vaccines represent one of the most compelling examples of how biomedical research has improved society by saving lives and dramatically reducing the burden of infectious disease. Despite the importance of vaccinology, we are still in the early stages of understanding how the best vaccines work and how we can achieve better protective efficacy through improved vaccine design. Most successful vaccines have been developed empirically, but recent advances in immunology are beginning to shed new light on the mechanisms of vaccine-mediated protection and development of long-term immunity. Although natural infection will often elicit lifelong immunity, almost all current vaccines require booster vaccination in order to achieve durable protective humoral immune responses, regardless of whether the vaccine is based on infection with replicating live-attenuated vaccine strains of the specific pathogen or whether they are derived from immunization with inactivated, non-replicating vaccines or subunit vaccines. The form of the vaccine antigen (e.g., soluble or particulate/aggregate) appears to play an important role in determining immunogenicity and the interactions between dendritic cells, B cells and T cells in the germinal center are likely to dictate the magnitude and duration of protective immunity. By learning how to optimize these interactions, we may be able to elicit more effective and long-lived immunity with fewer vaccinations.

[Risk of vaccination in children with epilepsy]

INTRODUCTION

The central nervous system, previously considered as "immune privileged", does exhibit features of inflammation in response to injury, infection or disease. We do not know its reactions on immunization. We do not know how common febrile seizures after vaccination are and if there are subgroups of children at higher risk. What is the long term outcome for children who had afebrile seizure after vaccination? Can the vaccine be a direct cause of a condition called an epileptic encephalopathy, where seizures damage the brain with the resulting epilepsy?

DISCUSSION AND CONCLUSION

It should not be forgotten that "benign infective childhood diseases" can, and do, kill, and that vaccines are a public health intervention saving many millions of lives around the world. Parents as well as doctors have fear: whether vaccinations can cause convulsions, epilepsy or encephalopathy. Large studies of this issue have produced conflicting results, although the recent consensus is that the risk of vaccine-induced epilepsy and or encephalopathy, if it exists at all, is extremely low. It is necessary to establish a proposed immunization program for children at neurologically high risk and for children with epilepsy to protect them and the whole population from infectious diseases, children from immunization adverse events, and avoid possibilities of legal trial. It is necessary to know everything about the risks and benefits of immunizations for each child. For each child, the risks of the disease, and its squeal, must be compared with the vaccine's protective efficacy and potential adverse reactions. Vaccination is given preference in nearly all children with epilepsy.

Fundamentals of clinical immunotoxicology

Whereas animal studies are invaluable for screening various chemical and drugs for immunotoxic potential, such systems are necessarily limited in their predictive value for humans given the differences in physiology, immune system structure and function, and various other parameters between humans and nonhuman animals. However, prospective experimental studies in humans are not always practical or ethical. What is needed is an approach for combining animal data, human data collected in the course of clinical studies, and modern tools of bioinformatics and systems biology. In this chapter, we will explore current assays and methodologies for assessing immunotoxic potential in humans using this multi--parameter approach.

The public perception of the value of vaccines - the case of Switzerland

Aim

In this original article, we seek to analyse the environment in which immunisation policies are adopted and, more specifically, the way the public perception of vaccines influences decision-making, by looking more closely at the case of Switzerland.

Subjects and methods

Historical and present-day examples of attitudes towards immunisation and specific vaccines, both on the part of the public and of health-care workers, are reviewed.

Results

Decision-making with regard to vaccine policy implementation has been and is still most often driven by fear: fear of disease (when perceived as rampant and/or dangerous), but also fear of vaccine-associated adverse events (when the disease is less or no longer “visible”). However, methodology for introducing evidence-based immunisation policies exists and can be used by public health authorities, while vaccination information systems (such as the Swiss InfoVac) have proven their usefulness in providing trustworthy, peer-based knowledge to health-care workers.

Conclusion

Only information based on clear, evidence-based data gathered and analysed according to solid methodological criteria coupled with adequate information of health-care workers (and thus patients) can ensure in future the implementation of scientifically coherent, publicly acceptable, and equitable immunisation policies.

Concurrent Vaccinations and U.S. Military Hospitalizations

PURPOSE

To investigate whether concurrent vaccinations (> or =2 vaccinations on consecutive days) are associated with hospitalization risk among U.S. military personnel.

METHODS

We analyzed Defense Medical Surveillance System data from January 1998 through December 2003 for 117,876 active component U.S. military personnel. We performed a time-to-event analysis of a historical cohort using a Cox proportional hazards model comparing hospitalizations during a 120-day postvaccination exposure interval to hospitalizations within a 120-day pre-exposure interval. We excluded personnel who were deployed during these intervals and those having hospitalizations 60 days prior to the concurrent vaccination exposure. Hazards ratios (HRs) with 95% confidence intervals were calculated, adjusting for demographic, occupational, health, and calendar variables.

RESULTS

We analyzed 19,743 persons having concurrent vaccinations. Receiving two or more vaccinations concurrently was not statistically associated with the adjusted risk of hospitalization (HR = 0.90 [0.75, 1.09]). Furthermore, no statistically significant associations were detected for 3 concurrent vaccinations (HR = 0.86 [0.58, 1.28]), 4 concurrent vaccinations (HR = 1.08, [0.66, 1.74]), or five or more concurrent vaccinations (HR = 0.86 [0.49, 1.51]).

CONCLUSIONS

No evidence was found that the concurrent receipt of multiple vaccinations is related to hospitalization risk among this sample of U.S. military personnel.

Delays in immunization have potentially serious health consequences

When children are not administered vaccinations according to the recommended schedule, they not only fail to receive timely protection from preventable diseases at a time when they are most vulnerable, but also increase their risk of never fully completing the vaccination course. Both outcomes compromise a successful childhood immunization program. Although current data suggest that vaccination rates are near 95% for school-aged children in the US, the rate of timely vaccination is much lower. A number of large studies have found that the majority of children are not currently vaccinated on schedule. Moreover, immunization levels for 2- to 3-year-old children have reached a plateau. It is essential to recognize that low overall rates of the targeted diseases mask the persistent threat they pose if adherence to vaccination schedules declines. A delay in one vaccine will produce a domino effect if catch-up adjustments in scheduled visits are not implemented aggressively. Published reports have demonstrated that failure to adhere to scheduled booster immunizations, not just the initial inoculation, results in resurgence of disease. Children fall off the vaccination schedule for a variety of reasons. Although many studies suggest that inadequate availability to healthcare is not a major determinant of delayed immunization, it still factors into parental decisions. Parents should be reminded of available healthcare options. From the clinician's end, computerization of healthcare records should allow for the generation of reminders. It is vital for clinicians to be aware that there are few contraindications to vaccination. They should also be prepared to address parental concerns regarding the safety of vaccines and should not hesitate to use topical analgesics or distraction techniques to facilitate inoculation. With the anticipation of several novel vaccines being added to the childhood and adolescent immunization schedule in the future, pediatricians face new challenges to not only provide every vaccination, but to do so in a timely manner. A lack of willingness on the part of the parent, or, occasionally, on the part of the clinician, to have multiple vaccines administered to the child during a single visit has been shown to be a significant cause of delayed vaccination. Since combination vaccines reduce the number of shots that need to be administered, the use of combination vaccines may provide the best opportunity to simplify the immunization schedule, increasing adherence in the process. Improved adherence to established schedules may present a major opportunity to further protect children from disease.

Adverse events following immunization: perception and evidence

PURPOSE OF REVIEW

The aim of this article is to highlight the evidence on new and ongoing vaccine safety concerns in the light of several vaccines recently licensed and others made available and recommended more widely.

RECENT FINDINGS

There is increasingly convincing epidemiologic and laboratory evidence against a causal relation of several alleged adverse events following immunization. The scientific framework to detect and investigate adverse events following immunization is increasingly robust.

SUMMARY

Currently available vaccines are safe in immunocompetent individuals and there is no evidence to deviate from current immunization schedules.

Should hepatitis B vaccine be used for infants?

Chronic hepatitis B virus infection causes nearly all the deaths from this virus. As the initial infection occurs without symptoms and decades prior to the onset of cirrhosis and liver cancer, these consequences are rarely recognized as being caused by the virus. Consequently, its public health importance is under-recognized. Safe and effective vaccines have now been available for over 20 years. Concerns have been raised regarding the mercury preservative in vaccines leading to potential toxicity. But the evidence to date does not support any association of hepatitis B vaccine with serious adverse consequences. Protecting infants through immunization is the most effective control strategy. By 2005, over 80% of countries had implemented routine infant immunization. In countries with relatively low rates of hepatitis B virus infection, some have argued to defer immunization until later life. However, these arguments focus on the more visible acute infection. The possible future cost from a single infant infection argues for universal infant hepatitis B immunization--given the very high costs of treating its consequences (e.g., liver transplant) and the very low price of the vaccine.

Factors underlying suboptimal childhood immunisation

This review considers possible reasons behind parents' missed vaccination opportunities in the context of the latest immunisation coverage rates for England. Suboptimal uptake is not exclusive to measles, mumps and rubella (MMR). A substantial proportion of children also miss diphtheria, tetanus and polio vaccination. For MMR and diphtheria, tetanus and polio, uptake of primary plus booster immunisation is lower than for the primary course alone. Several reasons for suboptimal uptake are identified from the international literature. These provide insights into parental decision-making and potential barriers to immunisation that may need to be addressed in efforts to improve coverage rates.

The safety of vaccines

Vaccines have had a considerable impact on society by eliminating the threat from several infectious diseases. Although vaccines have generally proven to be safe, safety issues have arisen that have resulted in some members of the public having a poor perception of vaccines. However, the technological advances made in recent years make the development of even safer vaccines a possibility. The new generation of vaccines will be based on pure recombinant proteins, conjugates and killed viruses. In addition, studies can be conducted in large numbers of individuals to allay unjustified fears of vaccine safety. These data will increase public confidence and ensure that vaccines become better appreciated as valuable products. Widespread confidence will be inspired by the effective communication of the realities of the benefit-to-risk ratios for each vaccine.