Perception of Human Papillomavirus Infection,Cervical Cancer and HPV Vaccination in North Indian Population

Background

Human Papillomavirus (HPV) -associated cervical cancer is the second-most common cancer in women worldwide but it is the most frequent gynaecological cancer and cancer associated death in India women. The objective of this study was to assess knowledge about cervical cancer, HPV, HPV vaccine, HPV vaccine acceptance among school and undergraduates students and their parent’s perception about acceptance of HPV vaccine in Northern part of India (Delhi and NCR regions).

Materials and Methods

A qualitative questionnaire based survey among 2500 urban/rural students aged 12–22 years was conducted.

Results

Overall, a low frequency (15%) of HPV and cervical cancer awareness was observed in students and their parents. However, the awareness was much higher in females belonging to urban setup compared to boys with a perception that HPV causes cervical cancer in women only. Additionally, only (13%) participants who were aware of cervical cancer and HPV) were willing to accept HPV vaccination. Apparently, parents of female students were two times more willing to accept HPV vaccination for their ward than male students (p<0.001; OR 95%CI = 2.09 (1.58–2.76).

Conclusion

Cervical cancer and HPV awareness among school, undergraduate students and also to their parents was found to be very low in this part of India. The level of awareness and education appears to be insignificant determinants in rural compared to urban setup. Better health education will be needed to maximize public awareness for cervical cancer prevention.     

A Pilot Study to Evaluate an Elementary School-Based Dog Bite Prevention Program

ABSTRACT

The primary objective of this program evaluation was to determine if a school-based education program is an effective means of informing elementary school-aged children enrolled in second through fourth grades about dog bite safety—the awareness of proper behavior when in the company of dogs to prevent bites, injuries, or fatalities. The pilot program, featuring written materials and a video, was developed to teach dog bite safety, and questionnaires were designed to assess the program. Students (n=486) from seven schools from Montgomery and Prince George's Counties in Maryland, USA participated. Pre- and post-program questionnaires assessed students' interactions, encounters, and relationships with dogs, as well as use of program materials, and changes in understanding about dog behavior, body language, and bite avoidance. The program results appeared to be highly effective in helping children understand how to prevent or avoid potentially threatening situations involving dogs. The program was most effective at teaching children that: (1) neighborhood and family dogs are most likely to cause dog bite-related injuries, (2) they should never run away from a dog, and (3) they should never touch a dog that is sleeping or eating. For most groups, there was also an increased level of recognition of canine body language. Almost half of the participants indicated that they had been bitten in the past, and over 80% knew the attacking dog. Finally, the findings suggest that an age-appropriate dog bite safety program delivered in an elementary school setting can be effective in producing awareness about preventing dog bite-related injuries. Future investigations should concentrate on monitoring actual changes in child behavior.     

Risk of Vertical Transmission of Human Papillomavirus throughout Pregnancy: A Prospective Study

Objective

Much controversy still exists about maternal-to-infant transmission of human papillomavirus (HPV) infection, specifically about the magnitude of the risk and the route and timing of such vertical transmission. This prospective cohort study examines the risk of vertical transmission of maternal HPV in each trimester of pregnancy.

Study design

One hundred fifty three healthy pregnant women were followed longitudinally throughout pregnancy and cervical swabs obtained in each trimester and postpartum for HPV detection. Cord blood, neonatal nasopharyngeal aspirates, and placental biopsies were collected at delivery. DNA isolation, polymerase chain reaction, and hybridization were performed using the GG HPV Genotyping Chip Kit (Goodgene Inc., Seoul, Korea). Detection of HPV in neonates was defined as the presence of HPV DNA in either cord blood or neonatal nasopharyngeal aspirate.

Results

HPV DNA was detected in 14%(22/153) of healthy women in the first trimester, 18%(22/124) in the second trimester, and 10%(15/153) in the third trimester; 24%(37/153) were positive for HPV DNA on at least one occasion in pregnancy. At birth, 5.2%(8/153) of neonates were HPV DNA positive. Seven of these eight infants were born to HPV-positive mothers. Placental HPV DNA was positive in 3.3%(5/152) of cases, and all five cases were from mothers with at least one HPV-positive test. Detection of HPV DNA in neonates was associated with detection of HPV in mothers during any of the three trimesters of pregnancy.

Conclusion

HPV DNA was detected at birth in 5.2%(8/153) of neonates born to healthy women, and was associated with the detection of HPV in mothers during any of the three trimesters of pregnancy.     

Patterns of Human Papillomavirus Types in Multiple Infections: An Analysis in Women and Men of the High Throughput Human Papillomavirus Monitoring Study

Background

To evaluate the pattern of co-infection of human papillomavirus (HPV) types in both sexes in Sweden.

Methods

Cell samples from genital swabs, first-void urine, and genital swabs immersed in first-void urine were collected in the present cross-sectional High Throughput HPV Monitoring study. Overall, 31,717 samples from women and 9,949 from men (mean age 25) were tested for 16 HPV types using mass spectrometry. Multilevel logistic regression was used to estimate the expected number of multiple infections with specific HPV types, adjusted for age, type of sample, and accounting for correlations between HPV types due to unobserved risk factors using sample-level random effects. Bonferroni correction was used to allow for multiple comparisons (120).

Results

Observed-to-expected ratio for any multiple infections was slightly above unity in both sexes, but, for most 2-type combinations, there was no evidence of significant departure from expected numbers. HPV6/18 was found more often and HPV51/68 and 6/68 less often than expected. However, HPV68 tended to be generally underrepresented in co-infections, suggesting a sub-optimal performance of our testing method for this HPV type.

Conclusions

We found no evidence for positive or negative clustering between HPV types included in the current prophylactic vaccines and other untargeted oncogenic types, in either sex.     

A Behavioral Group Treatment Program for Menopausal Hot Flashes: Results of a Pilot Study

In the present study, we tested the effectiveness of a cognitive-behavioral group treatment (CBGT) for hot flashes in menopausal women. Treatment was administered over 8, 90 min weekly sessions and consisted of education, relaxation training and cognitive restructuring. Nineteen women meeting STRAW staging criteria for the menopause transition (stages –1 to +1) were randomly assigned to immediate or delayed treatment (wait list) and were asked to monitor their hot flashes and night sweats prospectively. They also completed questionnaires, including the Womens Health Questionnaire and the Menopause Specific Quality of Life Questionnaire to determine psychosocial benefits of treatment. Results suggested that the CBGT was moderately successful in reducing the frequency of total vasomotor symptoms [F (1, 17) = 6.16, p < .01], as measured by daily symptom diaries. While there were arithmetic improvements in psychosocial functioning in this sample, these results were not significant. Despite the limitations of small sample size and possible placebo effect, this pilot study supports the notion that cognitive-behavioral interventions aimed at reducing vasomotor symptoms may be of value for menopausal hot flashes when administered in a small-group format.     

Addressing Health Inequalities in the Delivery of the Human Papillomavirus Vaccination Programme: Examining the Role of the School Nurse

Background

HPV immunisation of adolescent girls is expected to have a significant impact in the reduction of cervical cancer. UK The HPV immunisation programme is primarily delivered by school nurses. We examine the role of school nurses in delivering the HPV immunisation programme and their impact on minimising health inequalities in vaccine uptake.

Methods and Findings

A rapid evidence assessment (REA) and semi-structured interviews with health professionals were conducted and analysed using thematic analysis. 80 health professionals from across the UK are interviewed, primarily school nurses and HPV immunisation programme coordinators. The REA identified 2,795 articles and after analysis and hand searches, 34 relevant articles were identified and analysed. Interviews revealed that health inequalities in HPV vaccination uptake were mainly related to income and other social factors in contrast to published research which emphasises potential inequalities related to ethnicity and/or religion. Most school nurses interviewed understood local health inequalities and made particular efforts to target girls who did not attend or missed doses. Interviews also revealed maintaining accurate and consistent records influenced both school nurses'' understanding and efforts to target inequalities in HPV vaccination uptake.

Conclusions

Despite high uptake in the UK, some girls remain at risk of not being vaccinated with all three doses. School nurses played a key role in reducing health inequalities in the delivery of the HPV programme. Other studies identified religious beliefs and ethnicity as potentially influencing HPV vaccination uptake but interviews for this research found this appeared not to have occurred. Instead school nurses stated girls who were more likely to be missed were those not in education. Improving understanding of the delivery processes of immunisation programmes and this impact on health inequalities can help to inform solutions to increase uptake and address health inequalities in childhood and adolescent vaccination programmes.     

Costs and Cost-Effectiveness of 9-Valent Human Papillomavirus (HPV) Vaccination in Two East African Countries

Background

Current prophylactic vaccines against human papillomavirus (HPV) target two of the most oncogenic types, HPV-16 and -18, which contribute to roughly 70% of cervical cancers worldwide. Second-generation HPV vaccines include a 9-valent vaccine, which targets five additional oncogenic HPV types (i.e., 31, 33, 45, 52, and 58) that contribute to another 15–30% of cervical cancer cases. The objective of this study was to determine a range of vaccine costs for which the 9-valent vaccine would be cost-effective in comparison to the current vaccines in two less developed countries (i.e., Kenya and Uganda).

Methods and Findings

The analysis was performed using a natural history disease simulation model of HPV and cervical cancer. The mathematical model simulates individual women from an early age and tracks health events and resource use as they transition through clinically-relevant health states over their lifetime. Epidemiological data on HPV prevalence and cancer incidence were used to adapt the model to Kenya and Uganda. Health benefit, or effectiveness, from HPV vaccination was measured in terms of life expectancy, and costs were measured in international dollars (I$). The incremental cost of the 9-valent vaccine included the added cost of the vaccine counterbalanced by costs averted from additional cancer cases prevented. All future costs and health benefits were discounted at an annual rate of 3% in the base case analysis. We conducted sensitivity analyses to investigate how infection with multiple HPV types, unidentifiable HPV types in cancer cases, and cross-protection against non-vaccine types could affect the potential cost range of the 9-valent vaccine. In the base case analysis in Kenya, we found that vaccination with the 9-valent vaccine was very cost-effective (i.e., had an incremental cost-effectiveness ratio below per-capita GDP), compared to the current vaccines provided the added cost of the 9-valent vaccine did not exceed I$9.7 per vaccinated girl. To be considered very cost-effective, the added cost per vaccinated girl could go up to I$5.2 and I$16.2 in the worst-case and best-case scenarios, respectively. At a willingness-to-pay threshold of three times per-capita GDP where the 9-valent vaccine would be considered cost-effective, the thresholds of added costs associated with the 9-valent vaccine were I$27.3, I$14.5 and I$45.3 per vaccinated girl for the base case, worst-case and best-case scenarios, respectively. In Uganda, vaccination with the 9-valent vaccine was very cost-effective when the added cost of the 9-valent vaccine did not exceed I$8.3 per vaccinated girl. To be considered very cost-effective, the added cost per vaccinated girl could go up to I$4.5 and I$13.7 in the worst-case and best-case scenarios, respectively. At a willingness-to-pay threshold of three times per-capita GDP, the thresholds of added costs associated with the 9-valent vaccine were I$23.4, I$12.6 and I$38.4 per vaccinated girl for the base case, worst-case and best-case scenarios, respectively.

Conclusions

This study provides a threshold range of incremental costs associated with the 9-valent HPV vaccine that would make it a cost-effective intervention in comparison to currently available HPV vaccines in Kenya and Uganda. These prices represent a 71% and 61% increase over the price offered to the GAVI Alliance ($5 per dose) for the currently available 2- and 4-valent vaccines in Kenya and Uganda, respectively. Despite evidence of cost-effectiveness, critical challenges around affordability and feasibility of HPV vaccination and other competing needs in low-resource settings such as Kenya and Uganda remain.     

Human Papillomavirus Infection and Fertility Alteration: A Systematic Review

BackgroundHPV is the most prevalent sexually transmitted infection and its effect in cancer induction is well documented. HPV infections are mostly asymptomatic, but it is unclear whether HPV infections can result in alterations of reproductive health.ObjectiveTo determine the relationship between human papillomavirus infections and reproductive health in both men and women.MethodsA systematic literature review was performed in PubMed and ScienceDirect data bases from January 1994 through August 2014.ResultsHPV infections are shown to be significantly associated to many adverse effects in the reproductive function. These adverse effects were reported in different levels from cells production to pregnancy and may be related to the infecting genotype.ConclusionsIt appears from this study that HPV detection and genotyping could be of great value in infertility diagnosis at least in idiopathic infertility cases. Like for the risk of carcinogenesis, another classification of HPV regarding the risk of fertility alteration may be considered after deep investigations.     

Human toxocariasis: a seroepidemiological survey in schoolchildren of Sorocaba, Brazil

A seroepidemiological survey for toxocariasis, among 180 schoolchildren of the public schools of Sorocaba City, state of S?o Paulo, Brazil, was carried out from August 2000 to July 2001. ELISA test was performed using excretory and secretory antigens for the detection of IgG anti-Toxocara antibodies. Information regarding the children was obtained from the parents or legal guardians. The results showed that the mean age was 5.4 +/- 1.4 years, the infection coefficient (IC) was 38.3 and the infection risk was higher among the children living in the city outskirts (IC = 47.4) where the socioeconomic conditions were worse than in the central region of the city (IC = 11.1). There was an association between higher frequency of seroreactivity in the ELISA test and the condition of living in a house with a yard and/or unpaved street. The same was observed in relation to a history of enteroparasitism. There was also an association between a seronegative ELISA test and previous treatment of pet dogs and/or cats with vermifuge. Based on these results, the authors propose that public health programs should include anthelmintic for dogs and cats during the antirabies vaccination campaigns, in order to diminish environmental contamination with Toxocara spp. eggs and consequently human infection.     

Genotype-Specific Incidence and Clearance of Human Papillomavirus in Oral Mucosa of Women: A Six-Year Follow-Up Study

Background

There are no previous longitudinal studies on genotype-specific natural history of human papillomavirus (HPV) infections in oral mucosa of women.

Methods

In the Finnish Family HPV Study, 329 pregnant women were enrolled and followed up. HPV-genotyping of oral scrapings was performed with nested PCR and Multimetrix® test (Progen, Heidelberg, Germany). Incidence and clearance times and rates for each HPV-genotype identified in oral mucosa were determined. Predictors for incident and cleared HPV infections for species 7/9 genotypes were analyzed using Poisson regression model.

Results

Altogether, 115 baseline HPV-negative women acquired incident oral HPV infection, and 79 women cleared their infection. HPV16 and multiple HPVs most frequently caused incident infections (65% and 12%) in 13.3 and 17.1 months respectively, followed by HPV58, HPV18 and HPV6 (close to 5% each) in 11–24 months. HPV58, HPV18 and HPV66 were the most common to clear. HPV6 and HPV11 had the shortest clearance times, 4.6 months and 2.5 months, and the highest clearance rates, 225.5/1000 wmr and 400/1000 wmr, respectively. The protective factors for incident oral HPV-species 7/9 infections were 1) new pregnancy during follow-up and 2) having the same sexual partner during FU. Increased clearance was related with older age and a history of atopic reactions, whereas previous sexually transmitted disease and new pregnancy were associated with decreased clearance.

Conclusions

HPV16 was the most frequent genotype to cause an incident oral HPV-infection. Low risk HPV genotypes cleared from oral mucosa more quickly than high risk HPV genotypes. Pregnancy affected the outcome of oral HPV infection.     

快速检测尖锐湿疣组织中人乳头瘤病毒6型和11型DNA的研究

本文应用聚合酶链反应技术对30例人生殖器尖锐湿疣 组织中HPV6,11DNA的存在进行了检测研究。结果发现HPV6,HPV11DNA的阳性率分别为60×,90％HPV6,HPV11DNA双重检出率为53．3％,总阳性率达96．67％,本文结果证实HPV6,11的感染和尖锐湿疣的发生密切相关。本文检测方法具有快速、灵敏、特异性强的优点,为HPVDNA的检测及其分型研究提供了有效的手段。作者还对两例女阴假性湿疣进行PCR扩增,结果似乎不支持女阴假性湿疣的HPV感染的病因学。     

Human Papillomavirus Infection and Vaccination: Awareness and Knowledge of HPV and Acceptability of HPV Vaccine among Mothers of Teenage Daughters in Weihai,Shandong, China

In preparation for the introduction of human papillomavirus (HPV) vaccine, we investigated awareness and knowledge of HPV/HPV vaccine and potential acceptability to HPV vaccine among mothers with a teenage daughter in Weihai, Shandong, China. A cross-sectional survey was conducted in 2013 with a sample of 1850 mothers who had a daughter (aged 9–17 years) attending primary, junior and senior high schools. In the final sample (N = 1578, response rate 85.30%), awareness of HPV was reported by 305 (19.32%) mothers. Awareness varied significantly by daughter’s age (P<0.01), mother’s education level (P<0.01), mother’s occupation (P<0.01), household income (P<0.01) and residence type (P<0.01). Knowledge about HPV/HPV vaccine was poor with a mean total score of 3.56 (SD = 2.40) out of a possible score of 13. Mothers with a higher education level reported higher levels of knowledge (P = 0.02). Slightly more than one-fourth (26.49%) of mothers expressed their potential acceptability of HPV vaccine for their daughters. Acceptability increased along with increased daughters’ age (P<0.01), household income (P<0.01) and knowledge level (P<0.01). House wives and unemployed mothers had the highest acceptability (P<0.01). The most common reasons for not accepting HPV vaccination were “My daughter is too young to have risk of cervical cancer (30.95%)”, “The vaccine has not been widely used, and the decision will be made after it is widely used (24.91%)”, “Worry about the safety of the vaccine (22.85%)”. Awareness and knowledge of HPV/HPV vaccines are poor and HPV vaccine acceptability is low among these Chinese mothers. These results may help inform appropriate health education programs in this population.     

Sleep,School Performance,and a School-Based Intervention among School-Aged Children: A Sleep Series Study in China

Background

Sufficient sleep during childhood is essential to ensure a transition into a healthy adulthood. However, chronic sleep loss continues to increase worldwide. In this context, it is imperative to make sleep a high-priority and take action to promote sleep health among children. The present series of studies aimed to shed light on sleep patterns, on the longitudinal association of sleep with school performance, and on practical intervention strategy for Chinese school-aged children.

Methods and Findings

A serial sleep researches, including a national cross-sectional survey, a prospective cohort study, and a school-based sleep intervention, were conducted in China from November 2005 through December 2009. The national cross-sectional survey was conducted in 8 cities and a random sample of 20,778 children aged 9.0±1.61 years participated in the survey. The five-year prospective cohort study included 612 children aged 6.8±0.31 years. The comparative cross-sectional study (baseline: n = 525, aged 10.80±0.41; post-intervention follow-up: n = 553, aged 10.81±0.33) was undertaken in 6 primary schools in Shanghai. A battery of parent and teacher reported questionnaires were used to collect information on children’s sleep behaviors, school performance, and sociodemographic characteristics. The mean sleep duration was 9.35±0.77 hours. The prevalence of daytime sleepiness was 64.4% (sometimes: 37.50%; frequently: 26.94%). Daytime sleepiness was significantly associated with impaired attention, learning motivation, and particularly, academic achievement. By contrast, short sleep duration only related to impaired academic achievement. After delaying school start time 30 minutes and 60 minutes, respectively, sleep duration correspondingly increased by 15.6 minutes and 22.8 minutes, respectively. Moreover, intervention significantly improved the sleep duration and daytime sleepiness.

Conclusions

Insufficient sleep and daytime sleepiness commonly existed and positively associated with the impairment of school performance, especially academic achievement, among Chinese school-aged children. The effectiveness of delaying school staring time emphasized the benefits of optimal school schedule regulation to children’s sleep health.     

Cost of Preventing,Managing, and Treating Human Papillomavirus (HPV)-Related Diseases in Sweden before the Introduction of Quadrivalent HPV Vaccination

Objective

Costs associated with HPV-related diseases such as cervical dysplasia, cervical cancer, and genital warts have not been evaluated in Sweden. These costs must be estimated in order to determine the potential savings if these diseases were eradicated and to assess the combined cost-effectiveness of HPV vaccination and cervical cancer screening. The present study aimed to estimate prevention, management, and treatment costs associated with cervical dysplasia, cervical cancer, and genital warts from a societal perspective in Sweden in 2009, 1 year before the quadrivalent HPV vaccination program was implemented.

Methods and Materials

Data from the Swedish cervical cancer screening program was used to calculate the costs associated with prevention (cytological cervical cancer screening), management (colposcopy and biopsy following inadequate/abnormal cytological results), and treatment of CIN. Swedish official statistics were used to estimate treatment costs associated with cervical cancer. Published epidemiological data were used to estimate the number of incident, recurrent, and persistent cases of genital warts; a clinical expert panel assessed management and treatment procedures. Estimated visits, procedures, and use of medications were used to calculate the annual cost associated with genital warts.

Results

From a societal perspective, total estimated costs associated with cervical cancer and genital warts in 2009 were €106.6 million, of which €81.4 million (76%) were direct medical costs. Costs associated with prevention, management, and treatment of CIN were €74 million; screening and management costs for women with normal and inadequate cytology alone accounted for 76% of this sum. The treatment costs associated with incident and prevalent cervical cancer and palliative care were €23 million. Estimated costs for incident, recurrent and persistent cases of genital warts were €9.8 million.

Conclusion

Prevention, management, and treatment costs associated with cervical dysplasia, cervical cancer, and genital warts are substantial. Defining these costs is important for future cost-effectiveness analyses of the quadrivalent HPV vaccination program in Sweden.     

Reduced Prevalence of Oral Human Papillomavirus (HPV) 4 Years after Bivalent HPV Vaccination in a Randomized Clinical Trial in Costa Rica

Background

Human papillomavirus (HPV) infection, particularly with type 16, causes a growing fraction of oropharyngeal cancers, whose incidence is increasing, mainly in developed countries. In a double-blind controlled trial conducted to investigate vaccine efficacy (VE) of the bivalent HPV 16/18 vaccine against cervical infections and lesions, we estimated VE against prevalent oral HPV infections 4 years after vaccination.

Methods and Findings

A total of 7,466 women 18–25 years old were randomized (1∶1) to receive the HPV16/18 vaccine or hepatitis A vaccine as control. At the final blinded 4-year study visit, 5,840 participants provided oral specimens (91·9% of eligible women) to evaluate VE against oral infections. Our primary analysis evaluated prevalent oral HPV infection among all vaccinated women with oral and cervical HPV results. Corresponding VE against prevalent cervical HPV16/18 infection was calculated for comparison. Oral prevalence of identifiable mucosal HPV was relatively low (1·7%). Approximately four years after vaccination, there were 15 prevalent HPV16/18 infections in the control group and one in the vaccine group, for an estimated VE of 93·3% (95% CI = 63% to 100%). Corresponding efficacy against prevalent cervical HPV16/18 infection for the same cohort at the same visit was 72·0% (95% CI = 63% to 79%) (p versus oral VE = 0·04). There was no statistically significant protection against other oral HPV infections, though power was limited for these analyses.

Conclusions

HPV prevalence four years after vaccination with the ASO4-adjuvanted HPV16/18 vaccine was much lower among women in the vaccine arm compared to the control arm, suggesting that the vaccine affords strong protection against oral HPV16/18 infection, with potentially important implications for prevention of increasingly common HPV-associated oropharyngeal cancer.ClinicalTrials.gov, Registry number {"type":"clinical-trial","attrs":{"text":"NCT00128661","term_id":"NCT00128661"}}NCT00128661     

Long-Term Protection against Diphtheria in the Netherlands after 50 Years of Vaccination: Results from a Seroepidemiological Study

Background and Aims

To evaluate the National Immunisation Programme (NIP) a population-based cross-sectional seroepidemiological study was performed in the Netherlands. We assessed diphtheria antitoxin levels in the general Dutch population and in low vaccination coverage (LVC) areas where a relatively high proportion of orthodox Protestants live who decline vaccination based on religious grounds. Results were compared with a nationwide seroepidemiological study performed 11 years earlier.

Methods

In 2006/2007 a national serum bank was established. Blood samples were tested for diphtheria antitoxin IgG concentrations using a multiplex immunoassay for 6383 participants from the national sample (NS) and 1518 participants from LVC municipalities. A cut-off above 0.01 international units per ml (IU/ml) was used as minimum protective level.

Results

In the NS 91% of the population had antibody levels above 0.01 IU/ml compared to 88% in the 1995/1996 serosurvey (p<0.05). On average, 82% (vs. 78% in the 1995/1996 serosurvey, p<0.05) of individuals from the NS born before introduction of diphtheria vaccination in the NIP and 46% (vs. 37% in the 1995/1996 serosurvey, p = 0.11) of orthodox Protestants living in LVC areas had antibody levels above 0.01 IU/ml. Linear regression analysis among fully immunized individuals (six vaccinations) without evidence of revaccination indicated a continuous decline in antibodies in both serosurveys, but geometric mean antibodies remained well above 0.01 IU/ml in all age groups.

Conclusions

The NIP provides long-term protection against diphtheria, although antibody levels decline after vaccination. As a result of natural waning immunity, a substantial proportion of individuals born before introduction of diphtheria vaccination in the NIP lack adequate levels of diphtheria antibodies. Susceptibility due to lack of vaccination is highest among strictly orthodox Protestants. The potential risk of spread of diphtheria within the geographically clustered orthodox Protestant community after introduction in the Netherlands has not disappeared, despite national long-term high vaccination coverage.