Safety monitoring in the Vaccine Adverse Event Reporting System (VAERS)

The Centers for Disease Control and Prevention (CDC) and the U.S. Food and Drug Administration (FDA) conduct post-licensure vaccine safety monitoring using the Vaccine Adverse Event Reporting System (VAERS), a spontaneous (or passive) reporting system. This means that after a vaccine is approved, CDC and FDA continue to monitor safety while it is distributed in the marketplace for use by collecting and analyzing spontaneous reports of adverse events that occur in persons following vaccination. Various methods and statistical techniques are used to analyze VAERS data, which CDC and FDA use to guide further safety evaluations and inform decisions around vaccine recommendations and regulatory action. VAERS data must be interpreted with caution due to the inherent limitations of passive surveillance. VAERS is primarily a safety signal detection and hypothesis generating system. Generally, VAERS data cannot be used to determine if a vaccine caused an adverse event. VAERS data interpreted alone or out of context can lead to erroneous conclusions about cause and effect as well as the risk of adverse events occurring following vaccination. CDC makes VAERS data available to the public and readily accessible online. We describe fundamental vaccine safety concepts, provide an overview of VAERS for healthcare professionals who provide vaccinations and might want to report or better understand a vaccine adverse event, and explain how CDC and FDA analyze VAERS data. We also describe strengths and limitations, and address common misconceptions about VAERS. Information in this review will be helpful for healthcare professionals counseling patients, parents, and others on vaccine safety and benefit-risk balance of vaccination.

Vaccines, adjuvants and autoimmunity

Vaccines and autoimmunity are linked fields. Vaccine efficacy is based on whether host immune response against an antigen can elicit a memory T-cell response over time. Although the described side effects thus far have been mostly transient and acute, vaccines are able to elicit the immune system towards an autoimmune reaction. The diagnosis of a definite autoimmune disease and the occurrence of fatal outcome post-vaccination have been less frequently reported. Since vaccines are given to previously healthy hosts, who may have never developed the disease had they not been immunized, adverse events should be carefully accessed and evaluated even if they represent a limited number of occurrences. In this review of the literature, there is evidence of vaccine-induced autoimmunity and adjuvant-induced autoimmunity in both experimental models as well as human patients. Adjuvants and infectious agents may exert their immune-enhancing effects through various functional activities, encompassed by the adjuvant effect. These mechanisms are shared by different conditions triggered by adjuvants leading to the autoimmune/inflammatory syndrome induced by adjuvants (ASIA syndrome). In conclusion, there are several case reports of autoimmune diseases following vaccines, however, due to the limited number of cases, the different classifications of symptoms and the long latency period of the diseases, every attempt for an epidemiological study has so far failed to deliver a connection. Despite this, efforts to unveil the connection between the triggering of the immune system by adjuvants and the development of autoimmune conditions should be undertaken. Vaccinomics is a field that may bring to light novel customized, personalized treatment approaches in the future.

Perinatal survival and health after maternal influenza A(H1N1)pdm09 vaccination: A cohort study of pregnancies stratified by trimester of vaccination

Large cohort studies demonstrated the safety of vaccination with the AS03 adjuvanted pandemic influenza vaccine, but data on first trimester vaccination safety are limited. We conducted a nationwide register-based retrospective cohort study in Finland, included singleton pregnancies present on 01 November 2009 and followed them from 01 November 2009 until delivery. Pregnancies with abortive outcome, pregnancies that started before 01 February 2009 and pregnancies of women, who received the AS03 adjuvanted pandemic influenza vaccine prior to the onset of pregnancy, were excluded. Our main outcome measures were hazard ratios comparing the risk of stillbirth, early neonatal death, moderately preterm birth, very preterm birth, moderately low birth weight, very low birth weight, and being small for gestational age between pregnancies exposed and unexposed to maternal influenza A(H1N1)pdm09 vaccination. The study population comprised 43,604 pregnancies; 34,241 (78.5%) women were vaccinated at some stage during pregnancy. The rates of stillbirth, early neonatal death, moderately preterm birth, and moderately low birth weight were similar between pregnant women exposed and unexposed to influenza A(H1N1)pdm09 vaccination. After adjusting for known risk factors, the relative rates were 0.90 (95% confidence interval 0.55-1.45) for very preterm birth, 0.84 (0.61-1.16) for very low birth weight, and 1.17 (0.98-1.40) for being small for gestational age. Also, in the subanalysis of 7839 women vaccinated during the first trimester, the rates did not indicate that maternal vaccination during the first trimester had any adverse impact on perinatal survival and health. The risk of adverse pregnancy outcomes was not associated with the exposure to the AS03 adjuvanted pandemic influenza vaccine. This study adds reassuring evidence on the safety of AS03 adjuvanted influenza vaccines when given in the first trimester and supports the recommendation of influenza vaccination to all pregnant women through all stages of pregnancy.

Deaths following vaccination: What does the evidence show?

Vaccines are rigorously tested and monitored and are among the safest medical products we use. Millions of vaccinations are given to children and adults in the United States each year. Serious adverse reactions are rare. However, because of the high volume of use, coincidental adverse events including deaths, that are temporally associated with vaccination, do occur. When death occurs shortly following vaccination, loved ones and others might naturally question whether it was related to vaccination. A large body of evidence supports the safety of vaccines, and multiple studies and scientific reviews have found no association between vaccination and deaths except in rare cases. During the US multi-state measles outbreak of 2014-2015, unsubstantiated claims of deaths caused by measles, mumps, and rubella (MMR) vaccine began circulating on the Internet, prompting responses by public health officials to address common misinterpretations and misuses of vaccine safety surveillance data, particularly around spontaneous reports submitted to the US Vaccine Adverse Event Reporting System (VAERS). We summarize epidemiologic data on deaths following vaccination, including examples where reasonable scientific evidence exists to support that vaccination caused or contributed to deaths. Rare cases where a known or plausible theoretical risk of death following vaccination exists include anaphylaxis, vaccine-strain systemic infection after administration of live vaccines to severely immunocompromised persons, intussusception after rotavirus vaccine, Guillain-Barré syndrome after inactivated influenza vaccine, fall-related injuries associated with syncope after vaccination, yellow fever vaccine-associated viscerotropic disease or associated neurologic disease, serious complications from smallpox vaccine including eczema vaccinatum, progressive vaccinia, postvaccinal encephalitis, myocarditis, and dilated cardiomyopathy, and vaccine-associated paralytic poliomyelitis from oral poliovirus vaccine. However, making general assumptions and drawing conclusions about vaccinations causing deaths based on spontaneous reports to VAERS - some of which might be anecdotal or second-hand - or from case reports in the media, is not a scientifically valid practice.

Vaccination errors reported to the Vaccine Adverse Event Reporting System, (VAERS) United States, 2000-2013

IMPORTANCE

Vaccination errors are preventable events. Errors can have impacts including inadequate immunological protection, possible injury, cost, inconvenience, and reduced confidence in the healthcare delivery system.

OBJECTIVES

To describe vaccination error reports submitted to the Vaccine Adverse Event Reporting System (VAERS) and identify opportunities for prevention.

METHODS

We conducted descriptive analyses using data from VAERS, the U.S. spontaneous surveillance system for adverse events following immunization. The VAERS database was searched from 2000 through 2013 for U.S. reports describing vaccination errors and reports were categorized into 11 error groups. We analyzed numbers and types of vaccination error reports, vaccines involved, reporting trends over time, and descriptions of errors for selected reports.

RESULTS

We identified 20,585 vaccination error reports documenting 21,843 errors. Annual reports increased from 10 in 2000 to 4324 in 2013. The most common error group was "Inappropriate Schedule" (5947; 27%); human papillomavirus (quadrivalent) (1516) and rotavirus (880) vaccines were most frequently involved. "Storage and Dispensing" errors (4983; 23%) included mostly expired vaccine administered (2746) and incorrect storage of vaccine (2202). "Wrong Vaccine Administered" errors (3372; 15%) included mix-ups between vaccines with similar antigens such as varicella/herpes zoster (shingles), DTaP/Tdap, and pneumococcal conjugate/polysaccharide. For error reports with an adverse health event (5204; 25% of total), 92% were classified as non-serious. We also identified 936 vaccination error clusters (i.e., same error, multiple patients, in a common setting) involving over 6141 patients. The most common error in clusters was incorrect storage of vaccine (582 clusters and more than 1715 patients).

CONCLUSIONS

Vaccination error reports to VAERS have increased substantially. Contributing factors might include changes in reporting practices, increasing complexity of the immunization schedule, availability of products with similar sounding names or acronyms, and increased attention to storage and temperature lapses. Prevention strategies should be considered.

Chorioamnionitis following vaccination in the Vaccine Adverse Event Reporting System

BACKGROUND

In October 2012, the Advisory Committee on Immunization Practices (ACIP) recommended a dose of tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) during each pregnancy, irrespective of the woman's prior history of receiving Tdap. A retrospective cohort study to assess the safety of Tdap vaccination in pregnant women in two Vaccine Safety Datalink (VSD) sites during 2010-2012 found a small but statistically significant increased risk of chorioamnionitis.

OBJECTIVE

We conducted a review of the VAERS database to describe reports of chorioamnionitis following receipt of any vaccines.

METHODS

We searched the VAERS database for reports of chorioamnionitis after any vaccine in the United States during the period from July 1, 1990 through February 2, 2014.

RESULTS

VAERS received 31 reports of chorioamnionitis out of 3389 pregnancy reports in 24 years. The three most common vaccines in these reports were 2009 H1N1 inactivated influenza, quadrivalent human papillomavirus (HPV4), and Tdap vaccines in 32%, 29% and 26% of reports, respectively. Fifty-eight percent of reports had at least one reported risk factor for chorioamnionitis. Chorioamnionitis was identified in 3 reports of spontaneous abortions and 6 stillbirths, 6 reports of preterm birth (two of whom died) and 16 reports of term birth; maternal outcomes included two reports of postpartum hemorrhage and one report of maternal admission to the intensive care unit. No maternal deaths were reported.

CONCLUSION

Chorioamnionitis was found to be uncommonly reported, representing 1% of pregnancy reports to VAERS. A majority of reports had at least one risk factor for chorioamnionitis.

The complementary roles of Phase 3 trials and post-licensure surveillance in the evaluation of new vaccines

Vaccines have led to significant reductions in morbidity and saved countless lives from many infectious diseases and are one of the most important public health successes of the modern era. Both vaccines' effectiveness and safety are keys for the success of immunisation programmes. The role of post-licensure surveillance has become increasingly recognised by regulatory authorities in the overall vaccine development process. Safety, purity, and effectiveness of vaccines are carefully assessed before licensure, but some safety and effectiveness aspects need continuing monitoring after licensure; Post-marketing activities are a necessary complement to pre-licensure activities for monitoring vaccine quality and to inform public health programmes. In the recent past, the availability of large databases together with data-mining and cross-linkage techniques have significantly improved the potentialities of post-licensure surveillance. The scope of this review is to present challenges and opportunities offered by vaccine post-licensure surveillance. While pre-licensure activities form the foundation for the development of effective and safe vaccines, post-licensure monitoring and assessment, are necessary to assure that vaccines are effective and safe when translated in real world settings. Strong partnerships and collaboration at an international level between different stakeholders is necessary for finding and optimally allocating resources and establishing robust post-licensure processes.

Relationship between Guillain-Barré syndrome, influenza-related hospitalizations, and influenza vaccine coverage

Some studies reported an increased risk of Guillain-Barré syndrome (GBS) within six weeks of influenza vaccination. It has also been suggested that this finding could have been confounded by influenza illnesses. We explored the complex relationship between influenza illness, influenza vaccination, and GBS, from an ecologic perspective using nationally representative data. We also studied seasonal patterns for GBS hospitalizations. Monthly hospitalization data (2000-2009) for GBS, and pneumonia and influenza (P&I) in the Nationwide Inpatient Sample were included. Seasonal influenza vaccination coverage for 2004-2005 through the 2008-2009 influenza seasons (August-May) was estimated from the National Health Interview Survey data. GBS seasonality was determined using Poisson regression. GBS and P&I temporal clusters were identified using scan statistics. The association between P&I and GBS hospitalizations in the same month (concurrent) or in the following month (lagged) were determined using negative binomial regression. Vaccine coverage increased over the years (from 19.7% during 2004-2005 to 35.5% during 2008-2009 season) but GBS hospitalization did not follow a similar pattern. Overall, a significant correlation between monthly P&I and GBS hospitalizations was observed (Spearman's correlation coefficient=0.7016, p<0.0001). A significant (p=0.001) cluster of P&I hospitalizations during December 2004-March 2005 overlapped a significant (p=0.001) cluster of GBS hospitalizations during January 2005-February 2005. After accounting for effects of monthly vaccine coverage and age, P&I hospitalization was significantly associated (p<0.0001) with GBS hospitalization in the concurrent month but not with GBS hospitalization in the following month. Monthly vaccine coverage was not associated with GBS hospitalization in adjusted models (both concurrent and lagged). GBS hospitalizations demonstrated a seasonal pattern with winter months having higher rates compared to the month of June. P&I hospitalization rates were significantly correlated with hospitalization rates for GBS. Vaccine coverage did not significantly affect the rates of GBS hospitalization at the population level.

Pediatric anaphylactic adverse events following immunization in Victoria, Australia from 2007 to 2013

BACKGROUND

Anaphylaxis is a rare life-threatening adverse event following immunization (AEFI). Variability in presentation can make differentiation between anaphylaxis and other AEFI difficult. This study summarizes pediatric anaphylaxis AEFI reported to an Australian state-based passive surveillance system.

METHODS

All suspected and reported pediatric (<18 years) anaphylaxis AEFI notified to SAEFVIC (Surveillance of Adverse Events Following Vaccination In the Community) Melbourne, Australia, between May 2007 to May 2013 were analyzed. Clinical descriptions of the AEFI, using the internationally recognized Brighton Collaboration case definition (BCCD) and final outcome were documented.

RESULTS

93% (25/27) of AEFI classified as anaphylaxis met BCCD criteria, with 36% (9/25), assessed as the highest level of diagnostic certainty (Level 1). Median age was 4.7 years (range 0.3-16.2); 48% of cases were male. The vaccine antigens administered included: diphtheria, tetanus, acellular pertussis (DTaP) alone or in combination vaccines containing other antigens in 11 of 25 cases (44%); and live attenuated measles mumps rubella (MMR) vaccine for six (five also had other vaccines concomitantly administered). The estimated incidence rate of anaphylaxis for DTaP vaccines was 0.36 cases per 100,000 doses, and 1.25 per 100,000 doses for MMR vaccines. The majority of cases had rapid onset, but in 24% (6/25) of cases, first symptoms of anaphylaxis developed ≥30 min after immunization. In 60% (15/25) of cases, symptoms resolved ≤60 min of presentation. Intramuscular adrenaline was administered in 90% (18/25) of cases. All cases made a full recovery with no sequelae identified.

CONCLUSION

This comprehensive case series of pediatric anaphylaxis as an AEFI identified that diagnostic criteria are useful when applied to a passive vaccine surveillance system when adequate clinical information is available. Anaphylaxis as an AEFI is rare and usually begins within 30 min of vaccination. However, healthcare professionals and vaccinees/parents should be aware that onset of anaphylaxis can be delayed beyond 30 min following immunization and that medical attention should be sought promptly if anaphylaxis is suspected.

Post-licensure surveillance of quadrivalent live attenuated influenza vaccine United States, Vaccine Adverse Event Reporting System (VAERS), July 2013-June 2014

BACKGROUND

Quadrivalent live attenuated influenza vaccine (LAIV4) was approved in 2012 for healthy persons aged 2-49 years. Beginning with the 2013-2014 influenza season, LAIV4 replaced trivalent live attenuated influenza vaccine (LAIV3).

METHODS

We analyzed LAIV4 reports to VAERS, a national spontaneous reporting system. LAIV4 reports in 2013-2014 were compared to LAIV3 reports from the previous three influenza seasons. Medical records were reviewed for non-manufacturer serious reports (i.e., death, hospitalization, prolonged hospitalization, life-threatening illness, permanent disability) and reports of selected conditions of interest. We conducted Empirical Bayesian data mining to identify disproportional reporting for LAIV4.

RESULTS

In 2013-2014, 12.7 million doses of LAIV4 were distributed and VAERS received 779 reports in individuals aged 2-49 years; 95% were non-serious. Expired drug administered (42%), fever (13%) and cough (8%) were most commonly reported in children aged 2-17 years when LAIV4 was administered alone, while headache (18%), expired drug administered (15%) and exposure during pregnancy (12%) were most common in adults aged 18-49 years. We identified one death report in a child who died from complications of cerebellar vascular tumors. Among non-death serious reports, neurologic conditions were common in children and adults. In children, seizures (3) and Guillain-Barré syndrome (2) were the most common serious neurologic outcomes. We identified three serious reports of asthma/wheezing following LAIV4 in children. Data mining detected disproportional reporting for vaccine administration errors and for influenza illness in children.

CONCLUSIONS

Our analysis of VAERS reports for LAIV4 did not identify any concerning patterns. The data mining finding for reports of influenza illness is consistent with low LAIV4 vaccine effectiveness observed for influenza A disease in children in 2013-2014. Reports of LAIV4 administration to persons in whom the vaccine is not recommended (e.g., pregnant women) indicate the need for education, training and screening regarding indications.

Influenza vaccination during pregnancy and its usefulness to mothers and their young infants

The current approach to protecting pregnant women from influenza infection and serious influenza-related complications is vaccination. It is, therefore, critical to evaluate the vaccine's safety, immunogenicity, and protection efficacy during pregnancy. However, because it is affected by previous influenza vaccination or infection, the efficacy of the seasonal trivalent inactivated influenza vaccine is difficult to evaluate in pregnant women. The A/H1N1pdm pandemic in 2009 provided us with the opportunity to evaluate the immunogenicity of the influenza vaccine unaffected by previous vaccinations or infections. Vaccination with inactivated influenza virus during pregnancy elicited neutralizing antibody titers that were sufficient and comparable to those of naturally infected individuals. Furthermore, post-pandemic surveys provided a wealth of definitive information on vaccine efficacy and safety. In addition, transplacental transfer of antibodies following vaccination protected newborn infants against influenza infection. With reports showing the effectiveness of influenza vaccine during pregnancy, it is suggested that influenza vaccination benefits both mothers and their young infants.

Live virus vaccines based on a yellow fever vaccine backbone: standardized template with key considerations for a risk/benefit assessment

The Brighton Collaboration Viral Vector Vaccines Safety Working Group (V3SWG) was formed to evaluate the safety of live, recombinant viral vaccines incorporating genes from heterologous viruses inserted into the backbone of another virus (so-called "chimeric virus vaccines"). Many viral vector vaccines are in advanced clinical trials. The first such vaccine to be approved for marketing (to date in Australia, Thailand, Malaysia, and the Philippines) is a vaccine against the flavivirus, Japanese encephalitis (JE), which employs a licensed vaccine (yellow fever 17D) as a vector. In this vaccine, two envelope proteins (prM-E) of YF 17D virus were exchanged for the corresponding genes of JE virus, with additional attenuating mutations incorporated into the JE gene inserts. Similar vaccines have been constructed by inserting prM-E genes of dengue and West Nile into YF 17D virus and are in late stage clinical studies. The dengue vaccine is, however, more complex in that it requires a mixture of four live vectors each expressing one of the four dengue serotypes. This vaccine has been evaluated in multiple clinical trials. No significant safety concerns have been found. The Phase 3 trials met their endpoints in terms of overall reduction of confirmed dengue fever, and, most importantly a significant reduction in severe dengue and hospitalization due to dengue. However, based on results that have been published so far, efficacy in preventing serotype 2 infection is less than that for the other three serotypes. In the development of these chimeric vaccines, an important series of comparative studies of safety and efficacy were made using the parental YF 17D vaccine virus as a benchmark. In this paper, we use a standardized template describing the key characteristics of the novel flavivirus vaccine vectors, in comparison to the parental YF 17D vaccine. The template facilitates scientific discourse among key stakeholders by increasing the transparency and comparability of information. The Brighton Collaboration V3SWG template may also be useful as a guide to the evaluation of other recombinant viral vector vaccines.

Safety of quadrivalent human papillomavirus vaccine (Gardasil) in pregnancy: adverse events among non-manufacturer reports in the Vaccine Adverse Event Reporting System, 2006-2013

BACKGROUND

In 2006, quadrivalent human papillomavirus (HPV4; Gardasil, Merck & Co., Inc.) vaccine was licensed in the US for use in females aged 9-26 years. HPV4 is not recommended during pregnancy; however, inadvertent administration during pregnancy may occur.

OBJECTIVES

To evaluate and summarize reports to the Vaccine Adverse Event Reporting System (VAERS) in pregnant women who received HPV4 vaccine and assess for potentially concerning adverse events among non-manufacturer reports.

METHODS

We searched the VAERS database for non-manufacturer reports of adverse events (AEs) in pregnant women who received HPV4 vaccine from 6/1/2006 to 12/31/2013. We conducted clinical review of reports and available medical records.

RESULTS

We found 147 reports after HPV4 vaccine administered to pregnant women. The most frequent pregnancy-specific AE was spontaneous abortion in 15 (10.2%) reports, followed by elective terminations in 6 (4.1%). Maternal fever was the most frequent non-pregnancy-specific AE in 3 reports. Two reports of major birth defects were received. No maternal deaths were noted. One hundred-three (70.1%) reports did not describe an AE.

CONCLUSIONS

This review of VAERS non-manufacturer reports following vaccination with HPV4 in pregnancy did not find any unexpected patterns in maternal or fetal outcomes.

Febrile seizures following measles and varicella vaccines in young children in Australia

BACKGROUND

Febrile seizures (FS) are common in childhood with incidence peaking in the second year of life when measles and varicella-containing vaccines are administered. This study aimed to examine the vaccine-attributable risk of FS following separate administration of MMR and monovalent varicella vaccines (VV) prior to a planned change to MMRV as the second dose of measles-containing vaccine at 18 months of age.

METHODS

All FS cases in children aged <5 years from 1st January 2012 to 30th April 2013 were identified from emergency department (ED) and inpatient databases at five Australian tertiary paediatric hospitals participating in PAEDS (Paediatric Active Enhanced Disease Surveillance). Immunization records were obtained from the Australian Childhood Immunization Register (ACIR). The relative incidence (RI) of FS following MMR dose 1 (MMR1) and VV in children aged 11-23 months was determined using the self-controlled case series (SCCS) method and used to calculate attributable risk.

RESULTS

There were 2013 FS episodes in 1761 children. The peak age at FS was 18 months. The risk of FS was significantly increased 5-12 days post receipt of MMR1 at 12 months (RI=1.9 [95% CI: 1.3-2.9]), but not after VV at 18 months (RI=0.6 [95% CI: 0.3-1.2]. The estimated excess annual number of FS post MMR1 was 24 per 100,000 vaccinated children aged 11-23 months (95% CI=7-49 cases per 100,000) or 1 per 4167 doses.

CONCLUSIONS

Our study detected the expected increased FS risk post MMR1 vaccine at 12 months, but monovalent varicella vaccine at age 18 months was not associated with increased risk of FS. This provides baseline data to assess the risk of FS post MMRV, introduced in Australia as the second dose of measles-containing vaccine at 18 months of age in July 2013.

Events supposedly attributable to vaccination or immunization during pandemic influenza A (H1N1) vaccination campaigns in Latin America and the Caribbean

As part of the vaccination activities against influenza A[H1N1]pdm vaccine in 2009-2010, countries in Latin American and the Caribbean (LAC) implemented surveillance of events supposedly attributable to vaccines and immunization (ESAVI). We describe the serious ESAVI reported in LAC in order to further document the safety profile of this vaccine and highlight lessons learned. We reviewed data from serious H1N1 ESAVI cases from LAC countries reported to the Pan American Health Organization/World Health Organization. We estimated serious ESAVI rates by age and target group, as well as by clinical diagnosis, and completed descriptive analyses of final outcomes and classifications given in country. A total of 1000 serious ESAVI were reported by 18 of the 29 LAC countries that vaccinated against A[H1N1]pdm. The overall reporting rate in LAC was 6.91 serious ESAVI per million doses, with country reporting rates ranging from 0.77 to 64.68 per million doses. Rates were higher among pregnant women (16.25 per million doses) when compared to health care workers (13.54 per million doses) and individuals with chronic disease (4.03 per million doses). The top three most frequent diagnoses were febrile seizures (12.0%), Guillain-Barré Syndrome (10.5%) and acute pneumonia (8.0%). Almost half (49.1%) of the serious ESAVI were reported among children aged <18 years of age; within this group, the highest proportion of cases was reported among those aged <2 years (53.1%). Of all serious ESAVI reported, 37.8% were classified as coincidental, 35.3% as related to vaccine components, 26.4% as non-conclusive and 0.5% as a programmatic error. This regional overview of A[H1N1]pdm vaccine safety data in LAC estimated the rate of serious ESAVI at lower levels than other studies. However, the ESAVI diagnosis distribution is comparable to the published literature. Lessons learned can be applied in the response to future pandemics.

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.

Use of placebos in Phase 1 preventive HIV vaccine clinical trials

Phase 1 preventive HIV vaccine trials are often designed as randomized, double-blind studies with the inclusion of placebo recipients. Careful consideration is needed to determine when the inclusion of placebo recipients is highly advantageous and when it is optional for achieving the study objectives of assessing vaccine safety, tolerability and immunogenicity. The inclusion of placebo recipients is generally important to form a reference group that ensures fair evaluation and interpretation of subjective study endpoints, or endpoints whose levels may change due to exposures besides vaccination. In some settings, however, placebo recipients are less important because other data sources and tools are available to achieve the study objectives.

Safety of immunization during pregnancy: a review of the evidence of selected inactivated and live attenuated vaccines

Vaccine-preventable infectious diseases are responsible for significant maternal, neonatal, and young infant morbidity and mortality. While there is emerging scientific evidence, as well as theoretical considerations, indicating that certain vaccines are safe for pregnant women and fetuses, policy formulation is challenging because of perceived potential risks to the fetus. This report presents an overview of available evidence on pregnant women vaccination safety monitoring in pregnant women, from both published literature and ongoing surveillance programs. Safety data were reviewed for vaccines against diseases which increase morbidity in pregnant women, their fetus or infant as well as vaccines which are used in mass vaccination campaigns against diseases. They include inactivated seasonal and pandemic influenza, mono- and combined meningococcal polysaccharide and conjugated vaccines, tetanus toxoid and acellular pertussis combination vaccines, as well as monovalent or combined rubella, oral poliomyelitis virus and yellow fever vaccines. No evidence of adverse pregnancy outcomes has been identified from immunization of pregnant women with these vaccines.

Safety of inactivated monovalent pandemic (H1N1) 2009 vaccination during pregnancy: a population-based study in Taiwan

BACKGROUND

Pregnant women were prioritized for H1N1 vaccination during the 2009-2010 pandemic. Safety concerns exist with vaccinating pregnant women, particularly in their first trimesters.

METHODS

We linked computerized data on H1N1 vaccination, National Health Insurance, and Taiwan Birth Registry and identified events of spontaneous abortions (SABs) and all singleton births that occurred/delivered during November 1, 2009-September 30, 2010. The observation period for each case of SAB (6-19 weeks gestation) was divided into period at risk (1-28 days after vaccination) and control periods (the remaining person-days until SAB). The self-controlled case series method for truncated observational periods assessed the incidence rate ratio (IRR) of SAB during the 1-28 days compared with those in the control period. The case-control design matched each case of adverse fetal outcomes to up to 10 controls on fetal sex and year/month of pregnancy onset, and calculated matched odds ratio (OR) on H1N1 vaccination at <14 or ≥14 weeks gestation.

RESULTS

Sixty-five women with SAB had received H1N1 vaccination at 6-19 weeks gestation. The IRR of SAB for the risk period 1-28 days was 1.03 (95% confidence interval [CI] 0.55-1.93). Among the 147,294 live births and 1354 stillbirths, maternal H1N1 vaccine receipt at <14 weeks gestation was associated with significantly reduced likelihood of small for gestational age (SGA) birth (OR 0.72, 95% CI 0.61-0.84) and birth defect (OR 0.46, 95% CI 0.22-1.00), whereas receipt at ≥14 weeks gestation was associated with significantly reduced likelihood of stillbirth (OR 0.63, 95% CI 0.46-0.86), prematurity (OR 0.90, 95% CI 0.83-0.97), low birth weight (OR 0.81, 95% CI 0.74-0.88), and SGA birth (OR 0.90, 95% CI 0.84-0.97).

CONCLUSIONS

H1N1 vaccination during pregnancy did not increase risk of SAB or adverse fetal outcomes.

Post-licensure surveillance of trivalent live attenuated influenza vaccine in adults, United States, Vaccine Adverse Event Reporting System (VAERS), July 2005-June 2013

BACKGROUND

Trivalent live attenuated influenza vaccine (LAIV3) was licensed and recommended for use in 2003 in children and adults 2-49 years of age. Post-licensure safety data have been limited, particularly in adults.

METHODS

We searched Vaccine Adverse Event Reporting System (VAERS) for US reports after LAIV3 from July 1, 2005-June 30, 2013 (eight influenza seasons) in adults aged ≥ 18 years old. We conducted descriptive analyses and clinically reviewed serious reports (i.e., death, life-threatening illness, hospitalization, prolonged hospitalization, or permanent disability) and reports of selected conditions of interest. We used empirical Bayesian data mining to identify adverse events (AEs) that were reported more frequently than expected. We calculated crude AE reporting rates to VAERS by influenza season.

RESULTS

During the study period, VAERS received 1207 LAIV3 reports in adults aged 18-49 years old; 107 (8.9%) were serious, including four death reports. The most commonly reported events were expired drug administered (n=207, 17%), headache (n=192, 16%), and fever (n=133, 11%). The most common diagnostic categories for non-fatal serious reports were neurological (n=40, 39%), cardiovascular (n=14, 14%), and other non-infectious conditions (n=20, 19%). We noted a higher proportion of Guillain-Barré syndrome (GBS) and cardiovascular reports in the Department of Defense (DoD) population compared to the civilian population. Data mining detected disproportional reporting of ataxia (n=15); clinical review revealed that ataxia was a component of diverse clinical entities including GBS.

CONCLUSIONS

Review of VAERS reports are reassuring, the only unexpected safety concern for LAIV3 identified was a higher than expected number of GBS reports in the DoD population, which is being investigated. Reports of administration of expired LAIV3 represent administration errors and indicate the need for education, training and screening regarding the approved indications.

Safety of a nasal vaccine against Streptococcus pneumoniae using heat-killed Lactobacillus casei as adjuvant

Streptococcus pneumoniae is a highly important respiratory pathogen that causes infections in children, elderly people and immunocompromised people around the world. Pneumococcal vaccines licensed did not reach to eradicate the pneumococcal infection. In a previous study was demonstrated the effectiveness of a nasal experimental vaccine that consisted in a pneumococcal protective protein A (PppA) co-administrated with heat-killed-Lactobacillus casei (LcM), in mice model of respiratory pneumococcal challenge. In the present work the safety of the experimental vaccine LcM+PppA and its components were evaluated through hematological, biochemical and immune parameters in a model infection with S. pneumoniae. Thus, alanine transaminase activity, creatinine levels, lactate dehydrogenase activity, C reactive protein levels, corticosterone levels in serum, total and differential leukocyte counts in blood and bronchoalveolar lavages (BAL) and IgE in BAL, were evaluated. Experimental vaccine: LcM+PppA nasally administered does not induce harmful effects in our vaccination-infection model. Studied parameters showed LcM+PppA's safety in liver, kidney, pulmonary and systemic levels. Although studies in experimental animals do not guarantee security for the application of the vaccine on humans, they are important evidence for the planning and subsequent clinical trials in humans.

The Vaccine Safety Datalink: successes and challenges monitoring vaccine safety

The Vaccine Safety Datalink (VSD) is a collaborative project between the Centers for Disease Control and Prevention (CDC) and 9 health care organizations. Established in 1990, VSD is a vital resource informing policy makers and the public about the safety of vaccines used in the United States. Large linked databases are used to identify and evaluate adverse events in over 9 million individuals annually. VSD generates rapid, important safety assessments for both routine vaccinations and emergency vaccination campaigns. VSD monitors safety of seasonal influenza vaccines in near-real time, and provided essential information on the safety of influenza A (H1N1) 2009 monovalent vaccine during the recent pandemic. VSD investigators have published important studies demonstrating that childhood vaccines are not associated with autism or other developmental disabilities. VSD prioritizes evaluation of new vaccines; searches for possible unusual health events after vaccination; monitors vaccine safety in pregnant women; and has pioneered development of biostatistical research methods.

pediatric residency programs

OBJECTIVE

To determine if U.S. pediatric residency programs provide formal training in vaccine safety to address parental vaccine concerns.

METHODS

An electronic survey was mailed to all members of the Association of Pediatric Program Directors (APPD) to assess (1) if U.S. pediatric residency programs were providing formal vaccine safety training, (2) the content and format of the training if provided, and (3) interest in a training module for programs without training. Two follow-up surveys were mailed at 2 week intervals. Responses to the survey were collected at 4 weeks following the last mailing and analyzed. Logistic regression was used to assess the impact of program size on the likelihood of vaccine safety training. Pearson's chi square was used to compare programs with and without formal vaccine safety training in 5 U.S. regions.

RESULTS

The survey was sent to 199 APPD members; 92 completed the survey (response rate 46.2%). Thirty-eight respondents (41%) had formal training in vaccine safety for pediatric residents at their programs; 54 (59%) did not. Of those that did not, the majority (81.5%) were interested in formal vaccine safety training for their residents. Of all respondents, 78% agreed that training in vaccine safety was a high priority for resident education. Thirty-five percent of all respondents agreed that local parental attitudes about vaccines influenced the likelihood of formal vaccine safety training.

CONCLUSION

Most pediatric residency programs surveyed do not include formal training on vaccine safety; yet, such training is supported by pediatric residency program directors as a priority for pediatric residents.

Safety of diphtheria, tetanus, acellular pertussis and inactivated poliovirus (DTaP-IPV) vaccine

BACKGROUND

In 2008, a diphtheria, tetanus, acellular pertussis, and inactivated poliovirus combined vaccine (DTaP-IPV) was licensed for use in children 4 through 6 years of age. While pre-licensure studies did not demonstrate significant safety concerns, the number vaccinated in these studies was not sufficient to examine the risk of uncommon but serious adverse events.

OBJECTIVE

To assess the risk of serious adverse events following DTaP-IPV vaccination.

METHODS

The study was conducted from January 2009 through September 2012 in the Vaccine Safety Datalink (VSD) project. In the VSD, electronic vaccination and encounter data are updated and aggregated weekly as part of ongoing surveillance activities. Based on previous reports and biologic plausibility, eight potential adverse events were monitored: meningitis/encephalitis; seizures; stroke; Guillain-Barré syndrome; Stevens-Johnson syndrome; anaphylaxis; serious allergic reactions other than anaphylaxis; and serious local reactions. Adverse event rates in DTaP-IPV recipients were compared to historical incidence rates in the VSD population prior to 2009. Sequential probability ratio testing was used to analyze the data on a weekly basis.

RESULTS

During the study period, 201,116 children received DTaP-IPV vaccine. Ninety-seven percent of DTaP-IPV recipients also received other vaccines on the same day, typically measles-mumps-rubella and varicella vaccines. There was no statistically significant increased risk of any of the eight pre-specified adverse events among DTaP-IPV recipients when compared to historical incidence rates.

CONCLUSIONS

In this safety surveillance study of more than 200,000 DTaP-IPV vaccine recipients, there was no evidence of increased risk for any of the pre-specified adverse events monitored. Continued surveillance of DTaP-IPV vaccine safety may be warranted to monitor for rare adverse events, such as Guillain-Barré syndrome.

Evaluation of the feasibility of a state-based vaccine safety advice network

The vaccine safety advice network is a collaborative pilot project between Vanderbilt University Medical Center, the Tennessee Department of Health, and the Centers for Disease Control and Prevention to assess the feasibility of addressing vaccine safety questions posed by healthcare providers in near real-time. Using a two-tier response system and an electronic database for query submission, the pilot project received ten queries in three and one half months. Two of three pre-specified benchmarks for program evaluation, addressing queries within 24 h of receipt and 100% provider satisfaction, were met; one benchmark, the percentage of questions addressed by Tier 1 staff, was not met. Limitations included few submitted queries primarily involving children in the pilot period, "after-only" program evaluation, and limited geographic generalizability. The study demonstrates a successful partnership between federal, state and academic institutions and a feasible method to respond to healthcare provider inquiries about vaccine safety in near real-time.

Adverse events following immunization in Ontario's female school-based HPV program

BACKGROUND

In September 2007, a school-based human papillomavirus (HPV) vaccination program targeting grade 8 girls (approximately 13 years old) and delivered by public health was implemented in Ontario, Canada. We assessed reports of adverse events following immunization (AEFI) from the school-based program as part of quadrivalent HPV (HPV4) vaccine safety surveillance and to contribute to a comprehensive HPV vaccine program evaluation.

METHODS

AEFIs following HPV4 vaccine (Gardasil(®)) administered between September 1, 2007 and December 31, 2011 were extracted from the province's reportable disease system. Confirmed AEFI reports among females 12-15 years old (i.e. assumed to have received vaccine through the program) were included. Events were grouped according to provincial AEFI case definitions. Rates were calculated using doses distributed as the denominator.

RESULTS

Between 2007 and 2011, 133 confirmed AEFIs were reported while 691,994 HPV4 vaccine doses were distributed in the school-based program. The overall reporting rate was 19.2 HPV4 AEFI per 100,000 doses distributed. Annual reporting rates decreased from 30.0 to 18.3 per 100,000 doses distributed. Frequently reported events included 'allergic reaction-dermatologic/mucosa' (25%), 'rash' (22%), and 'local/injection site reaction' (20%); 26% of reports had a non-specific event of 'other severe/unusual events' selected. Ten serious AEFIs were reported (7.5% of reports) including 2 anaphylaxis, 2 seizures, 1 thrombocytopenia and 1 death. Further review found that the reports of anaphylaxis did not meet the Brighton anaphylaxis definition and the death was attributed to a preexisting cardiac condition.

CONCLUSIONS

Overall these findings are consistent with the safety profile of HPV4 vaccine from pre-licensure clinical trials and post-marketing surveillance reports and importantly, no new safety signals were identified, especially no reports of VTE in this younger female population. Continued assessment of HPV4 AEFI surveillance data may be important to detect and investigate safety signals.

Identification of seizures among adults and children following influenza vaccination using health insurance claims data

INTRODUCTION

Post-licensure surveillance of adverse events following vaccination or prescription drug use often relies on electronic healthcare data to efficiently detect and evaluate safety signals. The accuracy of seizure-related diagnosis codes in identifying true incident seizure events in vaccine safety studies is influenced by factors such as clinical setting of diagnosis and age. To date, most studies of post-vaccination seizure have focused on pediatric populations. More information is needed on how well seizure can be identified in adults and children using algorithms that rely on electronic healthcare data.

METHODS

This validation study was part of a larger safety study of influenza vaccination during the 2009-2010 and 2010-2011 influenza seasons. Children and adults receiving influenza vaccination were drawn from an administrative claims database of a large United States healthcare insurer. Potential seizure events were identified using an algorithm of ICD-9 diagnosis codes associated with an emergency department (ED) visit or hospitalization within pre-specified risk windows following influenza vaccination. Seizure events were confirmed through medical record review. The positive predictive value (PPV) of the algorithm was calculated within each diagnostic setting and stratified by age group, ICD-9 code group, and sex.

RESULTS

Review confirmed 113 out of 176 potential seizure events. The PPVs were higher in the ED setting (93.9%) than in the inpatient setting (38.3%). The PPVs by age varied within the ED setting (98.2% in <7 years, 76.9% in 7-24 years, 92.3% in ≥25 years) and within the inpatient setting (64.7% in <7 years, 33.3% in 7-24 years, 32.3% in ≥25 years).

CONCLUSIONS

Our algorithm for identification of seizure events using claims data had a high level of accuracy in the emergency department setting in young children and older adults and a lower, but acceptable, level of accuracy in older children and young adults.

Evaluating the safety of influenza vaccine using a claims-based health system

INTRODUCTION

As part of the Centers for Disease Control and Prevention's monitoring and evaluation activities for influenza vaccines, we examined relationships between influenza vaccination and selected outcomes in the 2009-2010 and 2010-2011 influenza seasons in a claims-based data environment.

METHODS

We included patients with claims for trivalent influenza vaccine (TIV) and/or 2009 pandemic influenza A H1N1 vaccine (H1N1) during the 2009-2010 and 2010-2011 influenza seasons. Patients were followed for several pre-specified outcomes identified in claims. Seizures and Guillain-Barré Syndrome were selected a priori for medical record confirmation. We estimated incidence rate ratios (IRR) using a self-controlled risk interval (SCRI) or a historical comparison design. Outcomes with elevated IRRs, not selected a priori for medical record review, were further investigated with review of claims histories surrounding the outcome date to determine whether the potential event could be ruled-out or attributed to other causes based on the pattern of medical care.

RESULTS

In the 2009-2010 season, no significant increased risks for outcomes following H1N1 vaccination were observed. Following TIV administration, the IRR for peripheral nervous system disorders and neuropathy was slightly elevated (1.07, 95% CI: 1.01-1.13). The IRR for anaphylaxis following TIV was 28.55 (95% CI: 3.57-228.44). After further investigation of claims histories, the majority of potential anaphylaxis cases had additional claims around the time of the event indicating alternate explanatory factors or diagnoses. In the 2010-2011 season following TIV administration, a non-significant elevated IRR for anaphylaxis was observed with no other significant outcome findings.

CONCLUSION

After claims history review, we ultimately found no increased outcome risk following administration of 998,881 TIV and 538,257 H1N1 vaccine doses in the 2009-2010 season, and 1,158,932 TIV doses in the 2010-2011 season.

Predictive markers of safety and immunogenicity of adjuvanted vaccines

Vaccination represents one of the greatest public health triumphs; in part due to the effect of adjuvants that have been included in vaccine preparations to boost the immune responses through different mechanisms. Although a variety of novel adjuvants have been under development, only a limited number have been approved by regulatory authorities for human vaccines. This report reflects the conclusions of a group of scientists from academia, regulatory agencies and industry who attended a conference on the current state of the art in the adjuvant field. Held at the U.S. Pharmacopeial Convention (USP) in Rockville, Maryland, USA, from 18 to 19 April 2013 and organized by the International Association for Biologicals (IABS), the conference focused particularly on the future development of effective adjuvants and adjuvanted vaccines and on overcoming major hurdles, such as safety and immunogenicity assessment, as well as regulatory scrutiny. More information on the conference output can be found on the IABS website, http://www.iabs.org/.

Adverse events after Fluzone ® Intradermal vaccine reported to the Vaccine Adverse Event Reporting System (VAERS), 2011-2013

BACKGROUND

In May 2011, the first trivalent inactivated influenza vaccine exclusively for intradermal administration (TIV-ID) was licensed in the US for adults aged 18-64 years.

OBJECTIVE

To characterize adverse events (AEs) after TIV-ID reported to the US Vaccine Adverse Event Reporting System (VAERS), a spontaneous reporting surveillance system.

METHODS

We searched VAERS for US reports after TIV-ID among persons vaccinated from July 1, 2011-February 28, 2013. Medical records were requested for reports coded as serious (death, hospitalization, prolonged hospitalization, disability, life-threatening-illness), and those suggesting anaphylaxis. Clinicians reviewed available information and assigned a primary clinical category to each report. Empirical Bayesian data mining was used to identify disproportional AE reporting following TIV-ID. Causality was not assessed.

RESULTS

VAERS received 466 reports after TIV-ID; 9 (1.9%) were serious, including one reported fatality in an 88-year-old vaccinee. Median age was 43 years (range 4-88 years). The most common AE categories were: 218 (46.8%) injection site reactions; 89 (19.1%) other non-infectious (comprised mainly of constitutional signs and symptoms); and 74 (15.9%) allergy. Eight reports (1.7%) of anaphylaxis were verified by the Brighton criteria or a documented physician diagnosis. Disproportional reporting was identified for three AEs: 'injection site nodule', 'injection site pruritus', and 'drug administered to patient of inappropriate age'. The findings for the first two AEs were expected. Twenty-four reports of vaccinees <18 years or ≥ 65 years were reported, and 14 of 24 were coded with the AE 'drug administered to patient of inappropriate age'.

CONCLUSIONS

Review of VAERS reports did not identify any new or unexpected safety concerns after TIV-ID. Injection site reactions were the most commonly reported AEs, similar to the pre-licensure clinical trials. Use of TIV-ID in younger and older individuals outside the approved age range highlights the need for education of healthcare providers regarding approved TIV-ID use.

Intussusception incidence among infants in the UK and Republic of Ireland: a pre-rotavirus vaccine prospective surveillance study

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The pre-rotavirus vaccine incidence of intussusception among UK and Irish infants was 24.8 and 24.2/100,000 live births.

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The highest incidence (50.3/100,000 live births) occurred in the fifth month of life (for England).

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A seasonal trend in intussusception was observed with the incidence significantly increased during winter and spring.

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Baseline rates will inform rotavirus vaccine-safety policy by enabling comparison with post-introduction incidence.

Introduction

Intussusception, an abdominal emergency in young children, has been linked to a previous vaccine used to prevent rotavirus gastroenteritis. Although this vaccine was withdrawn, recent studies have suggested a potential, very small increased risk of intussusception following the administration of newly developed rotavirus vaccines. We aimed to determine the baseline incidence of intussusception among infants in the UK and Republic of Ireland – prior to the imminent introduction of the rotavirus vaccine into the UK schedule this year.

Methods

Prospective, active surveillance via the established British Paediatric Surveillance Unit (BPSU) was carried out from March 2008 to March 2009. Clinicians across 101 National Health Service (and equivalent) hospitals, including 27 paediatric surgical centres, reported cases admitted for intussusception in the UK and Republic of Ireland. The standard Brighton Collaboration case definition was used with only definite cases included for incidence estimation.

Results

The study response rate was 94.5% (379 questionnaires received out of 401 case notifications). A total of 250 definite cases of intussusception were identified. The annual incidence among infants in the UK and Republic of Ireland was 24.8 (95% CI: 21.7–28.2) and 24.2 (95% CI: 15.0–37.0) per 100,000 live births. In the UK, the highest incidence occurred in Northern Ireland (40.6, 95% CI: 21.0–70.8), followed by Scotland (28.7, 95% CI: 17.5–44.3), England (24.2, 95% CI: 20.9–27.9), then Wales (16.9, 95% CI: 6.8–34.8). In England, regional incidence was highest in London and lowest in the West Midlands. By age, the highest incidence (50.3/100,000 live births, 95% CI: 33.4–72.7) occurred in the fifth month of life (for England). A seasonal trend in the presentation of intussusception was observed with the incidence significantly (p = 0.001) increased during winter and spring.

Conclusion

The baseline rates obtained in this study will inform rotavirus vaccine-safety policy by enabling comparison with post-introduction incidence.