Safety of vaccines used for routine immunization of U.S. children: a systematic review

Enhancing Vaccine Safety Capacity Globally: A Lifecycle Perspective

Major vaccine safety controversies have arisen in several countries beginning in the last decades of 20th century. Such periodic vaccine safety controversies are unlikely to go away in the near future as more national immunization programs mature with near elimination of target vaccine-preventable diseases that result in relative greater prominence of adverse events following immunizations, both true reactions and temporally coincidental events. There are several ways in which vaccine safety capacity can be improved to potentially mitigate the impact of future vaccine safety controversies. This paper aims to take a "lifecycle" approach, examining some potential pre- and post-licensure opportunities to improve vaccine safety, in both developed (specifically U.S. and Europe) and low- and middle-income countries.

Enhancing vaccine safety capacity globally: A lifecycle perspective

Major vaccine safety controversies have arisen in several countries beginning in the last decades of 20th century. Such periodic vaccine safety controversies are unlikely to go away in the near future as more national immunization programs mature with near elimination of target vaccine-preventable diseases that result in relative greater prominence of adverse events following immunizations, both true reactions and temporally coincidental events. There are several ways in which vaccine safety capacity can be improved to potentially mitigate the impact of future vaccine safety controversies. This paper aims to take a "lifecycle" approach, examining some potential pre- and post-licensure opportunities to improve vaccine safety, in both developed (specifically U.S. and Europe) and low- and middle-income countries.

Administration of thimerosal-containing vaccines to infant rhesus macaques does not result in autism-like behavior or neuropathology

Autism spectrum disorder (ASD) is a complex neurodevelopmental disorder. Some anecdotal reports suggest that ASD is related to exposure to ethyl mercury, in the form of the vaccine preservative, thimerosal, and/or receiving the measles, mumps, rubella (MMR) vaccine. Using infant rhesus macaques receiving thimerosal-containing vaccines (TCVs) following the recommended pediatric vaccine schedules from the 1990s and 2008, we examined behavior, and neuropathology in three brain regions found to exhibit neuropathology in postmortem ASD brains. No neuronal cellular or protein changes in the cerebellum, hippocampus, or amygdala were observed in animals following the 1990s or 2008 vaccine schedules. Analysis of social behavior in juvenile animals indicated that there were no significant differences in negative behaviors between animals in the control and experimental groups. These data indicate that administration of TCVs and/or the MMR vaccine to rhesus macaques does not result in neuropathological abnormalities, or aberrant behaviors, like those observed in ASD.

Effect of bivalent human papillomavirus vaccination on pregnancy outcomes: long term observational follow-up in the Costa Rica HPV Vaccine Trial

OBJECTIVE

To examine the effect of the bivalent human papillomavirus (HPV) vaccine on miscarriage.

DESIGN

Observational long term follow-up of a randomized, double blinded trial combined with an independent unvaccinated population based cohort.

SETTING

Single center study in Costa Rica.

PARTICIPANTS

7466 women in the trial and 2836 women in the unvaccinated cohort enrolled at the end of the randomized trial and in parallel with the observational trial component.

INTERVENTION

Women in the trial were assigned to receive three doses of bivalent HPV vaccine (n=3727) or the control hepatitis A vaccine (n=3739). Crossover bivalent HPV vaccination occurred in the hepatitis A vaccine arm at the end of the trial. Women in the unvaccinated cohort received (n=2836) no vaccination.

MAIN OUTCOME MEASURE

Risk of miscarriage, defined by the US Centers for Disease Control and Prevention as fetal loss within 20 weeks of gestation, in pregnancies exposed to bivalent HPV vaccination in less than 90 days and any time from vaccination compared with pregnancies exposed to hepatitis A vaccine and pregnancies in the unvaccinated cohort.

RESULTS

Of 3394 pregnancies conceived at any time since bivalent HPV vaccination, 381 pregnancies were conceived less than 90 days from vaccination. Unexposed pregnancies comprised 2507 pregnancies conceived after hepatitis A vaccination and 720 conceived in the unvaccinated cohort. Miscarriages occurred in 451 (13.3%) of all exposed pregnancies, in 50 (13.1%) of the pregnancies conceived less than 90 days from bivalent HPV vaccination, and in 414 (12.8%) of the unexposed pregnancies, of which 316 (12.6%) were in the hepatitis A vaccine group and 98 (13.6%) in the unvaccinated cohort. The relative risk of miscarriage for pregnancies conceived less than 90 days from vaccination compared with all unexposed pregnancies was 1.02 (95% confidence interval 0.78 to 1.34, one sided P=0.436) in unadjusted analyses. Results were similar after adjusting for age at vaccination (relative risk 1.15, one sided P=0.17), age at conception (1.03, P=0.422), and calendar year (1.06, P=0.358), and in stratified analyses. Among pregnancies conceived at any time from bivalent HPV vaccination, exposure was not associated with an increased risk of miscarriage overall or in subgroups, except for miscarriages at weeks 13-20 of gestation (relative risk 1.35, 95% confidence interval 1.02 to 1.77, one sided P=0.017).

CONCLUSIONS

There is no evidence that bivalent HPV vaccination affects the risk of miscarriage for pregnancies conceived less than 90 days from vaccination. The increased risk estimate for miscarriages in a subgroup of pregnancies conceived any time after vaccination may be an artifact of a thorough set of sensitivity analyses, but since a genuine association cannot totally be ruled out, this signal should nevertheless be explored further in existing and future studies.Trial registration Clinicaltrials.gov NCT00128661 and NCT01086709.

The re-emergency and persistence of vaccine preventable diseases

The introduction of vaccination worldwide dramatically reduced the incidence of pathogenic bacterial and viral diseases. Despite the highly successful vaccination strategies, the number of cases among vaccine preventable diseases has increased in the last decade and several of those diseases are still endemic in different countries. Here we discuss some epidemiological aspects and possible arguments that may explain why ancient diseases such as, measles, polio, pertussis, diphtheria and tuberculosis are still with us.

Parental Vaccine Hesitancy: Clinical Implications for Pediatric Providers

Despite being recognized as one of the greatest public health achievements, vaccines are increasingly under scrutiny for a multitude of reasons. "Parental vaccine hesitancy," an emerging term in today's literature, encompasses a wide range of concerns regarding vaccines and is believed to be responsible for decreasing coverage of many childhood vaccines. The threat to herd immunity posed by poor vaccine uptake increases the risk for resurgence of vaccine-preventable diseases. Pediatric primary health care providers have an obligation to respond to the increasing prevalence of vaccine hesitancy by providing education related to vaccines to ensure the safety and health of the population. The purpose of this article is to examine the most common concerns surrounding vaccine hesitancy and outline strategies for pediatric providers to address concerns with parents in the clinical setting.

Measles outbreaks: what does it represent for the elimination strategy in the region of the Americas? A call for the action

The US is experiencing a large multi-state measles outbreak that started in California in 2014. At this time, no source case for the outbreak has been identified. Measles was declared eliminated in the US in 2000, because at that time, there were high coverage rates with the two-dose schedule and these vaccines have been very immunogenic. Measles is still endemic in many parts of the world, and outbreaks can occur when unvaccinated groups are exposed to imported measles virus. The current multi-state outbreak underscores the ongoing risk of measles importation, the need for high measles vaccination coverage rates, and the importance of a prompt and appropriate public health response to individual cases and outbreaks. The US outbreak threatens measles control in the Americas. Strengthening immunization programs and keeping vaccination coverage rates above 95% with a two-dose schedule will be necessary for measles control strategies in the Americas.

Vaccine safety: medical contraindications, myths, and risk communication

On the basis of first principles, anaphylaxis to a vaccine or vaccine component is a contraindication to future receipt of that vaccine. • On the basis of strong evidence, live viral vaccines should not be administered to severely immunocompromised children. • On the basis of some evidence with consensus, children with egg allergies may receive inactivated influenza vaccine. • On the basis of strong evidence, neither measles-mumps-rubella vaccine nor thimerosal causes autism. • On the basis of some evidence with consensus, alternative vaccination schedules have no benefit and receipt of human papillomavirus vaccines does not result in promiscuity. • On the basis of first principles and consensus, vaccine risk communication requires a tailored approach to each individual family.

Polio vaccination: past, present and future

Live attenuated oral polio vaccine (OPV) and inactivated polio vaccine (IPV) are the tools being used to achieve eradication of wild polio virus. Because OPV can rarely cause paralysis and generate revertant polio strains, IPV will have to replace OPV after eradication of wild polio virus is certified to sustain eradication of all polioviruses. However, uncertainties remain related to IPV's ability to induce intestinal immunity in populations where fecal-oral transmission is predominant. Although substantial effectiveness and safety data exist on the use and delivery of OPV and IPV, several new research initiatives are currently underway to fill specific knowledge gaps to inform future vaccination policies that would assure polio is eradicated and eradication is maintained.

The history of the United States Advisory Committee on Immunization Practices (ACIP)

The United States Advisory Committee on Immunization Practices (ACIP) is a federal advisory committee that develops written recommendations for use of vaccines licensed by the Food and Drug Administration (FDA) for the U.S. civilian population. Vaccine development and disease outbreaks contributed to the need for a systematized, science-based, formal mechanism for establishing national immunization policy in this country. Formed in 1964, the ACIP was charged with this role. The committee has undergone significant changes in structure and operational activities during its 50-year history. The ACIP works closely with many liaison organizations to develop its immunization recommendations, which are harmonized among key professional medical societies. ACIP vaccine recommendations form two immunization schedules, which are updated annually: (1) the childhood and adolescent immunization schedule and (2) the adult immunization schedule. Today, once ACIP recommendations are adopted by the Director of the Centers for Disease Control and Prevention and the Secretary of the Department of Health and Human Services, these recommendations are published in Morbidity and Mortality Weekly Report (MMWR), become official policy, and are incorporated into the appropriate immunization schedule.