Importance of background rates of disease in assessment of vaccine safety during mass immunisation with pandemic H1N1 influenza vaccines

Tetanus, diphtheria, acellular pertussis vaccine during pregnancy: pregnancy and infant health outcomes

OBJECTIVE

To assess pregnancy and birth outcomes in infants born to women who did or did not receive tetanus, diphtheria, acellular pertussis (Tdap) vaccine during pregnancy.

STUDY DESIGN

Retrospective cohort. Pregnant women 12-45 years of age who received Tdap at Intermountain Healthcare facilities and their infants were identified and compared with mother-infant pairs without documented Tdap from May 2005 through August 2009. Primary measures included pregnancy outcomes and infant health outcomes at birth through 12 months.

RESULTS

From 162,448 pregnancies we identified 138 women (0.08%) with documented Tdap administration during pregnancy (cases); 552 pregnant women without documented Tdap were randomly selected as controls. Of 138 immunized women, 63% received Tdap in the first trimester and 37% after. Tdap was given most commonly as wound prophylaxis. The incidence of spontaneous or elective abortion was no greater in Tdap cases than in controls. There were no significant differences in preterm delivery, gestational age, or birth weight between groups. One or more congenital anomaly was identified in 3.7% (95% CI 1.2%-8.5%) of case infants and 4.4% (95% CI 2.7%-6.5%) of control infants (P = .749). In infants born to women receiving Tdap during pregnancy, 3.6% (0.8%-10.2%) had International Classification of Diseases, Ninth Revision, Clinical Modification diagnoses consistent with complex chronic conditions within 12 months compared with 10.4% (95% CI 7.2%-14.4%) of infants of controls (P = .054).

CONCLUSIONS

Documented Tdap administration during pregnancy was uncommon and occurred most often in the first trimester as prophylaxis following trauma. No increase in adverse outcomes was identified in infants born to women receiving Tdap compared with infants of controls.

Safety of MF59-adjuvanted influenza vaccination in the elderly: results of a comparative study of MF59-adjuvanted vaccine versus nonadjuvanted influenza vaccine in northern Italy

MF59-adjuvanted trivalent influenza vaccine (Novartis Vaccines and Diagnostics, Siena, Italy) has been shown to be more effective than nonadjuvanted vaccine in the elderly population. Here we present results from a large-scale, observational, noninterventional, prospective postlicensure study that evaluated the safety of MF59-adjuvanted vaccine in elderly subjects aged 65 years or more. The study was performed in 5 northern Italian health districts during the 2006–2007, 2007–2008, and 2008–2009 influenza seasons. The choice of vaccine—either adjuvanted vaccine or a nonadjuvanted influenza vaccine—was determined by individual providers on the basis of local influenza vaccination policy. Hospitalizations for potential adverse events of special interest (AESIs) were identified from hospital databases and then reviewed against recognized case definitions to identify confirmed cases of AESI. Cumulative incidences were calculated for AESIs in predefined biologically plausible time windows, as well as in a 6-month window following vaccination. During the 3-year study period, 170,988 vaccine doses were administered to a total of 107,661 persons. Despite the large study size, cases of AESI resulting in hospitalization were rare, and risks of AESI were similar in both the MF59-adjuvanted and nonadjuvanted vaccination groups. In conclusion, similar safety profiles were observed for both nonadjuvanted and MF59-adjuvanted seasonal influenza vaccines in elderly recipients.

Recent developments and future directions in Guillain-Barré syndrome

Guillain-Barré syndrome (GBS) encompasses a spectrum of acquired neuropathic conditions characterized by inflammatory demyelinating or axonal peripheral neuropathy with acute onset. Clinical and experimental studies in the past years have led to substantial progress in epidemiology, pathogenesis of GBS variants, and identification of prognostic factors relevant to treatment. In this review we provide an overview and critical assessment of the most recent developments and future directions in GBS research.

Incidence of adverse events among healthcare workers following H1N1 Mass immunization in Ghana: a prospective study

BACKGROUND

Cases of the A(H1N1) 2009 influenza were first recorded in Ghana in July 2009. In June 2010 when prioritized vaccination against the novel A(H1N1) 2009 influenza virus started in the country, health workers were among the selected groups to receive the vaccination.

OBJECTIVE

The aim of this study was to determine the distribution and types of adverse events reported following immunization of healthcare workers at the Korle-Bu Teaching Hospital from the day vaccination started until 1 week after the end of vaccination.

METHODS

Safety data collected during the A(H1N1) 2009 influenza vaccination of health workers at the Korle-Bu Teaching Hospital (Accra, Ghana) were used for this study. All workers aged 18 years and over were eligible for vaccination. For uniformity, 0.5 mL of Pandemrix(®) (equivalent to 3.75 μg of hemagglutinin antigen) was administered intramuscularly into the deltoid muscle of the left arm. Each vaccinee was issued with a card and was advised to report any adverse events following immunization (AEFI) to designated health workers for follow-up. Incidence rates of adverse events were estimated and compared with the Pandemrix(®) Summary of Product Characteristics (SPC) RESULTS: A total of 5870 people (64.9 % females) with a mean age of 34.0 years were vaccinated. In total, 140 vaccinees reported adverse events. The mean age among vaccinees reporting adverse events was 36.1 years. The overall incidence of vaccinees reporting adverse events and the overall incidence of adverse events was 232 (95 % CI 199-320) per 10,000 people and 930 (95 % CI 820-1070) per 10,000 people, respectively. In particular, we found no difference in the way males reported AEFI compared with females (Chi-squared [χ(2)] = 0.59; p > 0.2), and we did not find any association between age as a categorical variable and vaccine adverse event reporting (χ(2) = 5.24; p > 0.1). There were only three serious cases that led to hospitalization. All three cases occurred within 24 hours of receiving the vaccine. The incidence rates for the various reported events were all lower compared with those in the Pandemrix(®) SPC, but while injection-site pain was the most frequent in the SPC and other foreign studies, we recorded headache as the most frequent. Even fatigue, muscle/joint aches and fever had higher incidence rates compared with injection-site pain. Tachycardia (n = 6), tinnitus (n = 1) and decreased appetite (n = 4) were reported although were not included in the SPC.

CONCLUSION

The most prominent adverse events reported were headaches, dizziness, muscle and joint aches, weakness, fever and injection-site pain. Although similar events were reported in other studies, the incidence was different and there were a few differences in the most frequently reported events. More studies of a similar nature should be encouraged in low- and medium-income countries to bridge the information gap with the developed world.

Vaccination and auto-immune rheumatic diseases: lessons learnt from the 2009 H1N1 influenza virus vaccination campaign

PURPOSE OF REVIEW

To determine the safety and efficacy of adjuvant and nonadjuvant influenza A/H1NI vaccination in patients with rheumatic diseases.

RECENT FINDINGS

Due to immune abnormalities and the use of steroids and immunosuppressant treatment, patients with rheumatic diseases are susceptible to infections including influenza. Infections continue to be one of the leading causes of morbidity and mortality in rheumatic diseases, partly due to the disease processes and partly due to medications. Viral infections are particularly an issue, so vaccinations would be advisable. However, because of the abnormalities in immune mechanisms in many rheumatic diseases, it is not clear whether vaccinations are well tolerated and effective. A number of studies confirmed the efficacy and safety of adjuvant and nonadjuvant influenza A/H1NI vaccination in patients with rheumatic diseases. The potential side effects associated with H1N1 vaccines were not different from those observed with seasonal influenza vaccine. The use of steroids and immunosuppressant therapies may alter the efficacy of the vaccines. Adjuvant and nonadjuvant influenza A/H1NI vaccinations have no clinically important effect on production or levels of autoantibodies in patients with rheumatic diseases.

SUMMARY

H1N1 vaccination should be given to patients with rheumatic diseases.

The expected number of background disease events during mass immunization in China

It is critical to distinguish events that are temporarily associated with, but not caused by, vaccination from those caused by vaccination during mass immunization. We performed a literature search in China National Knowledge Infrastructure and Pubmed databases. The number of coincident events was calculated based on its incidence rate and periods after receipt of a dose of hypothesized vaccine. We included background incidences of Guillain-Barré syndrome, anaphylaxis, seizure, sudden adult death syndrome, sudden cardiac death, spontaneous abortion, and preterm labour or delivery. In a cohort of 10 million individuals, 7.71 cases of Guillain-Barré syndrome would be expected to occur within six weeks of vaccination as coincident background cases. Even for rare events, a large number of events can be expected in a short period because of the large population targeted for immunization. These findings may encourage health authorities to screen the safety of vaccines against unpredictable pathogens.

Maternal safety of trivalent inactivated influenza vaccine in pregnant women

OBJECTIVE

To estimate the risks for medically attended events occurring within 42 days of receiving trivalent inactivated influenza vaccine and to evaluate specific risks of first-trimester vaccination.

METHODS

This retrospective observational cohort study compared rates of medically attended adverse events in trivalent inactivated influenza-vaccinated and unvaccinated pregnant women in the Vaccine Safety Datalink. Using a Poisson distribution and log link, we calculated maternal adjusted incident rate ratios for composite safety outcomes for the full cohort and the subset vaccinated during the first trimester.

RESULTS

The cohort included 75,906 vaccinated (28.4% in the first trimester) and 147,992 unvaccinated women matched by age, site, and pregnancy start date. In the first 3 days after vaccination, trivalent inactivated influenza vaccine was not associated with increased risk of specified medically attended events, including allergic reactions, cellulitis, and seizures (full cohort adjusted incident rate ratio 1.12, 95% confidence interval [CI] 0.81-1.55; P=.48; first-trimester adjusted incident rate ratio .97, 95% CI 0.53-1.78; P=.93). In the first 42 days, no incident cases of Guillain-Barré syndrome, optic neuritis, transverse myelitis, or Bells palsy were identified. Trivalent inactivated influenza vaccine was not associated with thrombocytopenia (full cohort adjusted incident rate ratio 0.90, 95% CI 0.68--1.19; P=.45; first-trimester adjusted incident rate ratio 0.56, 95% CI 0.22-1.39; P=.21) or an acute neurologic event (full cohort adjusted incident rate ratio 0.92, 95% CI 0.54-1.6; P=.75; first-trimester adjusted incident rate ratio 1.05, 95% CI 0.46-2.38; P=.91).

CONCLUSIONS

Receipt of trivalent inactivated influenza vaccine during pregnancy was not associated with increased risk of adverse events in the 42 days after vaccination, supporting its safety for the mother.

Mortality rates and cause-of-death patterns in a vaccinated population

BACKGROUND

Determining the baseline mortality rate in a vaccinated population is necessary to be able to identify any unusual increases in deaths following vaccine administration. Background rates are particularly useful during mass immunization campaigns and in the evaluation of new vaccines.

PURPOSE

Provide background mortality rates and describe causes of death following vaccination in the Vaccine Safety Datalink (VSD).

METHODS

Analyses were conducted in 2012. Mortality rates were calculated at 0-1 day, 0-7 days, 0-30 days, and 0-60 days following vaccination for deaths occurring between January 1, 2005, and December 31, 2008. Analyses were stratified by age and gender. Causes of death were examined, and findings were compared to National Center for Health Statistics (NCHS) data.

RESULTS

Among 13,033,274 vaccinated people, 15,455 deaths occurred between 0 and 60 days following vaccination. The mortality rate within 60 days of a vaccination visit was 442.5 deaths per 100,000 person-years. Rates were highest in the group aged ≥85 years, and increased from the 0-1-day to the 0-60-day interval following vaccination. Eleven of the 15 leading causes of death in the VSD and NCHS overlap in both systems, and the top four causes of death were the same in both systems.

CONCLUSIONS

VSD mortality rates demonstrate a healthy vaccinee effect, with rates lowest in the days immediately following vaccination, most apparent in the older age groups. The VSD mortality rate is lower than that in the general U.S. population, and the causes of death are similar.

Safety of meningococcal polysaccharide-protein conjugate vaccine in pregnancy: a review of the Vaccine Adverse Event Reporting System

OBJECTIVE

We characterized reports to the Vaccine Adverse Event (AE) Reporting System (VAERS) of pregnant women who received meningococcal polysaccharide-protein conjugate vaccine Menactra (MenACWY-D; Sanofi Pasteur Inc., Swiftwater, PA).

STUDY DESIGN

We searched VAERS for reports of pregnant women who received MenACWY-D from Jan. 1, 2005 through Dec. 31, 2011. We conducted clinical review of reports and available medical records.

RESULTS

Of 103 identified reports, 38 (36.7%) did not describe any AE. No maternal or infant deaths were reported. The most frequent pregnancy-specific AE was spontaneous abortion in 17 (16.5%) reports. Urinary tract infections and fever with vomiting were the most frequent nonpregnancy-specific AEs found in 4 (3.9%) and 3 (2.9%) reports, respectively. We identified 1 report with a major congenital anomaly (aqueductal stenosis and severe ventriculomegaly).

CONCLUSION

Our comprehensive review of reports to VAERS in pregnant women after MenACWY-D did not identify any concerning patterns in maternal, infant, or fetal outcomes.

Safety of pandemic (H1N1) 2009 monovalent vaccines in taiwan: a self-controlled case series study

In Taiwan, new H1N1 monovalent vaccines without adjuvant and with MF59® adjuvant were used in the nationwide vaccination campaign beginning on November 1, 2009. From November 2009 through February 2010, the authors identified recipients of H1N1 vaccines who were diagnosed with adverse events of special interest (AESIs) in a large-linked safety database, and used the self-controlled case series (SCCS) method to examine the risk of each AESI in the 0–42 days after H1N1 vaccination. Of the 3.5 million doses of H1N1 vaccines administered and captured in the linked database, the SCCS analysis of Guillain-Barré syndrome (GBS) found an incidence rate ratio of 3.81 (95% confidence interval 0.43–33.85) within 0–42 days after nonadjuvanted H1N1 vaccination and no cases after MF59®-adjuvanted H1N1 vaccination. The risks of other AESIs were, in general, not increased in any of the predefined postvaccination risk periods and age groups. The databases and infrastructure created for H1N1 vaccine safety evaluation may serve as a model for safety, effectiveness and coverage studies of licensed vaccines in Taiwan.

Safety of seasonal influenza and influenza A (H1N1) 2009 monovalent vaccines in pregnancy

Inactivated influenza vaccines have been given to pregnant women since 1964. Since 2004, the Advisory Committee on Immunization Practices has recommended that pregnant women receive trivalent inactivated influenza vaccine at any time during pregnancy. Studies conducted before 2009 did not identify any safety concerns after trivalent inactivated influenza vaccine in mothers or their infants. During the 2009-2010 influenza A (H1N1) influenza vaccination program, several monitoring systems were established or enhanced to assess whether adverse events were associated with H1N1 2009 monovalent vaccines (2009 H1N1 influenza vaccines). Data from these systems did not identify any safety concerns in pregnant women who received 2009 H1N1 influenza vaccines or their infants. Although live attenuated influenza vaccines are not recommended in pregnant women, a small number of studies have not shown any safety concern among pregnant women or their infants who were inadvertently exposed to these vaccines. This review summarizes US and international safety data for influenza vaccines in pregnant women with an emphasis on 2009 H1N1 influenza vaccines.

The incidence of narcolepsy in Europe: before, during, and after the influenza A(H1N1)pdm09 pandemic and vaccination campaigns

BACKGROUND

In August 2010 reports of a possible association between exposure to AS03 adjuvanted pandemic A(H1N1)pdm09 vaccine and occurrence of narcolepsy in children and adolescents emerged in Sweden and Finland. In response to this signal, the background rates of narcolepsy in Europe were assessed to rapidly provide information for signal verification.

METHODS

We used a dynamic retrospective cohort study to assess the narcolepsy diagnosis rates during the period 2000-2010 using large linked automated health care databases in six countries: Denmark, Finland, Italy, the Netherlands, Sweden and the United Kingdom.

RESULTS

Overall, 2608 narcolepsy cases were identified in almost 280 million person years (PY) of follow up. The pooled incidence rate was 0.93 (95% CI: 0. 90-0.97) per 100,000 PY. There were peaks between 15 and 30 year of age (women>men) and around 60 years of age. In the age group 5-19 years olds rates were increased after the start of pandemic vaccination compared to the period before the start of campaigns, with rate ratios (RR) of 1.9 (95% CI: 1.1-3.1) in Denmark, 6.4 (95% CI: 4.2-9.7) in Finland and 7.5 (95% CI: 5.2-10.7) in Sweden. Cases verification in the Netherlands had a significant effect on the pattern of incidence over time.

CONCLUSIONS

The results of this incidence study provided useful information for signal verification on a population level. The safety signal of increased narcolepsy diagnoses following the start of the pandemic vaccination campaign as observed in Sweden and Finland could be observed with this approach. An increase in narcolepsy diagnoses was not observed in other countries, where vaccination coverage was low in the affected age group, or did not follow influenza A(H1N1)pdm09 vaccination. Patient level analyses in these countries are being conducted to verify the signal in more detail.

Pharmacoepidemiology

Current concerns over the safety of medicines once they have been marketed mean that pharmacoepidemiology is of increasing importance. There are three main areas in which further research is needed. 1 To improve the methods used to make causal inference of effects of medicines and to raise the quality of the reporting and critical appraisal tools, so that the strengths and weaknesses of the new methods can be judged. 2 To apply the methods in areas where randomized trials cannot easily be done, such as in pregnancy. 3 To use electronic health records as fully as possible, using linkage between different databases, ensuring the data are of as high quality as possible. Public health and public perceptions mean that much of pharmacoepidemiology must be done using non-industry funding sources.

Viral invasion of the amniotic cavity (VIAC) in the midtrimester of pregnancy

INTRODUCTION

The prevalence of viral infections in the amniotic fluid (AF) has not yet been ascertained. The aim of this study was to determine the prevalence of specific viral nucleic acids in the AF and its relationship to pregnancy outcome.

STUDY DESIGN

From a cohort of 847 consecutive women undergoing midtrimester amniocentesis, 729 cases were included in this study after exclusion of documented fetal anomalies, chromosomal abnormalities, unavailability of AF specimens and clinical outcomes. AF specimens were tested by quantitative real-time PCR for the presence of genome sequences of the following viruses: adenoviruses, herpes simplex virus (HSV), varicella zoster virus (VZV), human herpesvirus 6 (HHV6), human cytomegalovirus (HCMV), Epstein-Barr virus (EBV), parvovirus B19 and enteroviruses. Viral nucleic acid testing was also performed in maternal blood and cord blood in the population of women in whom AF was positive for viruses and in a control group of 29 women with AF negative for viral nucleic acids. The relationship between the presence of viruses and pregnancy and neonatal outcome was examined. The correlation between the presence of nucleic acids of viruses in the AF and the concentration of the cytokine interleukin-6 (IL-6) and the T cell chemokine CXCL-10 (or IP-10) in AF and maternal blood were analyzed.

RESULTS

Viral genome sequences were found in 16 of 729 (2.2%) AF samples. HHV6 was the most commonly detected virus (7 cases, 1.0%), followed by HCMV (6 cases, 0.8%), parvovirus B19 (2 cases, 0.3%) and EBV (1 case, 0.1%), while HSV, VZV, enteroviruses and adenoviruses were not found in this cohort. Corresponding viral DNA was also detected in maternal blood of six out of seven women with HHV6-positive AF and in the umbilical cord plasma, which was available in one case. In contrast, viral DNA was not detected in maternal blood of women with AF positive for parvovirus B19, HCMV, EBV or of women with AF negative for viruses. HHV6 genome copy number in AF and maternal blood was consistent with genomic integration of viral DNA and genetic infection in all women. There was no significant difference in the AF concentration of IL-6 and IP-10 between patients with and without VIAC. However, for HCMV, there was a significant relationship between viral copy number and IP-10 concentration in maternal blood and AF. The group of women with AF positive for viral DNA delivered at term healthy neonates without complications in 14 out of 16 cases. In one case of HHV6 infection in the AF, the patient developed gestational hypertension at term, and in another case of HHV6 infection in the AF, the patient delivered at 33 weeks after preterm premature rupture of membranes (PPROM).

CONCLUSION

Viral nucleic acids are detectable in 2.2% of AF samples obtained from asymptomatic women in the midtrimester. HHV6 was the most frequently detected virus in AF. Adenoviruses were not detected. Vertical transmission of HHV6 was demonstrated in one case.

Use of population based background rates of disease to assess vaccine safety in childhood and mass immunisation in Denmark: nationwide population based cohort study

OBJECTIVES

To predict the number of selected outcomes temporally associated but not caused by vaccination, to aid causality assessment of adverse events arising after mass immunisation in a paediatric population.

DESIGN

Nationwide population based cohort study.

SETTING

Denmark.

PARTICIPANTS

All liveborn infants delivered after 1 January 1980. Study population was followed from date of birth until hospital admission for selected outcome diagnoses, death, first emigration, age 18 years, or 31 December 2009. The study population was subject to vaccines used in standard childhood immunisation in Denmark, with 82-93% vaccine coverage.

MAIN OUTCOME MEASURES

Incidence of acute infectious and post-infectious polyneuritis (Guillain-Barré syndrome), acute transverse myelitis, optic polyneuritis, facial nerve palsy, anaphylactic shock, seizure, multiple sclerosis, autoimmune thrombocytopenia, type 1 diabetes mellitus, juvenile and rheumatoid arthritis, narcolepsy, and death of unknown cause stratified by sex, age, and season. We predicted the number of events for a hypothetical vaccine cohort of 1,000,000 people for follow-up periods of up to 182 days.

RESULTS

The study included 2,300,227 liveborn infants, yielding 37,262,404 person years of follow-up; median follow-up was 16.8 person years. Incidence of outcome diagnoses spanned from 0.32 per 100,000 patient years for autoimmune thrombocytopenia to 189.82 per 100,000 patient years for seizure. Seasonal differences were most pronounced for anaphylactic shock, seizure, and multiple sclerosis. Even for rare outcomes, numerous events were predicted in the hypothetical vaccine cohort. We predicted that 20 cases of type 1 diabetes mellitus, 19 of juvenile or rheumatoid arthritis, eight of facial nerve palsy, and five of multiple sclerosis per 1,000,000 children would occur within 42 days after vaccination.

CONCLUSIONS

Incorporating exact background rates of disease based on age, sex, and seasonal distribution could strengthen vaccine safety assessment, and provides an evidence based focus for discussing the incremental risk of newly introduced vaccines.

A prospective observational safety study on MF59(®) adjuvanted cell culture-derived vaccine, Celtura(®) during the A/H1N1 (2009) influenza pandemic

BACKGROUND

The present study was a prospective observational study to evaluate the safety profile of Celtura(®), a monovalent, cell culture-derived, inactivated subunit influenza vaccine prepared from A/California/07/2009(H1N1) with the adjuvant MF59(®). Subjects were enrolled prospectively during the H1N1 2009 influenza pandemic at medical centres in Colombia, Chile, Switzerland, and Germany during the period December 2009 to June 2010.

METHODS

Subjects ages 18 and older were followed for the occurrence of adverse events (AEs) for six months after vaccination. Adverse events of special interest (AESIs) were neuritis, convulsion (seizure), anaphylaxis, encephalitis, vasculitis, Guillain-Barre syndrome, demyelinating conditions, Bell's palsy, and laboratory-confirmed vaccination failure.

RESULTS

Overall, 7348 AEs were reported in 2296 of 3989 enrolled subjects (57.6%). Only two AEs were considered related to injection site reactions. No laboratory-confirmed cases of influenza were reported. There were 108 medically confirmed serious adverse events (SAEs) reported among 73 subjects with 6 such SAEs described as possibly or probably related to vaccination. Three fatal cases were reported and assessed as not related to vaccination. Two AESIs classified as convulsion were reported and assessed as not related to vaccination. Both AESIs occurred well outside the pre-specified 7 day risk window representing the likely timeframe of the occurrence of seizure following vaccination.

CONCLUSIONS

The results of this study support the overall good safety profile of MF59 adjuvanted cell culture-derived influenza vaccine as administered in adults during the 2009-2010 H1N1 influenza pandemic. No concern is raised regarding the occurrence of AESIs.

Polymyositis following Pandemic Influenza A (H1N1) and 2009-10 Seasonal Trivalent Vaccines

Sporadic associations between inflammatory myopathies with vaccinations were described in the literature, raising the possible trigger value of vaccines in the development of these autoimmune disorders. Here, we reported the clinical history of 3 patients who developed polymyositis complicated by interstitial lung disease (2 cases) and dermatomyositis (1 case), after influenza A (H1N1) vaccination.

A population based cohort study to assess the safety of pandemic influenza vaccine Focetria in Emilia-Romagna region, Italy - part two

INTRODUCTION

A two phases post authorization safety and effectiveness study of individuals vaccinated with the MF59-adjuvanted A/H1N1 influenza vaccine, Focetria (Novartis Vaccines & Diagnostics, Siena, Italy), was conducted in Emilia-Romagna region, Italy during the 2009 A/H1N1 influenza pandemic. The second phase study aim was to detect short- and long-term adverse events of special interest (AESIs) following vaccination, and to measure vaccine effectiveness in term of hospital admissions.

STUDY DESIGN AND METHOD

A population-based cohort study using record linkage of automated healthcare databases is described. Focetria was administered to 127,522 subjects between October 2009 and February 2010. Vaccinated subjects were generally less healthy than unvaccinated ones. Propensity to be vaccinated was calculated for each subject, and vaccinated and unvaccinated subjects were matched accordingly (103,642 subjects in each group). AESIs were validated against clinical records.

RESULTS

In the overall (pre-matching) cohort, a total of 504 short-term incident AESIs (28 in 127,522 vaccinated and 476 in 3,967,917 unvaccinated subjects) were registered (unadjusted OR: 1.8; 95% CI: 1.2, 2.7). No fatalities were recorded. In the matched cohort, a total of 26 short-term incident AESIs (11 in the vaccinated and 15 in the unvaccinated group) were registered, with no differences between groups (OR: 0.7; 95% CI: 0.3, 1.6). Most frequent short-term incident AESIs were convulsions (4 out of 11), and demyelinating diseases (3 out of 11). In the long-term a total of 121 incident AESIs (60 in the vaccinated and 61 in the unvaccinated group) were registered, with no differences between groups (OR: 1.0; 95% CI: 0.7, 1.4). Most common long-term incident AESIs were demyelinating diseases (21 out of 60), and vasculitis (13 out of 60). Vaccine effectiveness was not assessed as the majority of subjects were vaccinated at the end of the pandemic peak and few cases (<0.1%) had laboratory confirmation.

CONCLUSIONS

This population-based cohort study using automated databases suggests that Focetria is not associated with an increase in AESIs.

Influenza H1N1 (swine flu) vaccination: a safety surveillance feasibility study using self-reporting of serious adverse events and pregnancy outcomes

AIMS

During the global H1N1 influenza A (swine flu) pandemic 2009–2010, swine flu vaccines were expeditiously licensed and a mass vaccination programme for high risk groups, including pregnant women, was introduced in the UK. This pilot active safety surveillance study was performed to establish the feasibility of rapidly monitoring the new swine flu vaccines in large patient numbers receiving or offered the vaccination under normal conditions of use within a short time frame.

METHODS

A cohort design with safety data capture through modern technologies was carried out in Scotland, UK during the winter swine flu vaccination programme 2009–2010 in individuals receiving or offered the swine flu vaccination. The main outcome measures were self-reported serious adverse events (SAEs) and pregnancy outcomes.

RESULTS

The cohort comprised 4066 people; 3754 vaccinated and 312 offered the vaccination but not vaccinated. There were 939 self-reported events (838 different events), 53 judged to fit SAE criteria by the investigators, with nine judged as possibly, probably or definitely vaccine related. None of the seven deaths (six in vaccinees) were judged as vaccine related. One hundred and twenty-eight women reported 130 pregnancies during the study with 117 pregnant at study start. There were reports of four miscarriages in three women and six possible congenital abnormalities in live births.

CONCLUSIONS

Overall, no significant safety issues were identified. The methodology and use of modern technologies to collect safety data from large numbers of patients was successful and could be used again in similar safety studies.

Adverse event reports after tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccines in pregnant women

OBJECTIVE

We sought to characterize reports to the Vaccine Adverse Event Reporting System (VAERS) of pregnant women who received tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccine (Tdap).

STUDY DESIGN

We searched VAERS for reports of pregnant women who received Tdap from Jan. 1, 2005, through June 30, 2010. We conducted a clinical review of reports and available medical records.

RESULTS

We identified 132 reports of Tdap administered to pregnant women; 55 (42%) described no adverse event (AE). No maternal or infant deaths were reported. The most frequent pregnancy-specific AE was spontaneous abortion in 22 (16.7%) reports. Injection site reactions were the most frequent non-pregnancy-specific AE found in 6 (4.5%) reports. One report with a major congenital anomaly (gastroschisis) was identified.

CONCLUSION

During a time when Tdap was not routinely recommended in pregnancy, review of reports to VAERS in pregnant women after Tdap did not identify any concerning patterns in maternal, infant, or fetal outcomes.

Declining Guillain-Barré syndrome after campylobacteriosis control, New Zealand, 1988-2010

Food safety measures that lower incidence of campylobacteriosis might also prevent Guillain-Barré syndrome.

The Perception Gap: Recognizing and managing the risks that arise when we get risk wrong

Many in the academic, science, and business communities are frustrated at how people perceive and respond to risk, lamenting that the lay public is sometimes more afraid of some threats than the evidence warrants, and less afraid of some dangers than the evidence warns. This is often ascribed to the alarmist way the news media cover risk-related subjects. That criticism is simplistic and unproductive, and ignores or dismisses the large body of research that finds that the perception of risk is not, and can never be, perfectly rational. Risk perception among members of the public, the media, and members of the academic, scientific, and business communities, is ultimately subjective. The gap between our fears and the evidence is not simply the product of alarmist media reporting. This 'Perception Gap' poses significant risks in and of itself, influencing the choices we make as individuals and as a society. The roots of the Perception Gap must be understood if we are to recognize the dangers that can arise when we sometimes get risk wrong, and in order that we may more wisely manage those risks as actively as we manage toxicological or food or other risks with which we are more familiar.

Anti-ganglioside antibodies were not detected in human subjects infected with or vaccinated against 2009 pandemic influenza A (H1N1) virus

Recipients of influenza A (H1N1) vaccine in 1976 had an increased risk for the neurologic disorder Guillain-Barré syndrome (GBS). Anti-ganglioside antibodies, which might be associated with the development of GBS, were previously reported to be induced in mice immunized with an H1N1 vaccine of 1976 or another influenza vaccine. In this study we analyzed anti-ganglioside antibodies in human subjects infected with or vaccinated against 2009 pandemic H1N1, including eight patients diagnosed to have post-vaccination GBS. Antibodies against GM1 or another ganglioside were not detected in any subject or in vaccinated mice. Our results did not support the induction of anti-ganglioside antibodies by influenza viruses or vaccines.

Increase in reported adverse events following seasonal influenza vaccination among the French armed forces, 2008-2009: possible role of stimulated reporting and background cases of influenza-like infection

OBJECTIVES

In September 2009, an increase in seasonal influenza vaccine adverse events (VAE), compared with reports for previous years, was detected among the French armed forces in the setting of an extended immunization campaign. This work presents the results of this investigation.

STUDY DESIGN

VAE were surveyed among all French military personnel from 2008 to 2009 by Epidemiological Departments of the French Military Health Service. For each case, a notification form was completed, providing patient and clinical information.

METHODS

Case definitions were derived from the French drug vigilance guidelines. Three types of VAE were considered: non-serious, serious and unexpected. Incidence rates were calculated by relating VAE to the number of vaccine doses injected.

RESULTS

Forty-seven seasonal influenza VAE were reported in continental France: 18 in 2008 and 29 in 2009. The annual reporting rate was higher in 2009 (31.6 vs 16.6 VAE per 100,000 injections, respectively). The highest monthly incidence was observed in September 2009 (60.8 events per 100,000 injections). Two other peaks were observed in February 2008 and March 2009. The incidence in September 2009 was not significantly different from the incidences in February 2008 and March 2009. It was observed that incidence peaks occurred during influenza epidemic periods. One serious neurological VAE was observed.

CONCLUSIONS

The increase in seasonal influenza VAE in late 2009 mainly involved non-serious events, and could reflect stimulated reporting in the context of the A(H1N1)pdm09 pandemic. VAE reporting rates were highest during influenza epidemic periods, which could be explained by VAE being wrongly attributed to the vaccine when symptoms could reflect coincident background cases of viral infection.

Patient reported outcome data following influenza A (H1N1p) vaccination in the 2009-2010 season: web-based and telephone evaluation

Background

There has been worldwide interest in the safety of the pandemic influenza A (H1N1p) vaccines, although limited data are available from the vaccine recipients’ perspective. This evaluation was designed to collect data from people who had received an influenza vaccination during the 2009–2010 season using a web-based data collection tool supplemented by telephone reporting (PROBE).

Methods

People scheduled to receive the influenza A (H1N1p) or seasonal influenza vaccines were recruited through media advertising and campaigns throughout the West of Scotland. Vaccine recipients participated in the evaluation by answering demographic and side effect questions using PROBE methodology on the day of the immunization, after 3 days, 8 days, 6 weeks, 12 weeks, and 26 weeks.

Results

A total of 1103 vaccine recipients including 134 young children (0–4 years) participated in the evaluation; 694 (63%) received H1N1p vaccine only, 135 (12%) seasonal vaccine only, 224 (20%) both H1N1p and seasonal vaccines, and 50 (5%) received H1N1p or seasonal vaccine with a non-influenza vaccine (eg, travel or pneumococcal). Overall, 42% of recipients reported experiencing a side effect after their baseline vaccination; the most commonly reported were general and arm side effects (>20%). Injection site discomfort/pain and flu-like symptoms were reported by 57% and 24% of recipients, respectively. A significantly higher proportion of the 960 H1N1p vaccine recipients experienced a side effect (44% vs 27%, P < 0.001) or injection site discomfort/pain (61% vs 26%, P < 0.001) than those receiving seasonal influenza vaccines. Female sex and H1N1p vaccination were associated with a significantly higher risk of injection site discomfort/pain, whereas the 70+ age group was associated with a significantly lower risk. H1N1p vaccine was well tolerated by children under 5 years with side effects reported at a similar frequency to that found in the total population.

Conclusions

Safety and tolerability data from influenza vaccine recipients including young children (via parents/carers) can be effectively collected using an online questionnaire with a telephone option (PROBE). The influenza A (H1N1p) vaccine was well tolerated, but was associated with more local short-term reactions than the seasonal influenza vaccine.

Health problems most commonly diagnosed among young female patients during visits to general practitioners and gynecologists in France before the initiation of the human papillomavirus vaccination program

PURPOSE

Background rates for common health problems have seldom been estimated to facilitate interpretation of signals that may occur after a new public health intervention. Background rates of diagnoses from general practitioners (GPs) and gynecologists (GYNs) were assessed before the implementation of human papillomavirus (HPV) immunization program.

METHODS

This cross-sectional study used data collected in 2006 in France. All visits of women (aged 11-23 years) to a GP or a GYN participating in the longitudinal patient data (LPD) network were considered. Diagnoses and symptoms were retrieved and classified according to the International Classification of Primary Care. Only diagnoses made in ≥ 1% of visits were reported in primary analyses. Independent analyses were performed for visits to GPs and GYNs and for adolescents and young adults. Finally, the rates of pre-specified health problems of interest (e.g., because of their potential identification as signals after HPV immunization) were computed from processed diagnostic data, using time windows consistent with HPV vaccination scheme.

RESULTS

About 380,813 GP and 36,329 GYN visits were analyzed. Acute upper respiratory infections were the most frequently recorded diagnoses by GPs, accounting for 11,783 per 100,000 visits per year. Visits related to the respiratory system accounted for 10 of the 23 most frequent diagnoses by GPs. Genital candidiasis was the most frequent GYN diagnosis, accounting for 4746 per 100,000 visits per year. Most GYN visits were for pregnancy-related issues or menstrual problems. The main diagnoses were similar in adolescents compared with young adults in both GP and GYN settings. Pre-specified health problems occurred at high rates, as exemplified by acne that was diagnosed in 0.8% of patients during time windows consistent with HPV immunization.

CONCLUSION

Diagnostic data processed from electronic health records identified the rates of common health events experienced by young female patients routinely visiting their GP or GYN before HPV immunization. Such rates may prove useful in interpreting adverse events reported after the launch of new medical interventions.

Adverse events following administration to pregnant women of influenza A (H1N1) 2009 monovalent vaccine reported to the Vaccine Adverse Event Reporting System

OBJECTIVE

The objective of the study was to evaluate and summarize reports to the Vaccine Adverse Event Reporting System (VAERS), a spontaneous reporting system, in pregnant women who received influenza A (H1N1) 2009 monovalent vaccine to assess for potential vaccine safety problems.

STUDY DESIGN

We reviewed reports of adverse events (AEs) in pregnant women who received 2009-H1N1 vaccines from Oct. 1, 2009, through Feb. 28, 2010.

RESULTS

VAERS received 294 reports of AEs in pregnant women who received 2009-H1N1 vaccine: 288 after inactivated and 6 after the live attenuated vaccines. Two maternal deaths were reported. Fifty-nine women (20.1%) were hospitalized. We verified 131 pregnancy-specific outcomes: 95 spontaneous abortions (<20 weeks); 18 stillbirths (≥20 weeks); 7 preterm deliveries (<37 weeks); 3 threatened abortions; 2 preterm labor; 2 preeclampsia; and 1 each of fetal hydronephrosis, fetal tachycardia, intrauterine growth retardation, and cleft lip.

CONCLUSION

Review of reports to VAERS following H1N1 vaccination in pregnant women did not identify any concerning patterns of maternal or fetal outcomes.

Events temporarily associated with anti-influenza A (H1N1) vaccination in Mexico

BACKGROUND AND AIMS

In Mexico from December 2009 to June 2010, 45,490,501 doses of the vaccine against the influenza virus were administered; 27,048,330 of those corresponded to influenza A (H1N1) and 18,442,171 to seasonal influenza. Therefore, the assessment of events temporarily associated with vaccination (ETAV) is mandatory.

METHODS

The database corresponding to the ETAV associated with influenza (A [H1N1] and seasonal) immunization reported between December 2009 and June 2010 was analyzed. Patients who displayed at least one ETAV with one of the following schedules were included: A) influenza A (H1N1) vaccine, B) seasonal influenza vaccine, C) influenza A (H1N1) vaccine and seasonal influenza vaccine.

RESULTS

A total of 597 ETAVs were reported. The 20- to 49-year-old age group was the most affected one (52.9%). The ETAV notification rate for influenza A (H1N1) vaccination was 1.41/100,000 applied doses vs. 0.74/100,000 applied doses corresponding to the seasonal influenza vaccination. Fifty seven events were considered serious (14 corresponded to Guillain-Barré syndrome) and these were considered coincidental unrelated events.

CONCLUSIONS

There is no evidence of an increased rate of Guillain-Barré Syndrome with respect to the cases expected in the general population.

Guillain-Barré syndrome and H1N1 (2009) pandemic influenza vaccination using an AS03 adjuvanted vaccine in the United Kingdom: self-controlled case series

In 1976 a swine influenza vaccine was associated with an increased risk of Guillain-Barré syndrome (GBS). Although subsequent studies did not find an increased risk of GBS following seasonal influenza vaccine, there was concern that the monovalent H1N1 vaccines developed against the swine influenza pandemic of 2009 might increase the risk of GBS. In the UK a split-virion AS03 oil-in-water adjuvanted vaccine (Pandemrix™) was predominantly used. To determine whether the risk of GBS increased after Pandemrix administration, we sought GBS cases during the period of vaccine use from neurologists and a patient support group, and following the vaccination period from hospital episode statistics (HES) in England. We obtained cases' vaccination histories and illness onset dates from general practitioners. We determined the relative incidence of GBS in the 6 weeks after vaccination using the self-controlled case series method on the cases identified in HES. We included 327 GBS cases, of whom 37 received pandemic vaccine in the study period, nine of whom developed GBS within 6 weeks of vaccination (relative incidence 1.05 [95% confidence interval (CI) 0.37 to 2.24]). We found no evidence of an increased risk of GBS in the 6 weeks following pandemic influenza vaccination.

Adverse events after tetanus toxoid, reduced diphtheria toxoid and acellular pertussis (Tdap) vaccine administered to adults 65 years of age and older reported to the Vaccine Adverse Event Reporting System (VAERS), 2005-2010

BACKGROUND

Tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine was not licensed for use in adults aged ≥65 years due to lack of sufficient efficacy and safety data.

OBJECTIVE

To characterize reports to the Vaccine Adverse Event Reporting System (VAERS) among adults aged ≥65 years who received Tdap vaccine 'off-label' to assess for potential vaccine safety concerns.

METHODS

We searched VAERS for US reports of adverse events (AEs) in subjects aged ≥65 years who received Tdap vaccine from 9/1/2005 to 9/08/2010. Medical records were requested for all reports coded as serious (death, hospitalization, prolonged hospitalization, permanent disability, life-threatening-illness). Proportional reporting ratio (PRR) was used to assess for higher proportionate reporting for AEs after Tdap compared with Td reports in subjects aged ≥65 years.

RESULTS

VAERS received 243 reports following Tdap administered to persons aged ≥65 years. Eleven (4.5%) reports were serious, including two deaths. Most common AEs were local reactions in 100 (41.2%) reports. Seventy-eight (32.1%) reports contained coding terms that denoted inappropriate administration of vaccine. 'Cough' was the only term associated with disproportionately higher reporting after Tdap compared with Td. Six of seven Tdap reports containing the term 'Cough' were non-serious. Clinical review of serious reports identified no unusual patterns of AEs.

CONCLUSION

Our VAERS review of the 'off-label' use of Tdap vaccine in adults ≥65 years did not find any safety concerns that warrant further study. These data will provide useful baseline information to assist CDC and FDA with monitoring efforts as permissive recommendations for Tdap in older persons are adopted.

Causality assessment of serious neurologic adverse events following 2009 H1N1 vaccination

BACKGROUND

Adverse events occurring after vaccination are routinely reported to the Vaccine Adverse Event Reporting System (VAERS). We studied serious adverse events (SAEs) of a neurologic nature reported after receipt of influenza A (H1N1) 2009 monovalent vaccine during the 2009-2010 influenza season. Investigators in the Clinical Immunization Safety Assessment (CISA) network sought to characterize these SAEs and to assess their possible causal relationship to vaccination.

METHODS

Centers for Disease Control and Prevention (CDC) and Food and Drug Administration (FDA) physicians reviewed all SAE reports (as defined by the Code of Federal Regulations, 21CFR§314.80) after receipt of H1N1 vaccine reported to VAERS between October 1, 2009 and March 31, 2010. Non-fatal SAE reports with neurologic presentation were referred to CISA investigators, who requested and reviewed additional medical records and clinical information as available. CISA investigators assessed the causal relationship between vaccination and the event using modified WHO criteria as defined.

RESULTS

212 VAERS reports of non-fatal serious neurological events were referred for CISA review. Case reports were equally distributed by gender (50.9% female) with an age range of 6 months to 83 years (median 38 years). The most frequent diagnoses reviewed were: Guillain-Barré Syndrome (37.3%), seizures (10.8%), cranial neuropathy (5.7%), and acute disseminated encephalomyelitis (3.8%). Causality assessment resulted in classification of 72 events as "possibly" related (33%), 108 as "unlikely" related (51%), and 20 as "unrelated" (9%) to H1N1 vaccination; none were classified as "probable" or "definite" and 12 were unclassifiable (6%).

CONCLUSION

The absence of a specific test to indicate whether a vaccine component contributes to the pathogenesis of an event occurring within a biologically plausible time period makes assessing causality difficult. The development of standardized protocols for providers to use in evaluation of adverse events following immunization, and rapid identification and follow-up of VAERS reports could improve causality assessment.