Pre-Vaccination Care-Seeking in Females Reporting Severe Adverse Reactions to HPV Vaccine. A Registry Based Case-Control Study

Risk of infectious mononucleosis is not associated with prior infection morbidity

Background

The probability of presenting with infectious mononucleosis (IM) upon primary Epstein-Barr virus infection increases dramatically at the start of puberty. Aiming to understand why that is, we assessed whether the number of infection-related health events during two specific time periods-ages 10-12 years (pre-teen window) and the three most recent years (recent window)-could predict the likelihood of individuals aged 13-19 years developing IM.

Methods

We used sibship-stratified Cox regression to mitigate socio-demographic confounding and bias. Consequently, we only followed members of IM-affected sibships aged 13-19 years between 1999 and 2021 for IM, based on information from complete nationwide Danish administrative and health registers. Estimates were further adjusted for sex, age, birth order (1, 2, 3+) and sibship constellation [number of siblings and their signed (older/younger) age difference to the index person]. Infection-related health events defining the exposures considered were either a category of antimicrobial prescription, or a hospital contact with an infectious disease diagnosis. We measured evidence/probability of the associations using asymptotic Bayes factors, rather than using p-value based testing.

Results

The adjusted hazard ratio (HR) for IM with 95% confidence limits for an additional antimicrobial prescription in the pre-teen exposure window was [1.01; 0.98-1.04], and the corresponding adjusted HR for an additional antimicrobial prescription in the recent exposure window was [1.02; 0.99-1.06].

Conclusions

IM was not preceded by unusual numbers of infections. Small effect sizes, together with small variation in exposure, did not render the assessed exposures useful for predicting IM for public health or the clinic.

The Association of a Lower Risk of Fibromyalgia with Human Papillomavirus Vaccination: A Retrospective Cohort Study from the TriNetX US Collaborative Network

OBJECTIVE

Remarkably similar symptoms have been observed between fibromyalgia patients and those who present adverse events after HPV vaccination. However, no research has been conducted on their association.

METHODS

Using data from the US collaborative network within the TriNetX network, we identified all the females who had had an HPV vaccination within 1 year before an index date falling between 2016 and 2023. We selected a propensity-score-matched (PSM, 1:1 ratio), non-HPV-vaccinated cohort as the comparator. Both cohorts were followed up from 1 day after the index date until the diagnosis of incidental fibromyalgia or until the patient was lost to the follow-up process or until the end of 2023.

RESULTS

After PSM, a total of 421,564 females in the HPV-vaccinated cohort and 421,564 females in the non-HPV-vaccinated cohort were included in the study. Significantly lower risks of developing fibromyalgia after 5 years' follow-up were consistent in different models after adjusting for different covariates (adjusted hazard ratios [aHRs]: 0.505, 0.665, and 0.601). Also, significantly lower risks of incident fibromyalgia were identified across different follow-up periods, namely, 1 day to 1 year (HR: 0.464; 95% CI, 0.386-0.559), 1 day to 3 years (HR: 0.553; 95% CI, 0.494-0.618), 1 day to 5 years (HR: 0.601; 95% CI, 0.549-0.658), and 1 day to 7 years (HR: 0.636; 95% CI, 0.587-0.690).

CONCLUSIONS

This study demonstrates that HPV vaccination significantly decreases the risk of developing incident fibromyalgia across different follow-up periods and subgroups. Our study suggests that HPV vaccination may potentially reduce the risk of developing fibromyalgia in female patients, which needs validation through studies of the mechanisms involved.

Identification of subgroups in the Danish population for targeted human papillomavirus vaccination efforts

BACKGROUND

In the Danish childhood vaccination program, the human papillomavirus (HPV) vaccination coverage is lower than for other vaccines. To tailor a targeted HPV vaccination effort, we aimed to identify girls in Denmark with lower first dose HPV vaccination coverage than girls in general.

METHODS

A population-based retrospective cohort study was performed of girls born in 2001-2004, residing in Denmark in September 2019 (N = 128,351). Data from the Danish Vaccination Register was linked to sociodemographic data from the Danish Civil Registration System and Statistics Denmark. Cox's proportional hazard regression models were used to compare vaccination uptake rates between subgroups of girls.

RESULTS

HPV vaccination coverage at 14 years of age varied widely by municipality (53.4-80.6%). Girls living with neither of their parents had a lower chance of being vaccinated compared to girls living with both their parents (HR 0.43; 95% CI 0.41-0.46), likewise for girls attending special need education compared with girls attending public schools (HR 0.50; 95% CI 0.42-0.59). The vaccination uptake among immigrants was lower compared to Danish-born girls (HR 0.51; 95% CI 0.49-0.54), especially among immigrant girls whose parents had not passed any Danish exams. Finally, girls who were DTaP-IPV revaccinated had a 50% greater chance of being HPV vaccinated compared to girls who were not (HR 1.61; 95% CI 1.58-1.64).

CONCLUSION

To increase the HPV vaccination uptake, we recommend vaccination efforts targeting girls living without any of their parents, girls attending special need education, immigrants, and girls who are not DTaP-IPV revaccinated. When targeting immigrants, the effort should focus on disseminating sufficient and understandable information about the Danish childhood vaccination program to the parents.

Post-HPV-Vaccination Mast Cell Activation Syndrome: Possible Vaccine-Triggered Escalation of Undiagnosed Pre-Existing Mast Cell Disease?

For nearly a decade, case reports and series have emerged regarding dysautonomias-particularly postural orthostatic tachycardia syndrome (POTS)-presenting soon after vaccination against human papilloma virus (HPV). We too have observed a number of such cases (all following vaccination with the Gardasil product), and have found several to have detectable mast cell activation syndrome (MCAS) as well as histories suggesting that MCAS was likely present long before vaccination. We detail 11 such cases here, posing a hypothesis that HPV vaccination (at least with the Gardasil product) may have triggered or exacerbated MCAS in teenagers previously not recognized to have it. Only recently recognized, MCAS is being increasingly appreciated as a prevalent and chronic multisystem disorder, often emerging early in life and presenting with inflammatory ± allergic phenomena following from known mast cell (MC) mediator effects. There is rising recognition, too, of associations of MCAS with central and peripheral neuropathic disorders, including autonomic disorders such as POTS. Given the recognized potential for many antigens to trigger a major and permanent escalation of baseline MC misbehavior in a given MCAS patient, we hypothesize that in our patients described herein, vaccination with Gardasil may have caused pre-existing (but not yet clinically recognized) MCAS to worsen to a clinically significantly degree, with the emergence of POTS and other issues. The recognition and management of MCAS prior to vaccinations in general may be a strategy worth investigating for reducing adverse events following HPV vaccinations and perhaps even other types of vaccinations.

Pre-vaccination vulnerability and suspected adverse events following HPV vaccination. A case-control study nested in the Danish national birth cohort

Previous studies have indicated that girls experiencing suspected adverse events (AE) following HPV vaccination were more vulnerable prior to vaccination. However, no study has previously investigated differences in vulnerability using prospectively collected self-reported measures of vulnerability. The objective of this study therefore was to describe the distribution of biological and psychosocial indicators of vulnerability in girls referred to a hospital setting due to suspected adverse events and compare it with a sample of non-referred HPV vaccinated girls. The study was conducted as a case control study based within the Danish National Birth Cohort. Cases were defined as HPV vaccinated girls referred to a hospital setting between 2015 and 2017 due to suspected adverse events (n = 80), and 5 controls were randomly selected from the remaining source population, matched to cases on age at vaccination, region of residence and year of vaccination. The final study population consisted of 480 girls. Prior exposures were based on information gathered from an 11 year follow up of the DNBC and included information on self-rated health, frequent health complaints, medication use, bullying, stressful life events and physical activity. Conditional logistic regression analysis was used to estimate the association between each exposure and referral. The percentage of individuals in the exposed category of each exposure was generally higher for cases than controls. Particularly, the odds of being referred were higher for those with low self-rated health compared to high (OR [95%-CI] 2.43 [1.07-5.5]1), those being bullied (OR 3.19 [1.17-8.73]), and those who had taken medication (OR 2.22 [1.32-3.67]). Overall, these results indicated that girls experiencing suspected AE following HPV vaccination were more vulnerable prior to vaccination.

Infections in temporal proximity to HPV vaccination and adverse effects following vaccination in Denmark: A nationwide register-based cohort study and case-crossover analysis

BACKGROUND

Public trust in the human papilloma virus (HPV) vaccination programme has been challenged by reports of potential severe adverse effects. The reported adverse symptoms were heterogeneous and overlapping with those characterised as chronic fatigue syndrome (CFS) and have been described as CFS-like symptoms. Evidence suggests that CFS is often precipitated by an infection. The aim of the study was to examine if an infection in temporal proximity to HPV vaccination is a risk factor for suspected adverse effects following HPV vaccination.

METHODS AND FINDINGS

The study was a nationwide register-based cohort study and case-crossover analysis. The study population consisted of all HPV vaccinated females living in Denmark, born between 1974 and 2006, and vaccinated between January 1, 2006 and December 31, 2017. The exposure was any infection in the period ± 1 month around time of first HPV vaccination and was defined as (1) hospital-treated infection; (2) redemption of anti-infective medication; or (3) having a rapid streptococcal test done at the general practitioner. The outcome was referral to a specialised hospital setting (5 national HPV centres opened June 1, 2015) due to suspected adverse effects following HPV vaccination. Multivariable logistic regression was used to estimate the association between infection and later HPV centre referral. The participants were 600,400 HPV-vaccinated females aged 11 to 44 years. Of these, 48,361 (9.7%) females had a hospital-treated infection, redeemed anti-infective medication, or had a rapid streptococcal test ± 1 month around time of first HPV vaccination. A total of 1,755 (0.3%) females were referred to an HPV centre. Having a hospital-treated infection in temporal proximity to vaccination was associated with significantly elevated risk of later referral to an HPV centre (odds ratio (OR) 2.75, 95% confidence interval (CI) 1.72 to 4.40; P < 0.001). Increased risk was also observed among females who redeemed anti-infective medication (OR 1.56, 95% CI 1.33 to 1.83; P < 0.001) or had a rapid streptococcal test (OR 1.45, 95% CI 1.10 to 1.93; P = 0.010). Results from a case-crossover analysis, which was performed to adjust for potential unmeasured confounding, supported the findings. A key limitation of the study is that the HPV centres did not open until June 1, 2015, which may have led to an underestimation of the risk of suspected adverse effects, but stratified analyses by year of vaccination yielded similar results.

CONCLUSIONS

Treated infection in temporal proximity to HPV vaccination is associated with increased risk for later referral with suspected adverse vaccine effects. Thus, the infection could potentially be a trigger of the CFS-like symptoms in a subset of the referred females. To our knowledge, the study is the first to investigate the role of infection in the development of suspected adverse effects after HPV vaccination and replication of these findings are needed in other studies.

Multiple cohort HPV vaccination in Zimbabwe: 2018-2019 program feasibility, awareness, and acceptability among health, education, and community stakeholders

INTRODUCTION

Zimbabwe introduced human papillomavirus (HPV) vaccine nationally in May 2018, targeting multiple cohorts (girls aged 10-14 years) through a school-based vaccination campaign. One year later, the second dose was administered to the multiple cohorts concurrently with the first dose given to a new single cohort of girls in grade 5. We conducted cross-sectional surveys among health workers, school personnel, and community members to assess feasibility of implementation, training, social mobilization, and community acceptability.

METHODS

Thirty districts were selected proportional to the volume of the HPV vaccine doses delivered in 2018; two health facilities were randomly selected within each district. One health worker, school health coordinator, village health worker, and community leader were surveyed at each selected health facility and surrounding area during January-February 2020, using standard questionnaires. Descriptive analysis was completed across groups.

RESULTS

There were 221 interviews completed. Over 60% of health workers reported having enough staff to carry out vaccination sessions in schools while maintaining routine vaccination services in health facilities. All school health coordinators felt the HPV vaccine should be delivered in schools in the future. Knowledge of the correct target cohort eligibility decreased from 91% in 2018 to 50% in 2020 among health workers. Understanding of HPV infection and use of HPV vaccine for cervical cancer prevention was above 90% for all respondents. Forty-two percent of respondents reported hearing rumors about the HPV vaccine, primarily regarding infertility and safety.

CONCLUSIONS

Findings demonstrate the presence of highly knowledgeable staff at health facilities and schools, strong community acceptance, and a school-based HPV program considered feasible to implement in Zimbabwe. However, misunderstandings regarding target eligibility and rumors persist, which can impact vaccine uptake and coverage. Continued social mobilization efforts to maintain community demand and training on eligibility were recommended. Integration, partnerships, and resource mobilization are also needed to ensure program sustainability.

Real-World Effectiveness of Human Papillomavirus Vaccination Against Cervical Cancer

BACKGROUND

The primary goal of human papillomavirus (HPV) vaccination is to reduce morbidity and mortality from HPV-associated disease, especially cervical cancer. We determined the real-world effectiveness of HPV vaccination against cervical cancer.

METHODS

The study included women aged 17-30 years living in Denmark October 2006-December 2019. From nationwide registries, information on HPV vaccination and cervical cancer diagnoses were retrieved. Incidence rate ratios (IRRs) with 95% confidence intervals (CIs) for cervical cancer according to vaccination status were estimated using Poisson regression with HPV vaccination treated as a time-varying variable and stratified by age at vaccination. We adjusted for attained age, education, and ethnicity. To address the effect of prevalent disease, different buffer periods were used, with 1-year buffer period as primary analysis.

RESULTS

The cohort comprised 867 689 women. At baseline, 36.3% were vaccinated at age 16 years and younger, and during follow-up, 19.3% and 2.3% were vaccinated at ages 17-19 years and 20-30 years, respectively. For women vaccinated at ages 16 years and younger or 17-19 years, the IRRs of cervical cancer were 0.14 (95% CI = 0.04 to 0.53) and 0.32 (95% CI = 0.08 to 1.28), respectively, compared with unvaccinated women. In women aged 20-30 years at vaccination, the incidence rate was higher than among unvaccinated women (IRR = 1.19, 95% CI = 0.80 to 1.79) but slightly decreased with increasing buffer period (IRR = 0.85, 95% CI = 0.55 to 1.32, with 4-year buffer period).

CONCLUSION

HPV vaccine effectiveness against cervical cancer at the population level is high among girls vaccinated younger than age 20 years. The lack of immediate effect in women vaccinated at age 20-30 years points to the importance of early age at vaccination.

Human papillomavirus (HPV) vaccine and autonomic disorders: a position statement from the American Autonomic Society

INTRODUCTION

Human papillomavirus (HPV) vaccination has been anecdotally connected to development of dysautonomia, chronic fatigue, complex regional pain syndrome and postural tachycardia syndrome.

OBJECTIVES

To critically evaluate a potential connection between HPV vaccination and above noted conditions.

METHODS

We reviewed the literature containing the biology of the virus, pathophysiology of infection, epidemiology of associated cancers, indications of HPV vaccination, safety surveillance data and published reports linking HPV vaccination to autonomic disorders.

RESULTS

At this time the American Autonomic Society finds that there are no data to support a causal relationship between HPV vaccination and CRPS, chronic fatigue, POTS or other forms of dysautonomia.

CONCLUSIONS

Certain conditions are prevalent in the same patient populations that are vaccinated with the HPV vaccine (peri-pubertal males and females). This association, however, is insufficient proof of causality.

General Practitioner Attendance in Proximity to HPV Vaccination: A Nationwide, Register-Based, Matched Case-Control Study

Aim

This study aimed to describe and compare general practitioner (GP) attendance patterns in the years surrounding HPV-vaccination among cases suspected to experience adverse events and their matched controls in order to determine if a potential larger change in GP attendance among cases was observed in temporal relation to vaccination.

Methods

Register-based, matched case-control study. Cases were defined as women referred to specialized hospital settings (HPV-centers) for suspected adverse event between June 1st 2015 and December 31st 2015 (n=1458). Information on referral was obtained from the HPV-centers directly. Each case was matched with five controls on age at vaccination, region, time of first vaccine registration and total number of doses, resulting in a total study population of 8670 girls and women. Negative binomial regression analyses were used (i) to estimate mean yearly GP contacts among cases and controls, and (ii) to further investigate the relative difference in change in GP attendance following vaccination between cases and controls.

Results

Overall, cases displayed higher GP attendance than controls from five years before vaccination up until five years after. Compared to controls, cases increased their GP attendance more in the years following HPV vaccination, corresponding to a 40% increase in the incidence rate ratios (IRR) from before to after vaccination (ratio-IRR = 1.40 [1.36; 1.44]). The change occurred in close proximity to vaccination, and the pattern was the same independently of the year of vaccination. However, for the later vaccination years cases displayed an additional increase in their GP attendance around time of extensive media attention.

Conclusion

Girls and women being referred for suspected adverse events after HPV-vaccination changed their GP attendance pattern in close proximity to their first HPV-vaccination and not solely in temporal linkage to the onset of public debate.

Association between quadrivalent human papillomavirus vaccination and selected syndromes with autonomic dysfunction in Danish females: population based, self-controlled, case series analysis

OBJECTIVE

To evaluate the association between quadrivalent human papillomavirus vaccination and syndromes with autonomic dysfunction, such as chronic fatigue syndrome, complex regional pain syndrome, and postural orthostatic tachycardia syndrome.

DESIGN

Population-based self-controlled case series.

SETTING

Information on human papillomavirus vaccinations and selected syndromes with autonomic dysfunction (chronic fatigue syndrome, complex regional pain syndrome, and postural orthostatic tachycardia syndrome) identified using ICD-10 (international classification of diseases, revision 10) diagnostic codes from Danish nationwide registers.

PARTICIPANTS

869 patients with autonomic dysfunction syndromes from a cohort of 1 375 737 Danish born female participants aged 10 to 44 years during 2007-16.

MAIN OUTCOME MEASURES

Self-controlled case series rate ratios (95% confidence intervals) of the composite outcome of chronic fatigue syndrome, complex regional pain syndrome, and postural orthostatic tachycardia syndrome, adjusted for age and season, comparing female participants vaccinated and unvaccinated with the quadrivalent human papillomavirus vaccine. Chronic fatigue syndrome, complex regional pain syndrome, and postural orthostatic tachycardia syndrome were also considered separately in secondary analyses.

RESULTS

During 10 581 902 person years of follow-up, 869 female participants with syndromes of autonomic dysfunction (136 with chronic fatigue syndrome, 535 with complex regional pain syndrome, and 198 with postural orthostatic tachycardia syndrome) were identified. Quadrivalent human papillomavirus vaccination did not statistically significantly increase the rate of a composite outcome of all syndromes with autonomic dysfunction in a 365 day risk period following vaccination (rate ratio 0.99, 95% confidence interval 0.74 to 1.32) or the rate of any individual syndrome in the risk period (chronic fatigue syndrome (0.38, 0.13 to 1.09), complex regional pain syndrome (1.31, 0.91 to 1.90), or postural orthostatic tachycardia syndrome (0.86, 0.48 to 1.54)).

CONCLUSIONS

When vaccination is introduced, adverse events could occur in close temporal relation to the vaccine purely by chance. These results do not support a causal association between quadrivalent human papillomavirus vaccination and chronic fatigue syndrome, complex regional pain syndrome, or postural orthostatic tachycardia syndrome, either individually or as a composite outcome. An increased risk of up to 32% cannot be formally excluded, but the statistical power of the study suggests that a larger increase in the rate of any syndrome associated with vaccination is unlikely.

Human Papillomavirus Vaccination and Physical and Mental Health Complaints Among Female Students in Secondary Education Institutions in Denmark

BACKGROUND

Previous studies have not explored the effect of HPV vaccination on health status at a longer time interval. Similarly, self-reported physical and mental health in recipients of the HPV vaccine has not been studied.

OBJECTIVE

To evaluate whether HPV vaccination was associated with physical and mental health complaints among girls in secondary education institutions.

DESIGN

Prospective cohort study.

PARTICIPANTS

This study used data from girls aged 15-20 years who participated in the Danish National Youth Study (DNYS) 2014. Data on HPV vaccination was retrieved from the Danish Vaccination Register.

MAIN MEASURES

Participants were asked whether they had experienced headaches, stomachache, neck pain, menstrual cramps, sore throat, sadness, irritation, nervousness and sleep problems in the past 6 months.

KEY RESULTS

Of 41,333 girls, 39,145 (94.7%) received at least one dose of HPV vaccine. The most prevalent health complaint among the vaccinated and not vaccinated females was "been irritable" (88.2% and 88.4%, respectively). The lowest proportion of health complaints was stomachache (49.6% in vaccinated and in 50.4% in unvaccinated girls). Regression model, adjusted for socio-demographic characteristics and health behavior, showed that HPV vaccination was associated with a lower likelihood of reporting sore throat (odd ratio [OR] 0.86, 95% confidence interval [CI] 0.78-0.95) and being sad (OR 0.86, 95%CI 0.76-0.97). Similar results were observed when HPV vaccination status was analyzed according to the number of doses received.

CONCLUSION

We conclude that HPV vaccination was not associated with physical and mental health complaints among girls in secondary education institutions in Denmark after a median of 5.3 years since HPV vaccination.

Are unexplained adverse health events following HPV vaccination associated with infectious mononucleosis? - A Danish nationwide matched case-control study

BACKGROUND

In Denmark, the acceptance of the HPV vaccination program has been threatened by reports of suspected adverse events. Epstein Barr Virus (EBV) infection is associated with symptoms of long-lasting tiredness and may be misinterpreted as HPV vaccine adverse events. The main aim of this study was to examine if EBV infection around time of HPV vaccination was a risk factor for later suspected vaccine adverse events.

METHODS

The study was a nationwide register-based matched case-control study. Cases were females vaccinated against HPV in the period 2011 throughout 2017 with suspected adverse events. For each case, five HPV vaccinated females without suspected adverse events were selected. Information about EBV infection was obtained from the Danish Microbiology Database and assessed for three time periods: (1) before first HPV vaccination, (2) around time of HPV vaccination, and (3) any time during the study period 2010-2017. Multiple logistic regression was used to estimate the association between EBV and suspected adverse events.

RESULTS

We identified 1217 cases, matched to 6085 controls. A higher proportion of cases (38; 3.1%) than controls (31; 0.5%) were tested for EBV around time of HPV vaccination and cases had elevated odds for testing both EBV positive (OR 4.52, 95% CI 2.68-7.63) and EBV negative (OR 20.99, 95% CI 5.81-75.79). Only five females were classified with acute/recent EVB infection in this period.

CONCLUSION

Misinterpretation of EBV infection late symptoms is not a leading explanation for Danish females experiencing suspected adverse events after HPV vaccination. Although EBV cannot be excluded as an explanatory factor for a very small proportion of suspected adverse events, the findings are more likely explained by protopathic bias, i.e. the fact that a larger proportion of females suspecting adverse events are tested for EBV.

Hazard of complex regional pain syndrome following human papillomavirus vaccination among adolescent girls in the United States: a case-cohort analysis of insurance claims data

Objectives: Complex regional pain syndrome (CRPS) cases have followed human papillomavirus (HPV) vaccination, but no causal link has been established.Methods: Using insurance claims, the authors observed unvaccinated 11-year-old girls for CRPS diagnoses. The authors used time-dependent Cox regression to identify health-related CRPS predictors using diagnosis codes. Next, the authors identified HPV vaccinations using procedural codes. HPV vaccination and CRPS predictors were considered time-dependent covariates to estimated adjusted hazard ratios (HR) and 95% confidence intervals (CI) for CRPS, 30, 90, and 180-days post-vaccination.Results: 1,232,572 girls received 563 unique CRPS diagnoses. In a 10% sub-cohort of 123,981 girls accounting for potential confounders and predisposing risk factors (i.e. injury, infection, mental illness, primary care use), CRPS hazard was not significantly elevated 30 days (HR: 0.90, 95% CI: 0.46, 1.73), 90 days (HR: 1.17, 95% CI: 0.83, 1.65), or 180-days post-vaccination (HR: 1.11, 95% CI: 0.83, 1.47).Conclusion: The results support the safety and continued administration of HPV vaccines to adolescents.

Human papillomavirus (HPV) vaccine and autonomic disorders: a position statement from the American Autonomic Society

INTRODUCTION

Human papillomavirus (HPV) vaccination has been anecdotally connected to the development of dysautonomia, chronic fatigue, complex regional pain syndrome and postural tachycardia syndrome.

OBJECTIVES

To critically evaluate a potential connection between HPV vaccination and the above-noted conditions.

METHODS

We reviewed the literature containing the biology of the virus, pathophysiology of infection, epidemiology of associated cancers, indications of HPV vaccination, safety surveillance data and published reports linking HPV vaccination to autonomic disorders.

RESULTS

At this time, the American Autonomic Society finds that there are no data to support a causal relationship between HPV vaccination and CRPS, chronic fatigue, and postural tachycardia syndrome to other forms of dysautonomia.

CONCLUSION

Certain conditions are prevalent in the same populations that are vaccinated with the HPV vaccine (peri-pubertal males and females). This association, however, is an insufficient proof of causality.

Autonomic dysfunction and HPV immunization: an overview

This article reviews the case series reported from several countries describing patients with suspected severe side effects to the HPV vaccines. The described symptom clusters are remarkably similar and include disabling fatigue, headache, widespread pain, fainting, gastrointestinal dysmotility, limb weakness, memory impairment episodes of altered awareness, and abnormal movements. This constellation of symptoms and signs has been labeled with different diagnoses such as complex regional pain syndrome (CRPS), postural orthostatic tachycardia syndrome (POTS), small fiber neuropathy (SFN), myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), or fibromyalgia. It is known that autoimmunity and autoantibodies are present in a subset of patients with CRPS, POTS, SFN, ME/CFS, and fibromyalgia. This article proposes that vaccine-triggered, immune-mediated autonomic dysfunction could lead to the development of de novo post-HPV vaccination syndrome possibly in genetically susceptible individuals. Being cognizant that a temporal relationship between vaccination and symptom onset does not necessarily equate to causality, mounting evidence of case series calls for well-designed case-control studies to determine the prevalence and possible causation between these symptom clusters and HPV vaccines. Since personalized medicine is gaining momentum, the use of adversomics and pharmacogenetics may eventually help identify individuals who are predisposed to HPV vaccine adverse events.

On the contextual nature of vaccine safety monitoring: Adverse events reporting after HPV-vaccination in Denmark, 2015

BACKGROUND

In 2013-15, Denmark experienced an increase in reported suspected adverse events following vaccination (AEFI) against human papilloma virus (HPV). Dedicated centres ("One Access") were established in order to standardize management of patients who experienced medically unexplained physical symptoms after HPV vaccination. Since One Access was targeted patients with suspected AEFI after HPV vaccination, we used this opportunity to estimate completeness in AEFI reporting to the Danish Medicines Agency (DMA), and explore the topic of AEFI reporting from the perspective of physicians working at the centres to better understand health professionals' reporting behaviour.

METHODS

The study consisted of a quantitative and a qualitative part. In the quantitative analysis, we used the Danish civil registry number to merge a line-list of all One Access patients referred in 2015 with total number of patients who had reported suspected serious AEFI following HPV vaccination to the DMA in the years 2009-2015. We conducted four semi-structured interviews with doctors representing three out of five regions. The Theoretical Domains Framework together with empirical data from two clinical fieldtrips guided the formation of the qualitative study.

RESULTS

Among 1577 One Access patients, only 404 (26%) were reported to the DMA. We found significant regional differences in reporting completeness (p < 0.001) and differences between regions when looking at reporters' backgrounds (healthcare professionals vs non-professionals; p = 0.004). We identified several factors of importance for reporting behaviour amongst physicians, mainly under the domains of Knowledge, Motivation & Goals, and Environmental Context.

CONCLUSIONS

Despite an official aim of homogenous case management, reporting of suspected AEFI was incomplete with large regional differences. The qualitative study corroborated that reporting behaviour was contextual. This observation represents an important caveat in interpreting data from AEFI reporting, in particular when these data are used for research or policymaking.

Hospital contacts and diagnoses five years prior to HPV vaccination among females referred for suspected adverse vaccine effects: A Danish nationwide case-control study

BACKGROUND

High health care utilization before Human Papilloma Virus (HPV) vaccination might be associated with increased risk of suspected adverse effects (AE's) after vaccination. We investigated the association between hospital contacts and diagnoses before HPV vaccination and risk of later referral to a specialized hospital setting (HPV center) for suspected AE's.

METHODS

The study was a Danish register-based matched case-control study. Cases were females referred to an HPV center. Five controls per case were randomly selected in the source population of HPV vaccinated females. Information on hospital contacts and diagnoses was obtained from the Danish National Patient Registry. Conditional logistic regression analyses were used to investigate the association between having one or more diagnoses in each specific International Classification of Diseases 10th version (ICD-10) chapter five years before the HPV vaccination and subsequent referral to an HPV center.

RESULTS

We identified 1496 cases and 7480 controls. In total, 80% of the cases versus 65% of the controls had at least one hospital contact prior to HPV vaccination (Prevalence Proportion Ratio - PPR: 1.24 (95% Confidence Interval - CI: 1.21-1.27)), with 24% vs 12% (PPR: 1.97 (95% CI: 1.76-2.19)) having six or more contacts. Cases were more likely to have had a diagnosis in 15 out of 19 ICD-10 chapters before the vaccination, with ORs larger than 1.8 for infectious diseases, psychiatric diseases, diseases of the nervous, circulatory, digestive and musculoskeletal system, unspecific symptoms and unspecific contacts.

CONCLUSION

Pre-vaccination morbidity and health care utilization seem to play a role in the path leading to suspected AE's after HPV vaccination. Since many of the diagnoses that were particularly increased before vaccination in referred females are overlapping with the most frequent symptoms reported, we cannot exclude that for some of the females, the suspected AE's might have been existing already before the vaccination.

Relationship Between Media Coverage and Measles-Mumps-Rubella (MMR) Vaccination Uptake in Denmark: Retrospective Study

BACKGROUND

Understanding the influence of media coverage upon vaccination activity is valuable when designing outreach campaigns to increase vaccination uptake.

OBJECTIVE

To study the relationship between media coverage and vaccination activity of the measles-mumps-rubella (MMR) vaccine in Denmark.

METHODS

We retrieved data on media coverage (1622 articles), vaccination activity (2 million individual registrations), and incidence of measles for the period 1997-2014. All 1622 news media articles were annotated as being provaccination, antivaccination, or neutral. Seasonal and serial dependencies were removed from the data, after which cross-correlations were analyzed to determine the relationship between the different signals.

RESULTS

Most (65%) of the anti-vaccination media coverage was observed in the period 1997-2004, immediately before and following the 1998 publication of the falsely claimed link between autism and the MMR vaccine. There was a statistically significant positive correlation between the first MMR vaccine (targeting children aged 15 months) and provaccination media coverage (r=.49, P=.004) in the period 1998-2004. In this period the first MMR vaccine and neutral media coverage also correlated (r=.45, P=.003). However, looking at the whole period, 1997-2014, we found no significant correlations between vaccination activity and media coverage.

CONCLUSIONS

Following the falsely claimed link between autism and the MMR vaccine, provaccination and neutral media coverage correlated with vaccination activity. This correlation was only observed during a period of controversy which indicates that the population is more susceptible to media influence when presented with diverging opinions. Additionally, our findings suggest that the influence of media is stronger on parents when they are deciding on the first vaccine of their children, than on the subsequent vaccine because correlations were only found for the first MMR vaccine.

Examining determinants for reporting suspected adverse events following HPV vaccination in Denmark

HPV vaccination has been offered to 12-year-old girls as part of the Danish Childhood Vaccination Programme since 2009. From 2013, an increasing number of suspected severe adverse events (AE) without a documented causal link to the vaccine was observed, resulting in public concerns about vaccine safety and a decline in uptake. This study aimed at describing the group of females reporting AE and comparing them to vaccinated peers not reporting AE. A questionnaire focusing on demographics, lifestyle, and health-related issues was distributed to 251 female cases who had reported severe AE and 1,003 female controls randomly selected from the population-based Danish Vaccination Registry. All had been HPV-vaccinated. There were no significant differences on measures of self-reported psychiatric or somatic conditions before vaccination. More cases reported being physically very active prior to first HPV vaccination (OR 4.2) whereas fewer cases than controls sometimes (OR 0.31) or often/always (OR 0.36) felt sad. This is unexpected because two recent Danish registry-based case-control studies concluded that females reporting severe AE were more likely to consult a psychologist/psychiatrist and to have pre-existing psychiatric conditions before first HPV vaccination. One of these studies also showed that cases had increased health-care seeking regarding a number of somatic conditions prior to first vaccination. Our study adds value when seeking to understand the lifeworld of the affected females and their interpretations of their everyday lives pre- and post-HPV vaccination.

The association of adverse events with bivalent human papilloma virus vaccination: A nationwide register-based cohort study in Finland

BACKGROUND

A bivalent HPV vaccine (Cervarix®; HPV2, GlaxoSmithKline) was introduced into the Finnish national vaccination programme (NVP) in November 2013 for girls aged 11-13 years with a catch-up for 14-15 year-olds. We evaluated the association between HPV2 and selected autoimmune diseases and clinical syndromes by conducting a nation-wide retrospective register-based cohort study.

METHODS

First life-time occurrences of the relevant ICD-10 codes in girls aged 11-15 years between Nov-2013 and Dec-2016 were obtained from the national hospital discharge register. Population denominators were obtained from the Population Information System and vaccination records from the National Vaccination Register. Registers were linked using unique personal identity codes. Association between HPV2 and 38 selected outcomes were studied using Cox regression, with age as the main time-scale and the first vaccination dose as the time-dependent exposure. The hazard ratios (HR) with 95%CI were assessed according to the time since exposure (entire follow-up, 0-180/181-365/>365 days).

RESULTS

Of 240 605 girls eligible for HPV2 vaccination, 134 615 (56%) were vaccinated. After adjustment for geographical area (6 hospital districts), country of origin (Finnish-born/not) and number of hospital contacts from 9 through 10 years of age, HRs ranged from 0.34 (95%CI 0.11-1.05) to 8.37 (95%CI 0.85-82.54) and HPV2 vaccination was not statistically significantly associated with a higher risk of any outcome during the entire follow-up.

CONCLUSIONS

This study found no significantly increased risk for the selected outcomes after the HPV vaccination in girls 11-15 years of age. These results provide valid evidence to counterbalance public scepticism, fears of adverse events and possible opposition to HPV vaccination and consequently can contribute to increase HPV vaccination coverage in Finland as well as elsewhere.

Danish method study on cervical screening in women offered HPV vaccination as girls (Trial23): a study protocol

INTRODUCTION

The first birth cohorts of women offered human papillomavirus (HPV) vaccination as girls are now entering cervical screening. However, there is no international consensus on how to screen HPV vaccinated women. These women are better protected against cervical cancer and could therefore be offered less intensive screening. Primary HPV testing is more sensitive than cytology, allowing for a longer screening interval. The aim of Trial23 is to investigate if primary HPV testing with cytology triage of HPV positive samples is a reasonable screening scheme for women offered HPV vaccination as girls.

METHODS

Trial23 is a method study embedded in the existing cervical screening programme in four out of five Danish regions. Without affecting the screening programme, women born in 1994 are randomised to present screening with liquid-based cytology every third year (present programme arm) or present screening plus an HPV test (HPV arm). The study started 1 February 2017 and will run over three screening rounds corresponding to 7-8 years.

ANALYSES

The primary endpoint is cervical intraepithelial neoplasia grade 3 or above. The trial is undertaken as a non-inferiority study including intention-to-treat and per-protocol analyses. The potential effect of primary HPV screening with a 6-year interval will be calculated from the observed data.

ETHICS AND DISSEMINATION

The study protocol has been submitted to the ethical committee and deemed a method study. All women are screened according to routine guidelines. The study will contribute new evidence on the future screening of HPV vaccinated birth cohorts of women. All results will be published in open-access journal.

TRIAL REGISTRATION

NCT03049553; Pre-results.

Prophylactic vaccination against human papillomaviruses to prevent cervical cancer and its precursors

BACKGROUND

Persistent infection with high-risk human papillomaviruses (hrHPV) types is causally linked with the development of cervical precancer and cancer. HPV types 16 and 18 cause approximately 70% of cervical cancers worldwide.

OBJECTIVES

To evaluate the harms and protection of prophylactic human papillomaviruses (HPV) vaccines against cervical precancer and HPV16/18 infection in adolescent girls and women.

SEARCH METHODS

We searched MEDLINE, Cochrane Central Register of Controlled Trials (CENTRAL) and Embase (June 2017) for reports on effects from trials. We searched trial registries and company results' registers to identify unpublished data for mortality and serious adverse events.

SELECTION CRITERIA

Randomised controlled trials comparing efficacy and safety in females offered HPV vaccines with placebo (vaccine adjuvants or another control vaccine).

DATA COLLECTION AND ANALYSIS

We used Cochrane methodology and GRADE to rate the certainty of evidence for protection against cervical precancer (cervical intraepithelial neoplasia grade 2 and above [CIN2+], CIN grade 3 and above [CIN3+], and adenocarcinoma-in-situ [AIS]), and for harms. We distinguished between the effects of vaccines by participants' baseline HPV DNA status. The outcomes were precancer associated with vaccine HPV types and precancer irrespective of HPV type. Results are presented as risks in control and vaccination groups and risk ratios (RR) with 95% confidence intervals in brackets.

MAIN RESULTS

We included 26 trials (73,428 participants). Ten trials, with follow-up of 1.3 to 8 years, addressed protection against CIN/AIS. Vaccine safety was evaluated over a period of 6 months to 7 years in 23 studies. Studies were not large enough or of sufficient duration to evaluate cervical cancer outcomes. All but one of the trials was funded by the vaccine manufacturers. We judged most included trials to be at low risk of bias. Studies involved monovalent (N = 1), bivalent (N = 18), and quadrivalent vaccines (N = 7). Most women were under 26 years of age. Three trials recruited women aged 25 and over. We summarize the effects of vaccines in participants who had at least one immunisation.Efficacy endpoints by initial HPV DNA statushrHPV negativeHPV vaccines reduce CIN2+, CIN3+, AIS associated with HPV16/18 compared with placebo in adolescent girls and women aged 15 to 26. There is high-certainty evidence that vaccines lower CIN2+ from 164 to 2/10,000 (RR 0.01 (0 to 0.05)) and CIN3+ from 70 to 0/10,000 (RR 0.01 (0.00 to 0.10). There is moderate-certainty evidence that vaccines reduce the risk of AIS from 9 to 0/10,000 (RR 0.10 (0.01 to 0.82).HPV vaccines reduce the risk of any CIN2+ from 287 to 106/10,000 (RR 0.37 (0.25 to 0.55), high certainty) and probably reduce any AIS lesions from 10 to 0/10,000 (RR 0.1 (0.01 to 0.76), moderate certainty). The size of reduction in CIN3+ with vaccines differed between bivalent and quadrivalent vaccines (bivalent: RR 0.08 (0.03 to 0.23), high certainty; quadrivalent: RR 0.54 (0.36 to 0.82), moderate certainty). Data in older women were not available for this comparison.HPV16/18 negativeIn those aged 15 to 26 years, vaccines reduce CIN2+ associated with HPV16/18 from 113 to 6 /10,000 (RR 0.05 (0.03 to 0.10). In women 24 years or older the absolute and relative reduction in the risk of these lesions is smaller (from 45 to 14/10,000, (RR 0.30 (0.11 to 0.81), moderate certainty). HPV vaccines reduce the risk of CIN3+ and AIS associated with HPV16/18 in younger women (RR 0.05 (0.02 to 0.14), high certainty and RR 0.09 (0.01 to 0.72), moderate certainty, respectively). No trials in older women have measured these outcomes.Vaccines reduce any CIN2+ from 231 to 95/10,000, (RR 0.41 (0.32 to 0.52)) in younger women. No data are reported for more severe lesions.Regardless of HPV DNA statusIn younger women HPV vaccines reduce the risk of CIN2+ associated with HPV16/18 from 341 to 157/10,000 (RR 0.46 (0.37 to 0.57), high certainty). Similar reductions in risk were observed for CIN3+ associated with HPV16/18 (high certainty). The number of women with AIS associated with HPV16/18 is reduced from 14 to 5/10,000 with HPV vaccines (high certainty).HPV vaccines reduce any CIN2+ from 559 to 391/10,000 (RR 0.70 (0.58 to 0.85, high certainty) and any AIS from 17 to 5/10,000 (RR 0.32 (0.15 to 0.67), high certainty). The reduction in any CIN3+ differed by vaccine type (bivalent vaccine: RR 0.55 (0.43 to 0.71) and quadrivalent vaccine: RR 0.81 (0.69 to 0.96)).In women vaccinated at 24 to 45 years of age, there is moderate-certainty evidence that the risks of CIN2+ associated with HPV16/18 and any CIN2+ are similar between vaccinated and unvaccinated women (RR 0.74 (0.52 to 1.05) and RR 1.04 (0.83 to 1.30) respectively). No data are reported in this age group for CIN3+ or AIS.Adverse effectsThe risk of serious adverse events is similar between control and HPV vaccines in women of all ages (669 versus 656/10,000, RR 0.98 (0.92 to 1.05), high certainty). Mortality was 11/10,000 in control groups compared with 14/10,000 (9 to 22) with HPV vaccine (RR 1.29 [0.85 to 1.98]; low certainty). The number of deaths was low overall but there is a higher number of deaths in older women. No pattern in the cause or timing of death has been established.Pregnancy outcomesAmong those who became pregnant during the studies, we did not find an increased risk of miscarriage (1618 versus 1424/10,000, RR 0.88 (0.68 to 1.14), high certainty) or termination (931 versus 838/10,000 RR 0.90 (0.80 to 1.02), high certainty). The effects on congenital abnormalities and stillbirths are uncertain (RR 1.22 (0.88 to 1.69), moderate certainty and (RR 1.12 (0.68 to 1.83), moderate certainty, respectively).

AUTHORS' CONCLUSIONS

There is high-certainty evidence that HPV vaccines protect against cervical precancer in adolescent girls and young women aged 15 to 26. The effect is higher for lesions associated with HPV16/18 than for lesions irrespective of HPV type. The effect is greater in those who are negative for hrHPV or HPV16/18 DNA at enrolment than those unselected for HPV DNA status. There is moderate-certainty evidence that HPV vaccines reduce CIN2+ in older women who are HPV16/18 negative, but not when they are unselected by HPV DNA status.We did not find an increased risk of serious adverse effects. Although the number of deaths is low overall, there were more deaths among women older than 25 years who received the vaccine. The deaths reported in the studies have been judged not to be related to the vaccine. Increased risk of adverse pregnancy outcomes after HPV vaccination cannot be excluded, although the risk of miscarriage and termination are similar between trial arms. Long-term of follow-up is needed to monitor the impact on cervical cancer, occurrence of rare harms and pregnancy outcomes.

Reports of Postural Orthostatic Tachycardia Syndrome After Human Papillomavirus Vaccination in the Vaccine Adverse Event Reporting System

PURPOSE

Human papillomavirus (HPV) vaccination prevents infections with HPV strains that cause certain cancers. Reports of postural orthostatic tachycardia syndrome (POTS) following HPV vaccination have raised safety concerns. We reviewed POTS reports submitted to the Vaccine Adverse Event Reporting System (VAERS).

METHODS

We searched the VAERS database for reports of POTS following any type of HPV vaccination (bivalent, quadrivalent, or nonavalent) from June 2006 to August 2015. We reviewed reports and applied established POTS diagnostic criteria. We calculated unadjusted POTS case reporting rates based on HPV vaccine doses distributed and conducted empirical Bayesian data mining to screen for disproportional reporting of POTS following HPV vaccination.

RESULTS

Among 40,735 VAERS reports following HPV vaccination, we identified 29 POTS reports that fully met diagnostic criteria. Of these, 27 (93.1%) were in females and mean age was 14 years (range 12-32). Median time from vaccination to start of symptoms was 43 days (range 0-407); most (18, 75.0%) had onset between 0 and 90 days. Symptoms frequently reported concomitantly included headache (22, 75.9%) and dizziness (21, 72.4%). Twenty (68.9%) reports documented a history of pre-existing medical conditions, of which chronic fatigue (5, 17.2%), asthma (4, 13.8%), and chronic headache (3, 10.3%) were most common. Approximately one POTS case is reported for every 6.5 million HPV vaccine doses distributed in the United States. No empirical Bayesian data mining safety signals for POTS and HPV vaccination were detected.

CONCLUSIONS

POTS is rarely reported following HPV vaccination. Our review did not detect any unusual or unexpected reporting patterns that would suggest a safety problem.

The Eating Motivation Survey: results from the USA, India and Germany

OBJECTIVE

Research has shown that there is a large variety of different motives underlying why people eat what they eat, which can be assessed with The Eating Motivation Survey (TEMS). The present study investigates the consistency and measurement invariance of the fifteen basic motives included in TEMS in countries with greatly differing eating environments.

DESIGN

The fifteen-factor structure of TEMS (brief version: forty-six items) was tested in confirmatory factor analyses.

SETTING

An online survey was conducted.

SUBJECTS

US-American, Indian and German adults (total N 749) took part.

RESULTS

Despite the complexity of the model, fit indices indicated a reasonable model fit (for the total sample: χ 2/df=4·03; standardized root-mean-squared residual (SRMR)=0·063; root-mean-square error of approximation (RMSEA)=0·064 (95 % CI 0·062, 0·066)). Only the comparative fit index (CFI) was below the recommended threshold (for the total sample: CFI=0·84). Altogether, 181 out of 184 item loadings were above the recommended threshold of 0·30. Furthermore, the factorial structure of TEMS was invariant across countries with respect to factor configuration and factor loadings (configural v. metric invariance model: ΔCFI=0·009; ΔRMSEA=0·001; ΔSRMR=0·001). Moreover, forty-three out of forty-six items showed invariant intercepts across countries.

CONCLUSIONS

The fifteen-factor structure of TEMS was, in general, confirmed across countries despite marked differences in eating environments. Moreover, latent means of fourteen out of fifteen motive factors can be compared across countries in future studies. This is a first step towards determining generalizability of the fifteen basic eating motives of TEMS across eating environments.

Psychiatric conditions and general practitioner attendance prior to HPV vaccination and the risk of referral to a specialized hospital setting because of suspected adverse events following HPV vaccination: a register-based, matched case-control study

AIM

No association between human papilloma virus (HPV) vaccination and numerous diseases has been found. Still, a large number of Danish women are reporting suspected adverse events. Other factors may play a role, and the aim of this study is to examine the association between psychiatric conditions, general practitioner (GP) attendance and indicators of psychological symptoms prior to HPV vaccination and the risk of referral to an HPV center following vaccination.

STUDY DESIGN AND SETTING

Register-based, matched case-control study. Cases were identified from five Danish, regional HPV centers, and health data for cases and controls were obtained from national registries.

PARTICIPANTS

Cases were defined as women referred to an HPV center between January 1, 2015 and December 31, 2015 (n=1,496). Each case was matched with five controls on age, region and time of first vaccine registration. The total study population consisted of 8,976 women.

RESULTS

Overall, women above 18 years who had been referred to an HPV center were more likely to have used psychiatric medication (odds ratio [OR]: 1.88 [95% CI 1.48-2.40]) or to have been hospitalized because of a psychiatric disorder within 5 years prior to the first vaccine registration (OR: 2.13 [95% CI 1.59-2.86]). Specifically, referred women were more likely to have used antipsychotics, antidepressants, attention deficit hyperactivity disorder (ADHD) medication or anxiolytics, and to have been hospitalized for affective disorders or anxiety, but not to have been hospitalized for schizoid, ADHD or eating disorders. In addition, they were more likely to have had talk therapy or psychometric test performed prior to vaccination (OR: 1.72 [95% CI 0.1.35-2.18] and OR: 1.67 [95% CI 1.30-2.13], respectively). Referred women of all ages had higher use of GP before vaccination. Population attributable fraction analyses indicated that psychiatric medication, hospitalization due to a psychiatric disorder and use of talk therapy, or psychometric test "explained" 13%, 10%, 12% and 11% of the referrals, respectively. Results did not change substantially when adjusted for potential confounders.

CONCLUSION

Women referred to HPV centers because of suspected adverse events after vaccination more often had preexisting psychiatric conditions, psychological symptoms or frequent GP attendance prior to HPV vaccination.

HPV vaccination and risk of chronic fatigue syndrome/myalgic encephalomyelitis: A nationwide register-based study from Norway

BACKGROUND

Vaccination has been suggested to be involved in the aetiology of chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME). HPV vaccine was introduced in the Norwegian Childhood Immunisation Programme and offered 12year old girls from 2009. We studied the association between HPV vaccination and risk of CFS/ME and also assessed medical history in relation to both risk of CFS/ME and HPV vaccine uptake.

METHODS

Individual data from national registries, including the Norwegian Population Registry, the Norwegian Patient Registry and the Norwegian Immunisation Registry were linked using the unique personal identification number. Yearly incidence rates of CFS/ME for 2009-2014 were calculated among the 824,133 boys and girls, aged 10-17 living in Norway during these 6years. A total of 176,453 girls born 1997-2002 were eligible for HPV vaccination and included in further analyses. Hazard ratios (HRs) of CFS/ME were estimated using Cox regression. Risk differences (RDs) of vaccine uptake were estimated with binomial regression.

RESULTS

A similar yearly increase in incidence rate of CFS/ME was observed among girls and boys, IRR=1.15 (95% confidence interval (CI) 1.10-1.19) and 1.15 (95% CI 1.09-1.22), respectively. HPV vaccination was not associated with CFS/ME, HR=0.86 (95% CI 0.69-1.08) for the entire follow-up period and 0.96 (95% CI 0.64-1.43) for the first two years after vaccination. The risk of CFS/ME increased with increasing number of previous hospital contacts, HR=5.23 (95% CI 3.66-7.49) for 7 or more contacts as compared to no contacts. Girls with 7 or more hospital contacts were less likely to be vaccinated than girls with no previous hospital contacts, RD=-5.5% (95% CI -6.7% to -4.2%).

CONCLUSIONS

No indication of increased risk of CFS/ME following HPV vaccination was observed among girls in the first 6 birth cohorts offered HPV vaccine through the national immunisation programme in Norway.