Universal Vaccination Program Research Articles

Re-thinking breast and cervical cancer preventive campaigns in developing countries: the case for interventions at high schools

BackgroundThe negative impact of cervical and breast cancers in low and lower-middle income countries are worsening, and, along with other non-communicable diseases, occur disproportionately in these resource-limited economies. Most preventive approaches to these cancers require government funding, but few countries with the most at-risk population can afford government-sponsored universal vaccination, screening, diagnostic and treatment programmes, which, along with socioeconomic issues, contribute to the poor outcomes in these mostly developing countries. An urgent need exists, therefore, to find an effective, affordable, cost-effective, culturally-acceptable and sustainable way of reducing these cancers. This paper advocates a re-thinking in the current preventive campaigns.Main bodyUsing evidence provided by recently-published papers, a case is made for enlightenment campaigns to primarily target teenagers (boys and girls) in high schools of developing countries. Inclusions into the schools’ academic curricula are the recommended approach, given that both cancers take hold on populations within that age bracket.This approach, if adopted, may be the only accessible, affordable and realistic approach that gives millions of women in low and lower-middle income countries the chance at survival. Empowering them early instils the self-awareness and confidence necessary for young adults to take charge of their own health. The acquired knowledge, in turn, helps them adopt positive attitudes and preventive behaviours that will, ultimately, prolong their lives.ConclusionThe recommended approach offers governments and concerned stakeholders an evidence-based option that allows them to deliver cost-effective and sustainable life-saving interventions, while hoping to get around the bottlenecks that limit the large scale implementation of other effective but capital-intensive strategies.

Public health impact model estimating the impact of introducing an adjuvanted recombinant zoster vaccine into the UK universal mass vaccination programme

ObjectivesIn 2013, the herpes zoster (HZ) immunisation programme was introduced in the UK, recommending vaccination of adults 70 years of age (YOA) with the zoster vaccine live (ZVL), the only...

The association between body mass index and anal canal human papillomavirus prevalence and persistence: the HIM study

ABSTRACT Background: While receptive anal sex is an established risk factor for anal human papillomavirus (HPV) infection and squamous cell carcinoma of the anus (SCCA), people with anal HPV infection and SCCA commonly report no lifetime receptive anal sex suggesting other factors may also increase risk for anal HPV infection and persistence. Given potential associations between obesity and conditions that may cause perianal or anal canal lesions, we hypothesized that body mass index (BMI) was associated with HPV infection. Methods: Genotyping for 36 HPV types was conducted on anal canal specimens from men, ages 18–70, from Brazil, Mexico, and the USA. Eligibility included no history of genital warts or HIV. Evaluable specimens were collected from 328 men having sex with men (MSM) and 1348 men having sex with women (MSW) who reported no lifetime receptive anal sex. Prevalence of anal HPV infection and six-month persistence by BMI were estimated in addition to adjusted prevalence ratios for the association between BMI and HPV infection. Results: Among MSW, obese men had a higher prevalence of HPV-16 in the anal canal (3.1%), compared to normal weight men (1.3%) although 95% CI overlapped. Among MSM, prevalence of HPV decreased with increasing BMI. A similar pattern was observed for persistence. After adjustment for confounders, obese MSW had 2.4 times higher odds of HPV-16 compared to normal weight men. Conclusions: BMI may be positively associated with anal HPV (especially HPV-16) among MSW and negatively associated with anal HPV among MSM which supports continued universal HPV vaccination programs.

Mass migration to Europe: an opportunity for elimination of hepatitis B virus?

People from low-to-middle income countries have been migrating to western Europe on a large scale in recent years. Data indicate that the number of first-time asylum applications by non-EU members increased from 290 000 in 2011 to more than 1·3 million in 2015. During the peak period of migration, The Global Health Sector Strategy on Viral Hepatitis was adopted by WHO. Viral hepatitis, and particularly hepatitis B virus (HBV), is an important disease because of its high prevalence and associated mortality. In some cases, HBV can be carried by refugees arriving from regions of high and intermediate prevalence. Refugees with HBV might not show clinical symptoms and not be diagnosed in destination countries with a low prevalence, where screening is not regularly done. Although transmission to the host population is low, dedicated surveillance and tailored public health policies are required. It is important to note that some of the countries that receive many migrants do not have a universal HBV vaccination programme. In this Viewpoint, we argue that the current large-scale movement from regions with high or intermediate HBV prevalence should be taken as an opportunity to achieve viral hepatitis elimination targets, by establishing a well prepared infrastructure for HBV screening, vaccination, and treatment.

Hepatitis B virus surface gene mutants in immunoprophylaxis-failed infants from Southern China.

Hepatitis B virus (HBV) vaccination was considered the most powerful tool for prevention of HBV transmission from mother to infant. In 1992, a universal HBV vaccination program for infants was launched in China. The aim of this study was to investigate the HBV surface antigen (HBsAg) variations in immunoprophylaxis-failed infants, vaccine free infant patients and adult chronic hepatitis B (CHB) patients (without nucleoside analog treatment). Immunoprophylaxis-failed infants were recruited from two centers (Guangdong and Chongqing, representing Southern China). HBV serum markers, including HBsAg, hepatitis e antigen (HBeAg), and core antigen, were detected by the enzyme-linked immunosorbent assay. HBV DNA load was detected by quantitative polymerase chain reaction. Nucleotide sequences encoding HBsAg were amplified and analyzed. Frequencies of amino acid substitutions within the second loop of "a" determinant (region with greater local hydrophilicity) in immunoprophylaxis-failed infants were clearly higher than the unvaccinated infant patients and adult CHB patients (9.6% vs 0% vs 3.8%; χ 2 = 7.454; P = 0.024). More than 50% (52.8%) aa substitutions in immunoprophylaxis-failed infants were located in B cell epitopes, while 64.6% aa substitutions in adult CHB patients were located in CTL cell epitopes. HBeAg negative patients had higher substitution frequency in CTL and Th cell epitopes, and in immunoprophylaxis-failed infant patients with substitution in major hydrophilic region region had a higher alanine aminotransferase level (68.6 ± 111.5 vs 62.1 ± 132.2; P = 0.026), and lower DNA load (7.03 ± 1.72 vs 7.82 ± 1.73; P < 0.001). In conclusion, our results observed vaccine-induced immune selection pressure in vaccine failed infants, substitutions in "a" determinant, especially the G145 substitution was still the most stable and remarkable site of vaccine escape.

China's hepatitis B burden and expectation on 40 years of trials and tribulations

Since the 40th anniversary of China's reform and opening-up, earth-shattering development has taken place in all walks of life across the country. Research field on the prevention and treatment of chronic hepatitis B has been rewarding after 40 years of trials and tribulations. Additionally, hepatitis B vaccination program and effective antiviral therapy has amazingly reduced the prevalence of hepatitis B virus infection. Coupled with the literary evidence, a consensus has gradually emerged in the field of anti-HBV treatment that "high potency, low incidence of drug resistance and immunomodulation coexists". We believe that in the near future, according to the principle of "prevention first, prevention with treatment", universal vaccination program for infants, vaccination of high-risk groups, active treatment of HBV carriers and chronic hepatitis B patients, and the realization of "early screening, diagnosis and treatment" of hepatocellular carcinoma will eradicate HBV infection.

Determinants of Seasonal Influenza Vaccine Uptake Among the Elderly in the United States: A Systematic Review and Meta-Analysis.

Background: Despite the availability of a universal influenza vaccination program in the United States and Canada, seasonal influenza vaccine (SIV) uptake among the elderly remains suboptimal. Understanding the factors that determine SIV uptake in this important population subgroup is essential for designing effective interventions to improve seasonal influenza vaccination among the elderly. We evaluated the determinants of SIV uptake in the elderly in the United States and Canada. Methods: We systematically searched relevant bibliographic databases and websites from 2000 to 2017 for population-based clinical trials or observational studies conducted in community-based elderly individuals in the United States or Canada, irrespective of health status. Two reviewers independently screened the identified citations for eligibility using a two-stage sifting approach to review the title/abstract and full-text article. We gathered data on determinants of uptake (any vaccine receipt) and adherence (receipt of vaccine in more than one season) to seasonal influenza vaccination. Where possible, we pooled the data using inverse variance methods to minimize the variance of the weighted average. Results: Five cross-sectional studies on SIV uptake (none on adherence) from the United States met our eligibility criteria. Being older (pooled odds ratio [POR] = 1.44, 95% Confidence Interval [CI] = 1.11, 1.86); White (POR = 1.33, 95% CI = [1.10, 1.64]); and having higher income (POR = 1.06, 95% CI = [1.04, 1.09]); and health insurance (POR = 1.40, 95% CI = [1.25, 1.55]) were associated with increased SIV uptake. Conclusion: Older, ethnically White, higher income elderly individuals with access to health insurance coverage and a regular health care provider have higher SIV uptake in the United States. There was limited evidence for other socioeconomic and health-related determinants. Further studies are needed to provide an evidence base for planning more effective influenza vaccination programs in the United States.

Chronic hepatitis B prevalence in Australian Aboriginal and Torres Strait Islander people before and after implementing a universal vaccination program: a systematic review and meta-analysis.

Embase, Medline and Web of Science were searched from 1 January 1981 to 29 March 2018 and all issues of the Northern Territory and New South Wales Public Health Bulletins. Studies needed to report the number of individuals who were tested and tested positive for hepatitis B surface antigen (HBsAg). There were 36 studies; 16 before and 20 after 2000; reporting 84 prevalence estimates. Population groups included: adults (14 studies), pregnant women (13 studies), prisoners (five studies) children or teenagers (10 studies) and infants (two studies). The pooled prevalence of HBsAg decreased overall (from 10.8% before 2000 vs 3.5% after 2000), in women (4.2% vs 2.2%), in males (17.5% vs 3.5%), in regional (7.8% vs 3.9%) and remote (14.4% vs 5.7%) areas, in New South Wales (12.3% vs 3.0%), in the Northern Territory (6.1% vs 5.1%), in adults (15.3% vs 4.3%) and in pregnant women (3.6% vs 2.6%). The prevalence of HBsAg decreased among Aboriginal people after 2000.

The Impact of Universal Infant Hepatitis B Immunization on Reducing the Hepatitis B Carrier Rate in Pregnant Women.

The hepatitis B virus (HBV) status of pregnant women affects HBV vaccine failure in their offspring. This study is aimed to investigate the impact of the universal infant HBV vaccination program on the long-term hepatitis B surface antigen (HBsAg) rate in pregnant women. Using the National Immunization Information System, we examined a 32-year period of cross-sectional data on a maternal HBsAg and hepatitis B e antigen (HBeAg) screening program launched in July 1984. An age-period-cohort model analysis of 940 180 pregnant women screened for July 1996-June 1997 and the years 2001, 2006, 2011, and 2016 was applied. The annual HBsAg- and HBeAg-seropositive rates decreased from 13.4% and 6.4%, respectively, for the period 1984-1985 to 5.9% and 1.0% in 2016 (P for both trends < .0001). Pregnant women with birth years after July 1986 (the HBV vaccination cohort) had the lowest relative risk (0.27 [95% confidence interval, .26-.28]) of HBsAg positivity compared with birth years before June 1984. The birth cohort effect in relation to the universal infant HBV immunization program has effectively reduced the HBV carrier rate in pregnant women and the burden of perinatal HBV infection on the next generation.

Prevalence and incidence of anal human papillomavirus infection in Mexican men: Need for universal prevention policies.

Describe the natural history of anal HPV among men. Prospective study among men 18-70 years (n=665), from Cuernavaca, Mexico who completed questionnaires and provided specimens (HPV genotyped) at enrollment and 1+ follow-up visit. HPV prevalence and incidence were estimated. Prevalence ratios were calculated with Poisson regression using robust variance estimation. Person-time for incident HPV infection was estimated using number of events modeled as Poisson variable for total person-months. Anal infection prevalence: any HPV type=15%, high-risk=8.4%, HPV16=1.4%, tetravalent vaccine types (4vHPV)=4.4%, nonavalent vaccine types (9vHPV)=6.3%. Factors associated with prevalence: 50+ lifetime female sex partners (adjusted prevalence ratio, a PR=3.25, 95% CI:1.12- 9.47), 10+ lifetime male sex partners (aPR=3.06, 95%CI:1.4- 6.68), and 1+ recent male anal sex partners (aPR=2.28, 95%CI:1.15-4.5). Anal incidence rate: high-risk HPV=7.8/1000 person-months (95%CI:6.0-10.1), HPV16=1.8/1000 personmonths (95%CI:1.1-2.9),4vHPV=3.4/1000 person-months (95%CI:2.3-4.9) and 9vHPV=5.5/1000 person-months (95%CI:4.1-7.5). Implementation of universal HPV vaccination programs, including men, is a public health priority.

Current evidence on the management of hepatitis B in pregnancy.

Hepatitis B virus (HBV) infection is one of the main public health problems across the globe, since almost one third of the world population presents serological markers of contact with the virus. A profound impact on the epidemiology has been exerted by universal vaccination programmes in many countries, nevertheless the infection is still widespread also in its active form. In the areas of high endemicity (prevalence of hepatitis B surface antigen positivity > 7%), mother-to-child transmission represents the main modality of infection spread. That makes the correct management of HBV in pregnancy a matter of utmost importance. Furthermore, the infection in pregnancy needs to be carefully assessed and handled not only with respect to the risk of vertical transmission but also with respect to gravid women health. Each therapeutic or preventive choice deserves to be weighed upon attentively. On many aspects evidence is scarce or controversial. This review will highlight the latest insights into the paramount steps in managing HBV in pregnancy, with particular attention to recommendations from recent guidelines and data from up-do-date research syntheses.

Study of Serologic Response Rate to Haemophilus influenzae Type B After Administration of the Third Dose of Pentavalent Vaccine in Children Aged 12 Months in Karaj City in 2016

Background: Hib conjugate vaccine has led to more than 90% decline in the prevalence of severe Hib diseases in countries with universal coverage vaccination program. After the addition of Hib vaccine to the national vaccination program with 3P (three doses of 2, 4, and 6 months) in IR Iran, we decided to study the vaccine efficacy after the last dose of vaccine in Iranian children in 2016. Methods: 500 blood samples were collected from one-year-old children who referred to the health care centers in Karaj. Demographic information was gathered by a questionnaire. Blood samples were sent to a laboratory for antibody titer determination by ELISA method. Results: 41.2% of the children (95% CI: 36.89 - 45.51) had a titre of IgG against Hib (0.15 to 1 µg/mL) (short-term protection) and 57.4% of the children had a titre of IgG against Hib (95% CI: 53.07 - 61.73) equal to or greater than 1 µg/mL (long-term protection). Antibody GMT was 6.92 µg/mL (95% CI: 6.76 - 7.08). There was no significant correlation between the titer of H. influaenza antibody and demographic factors. Conclusions: In spite of the acceptable GMT titer, children who had antibody titer of < 1 µg/mL comprised approximately 40% of the study population, showing the necessity of further investigation to assess the need for H.flu booster administration.

Oral administration of a chimeric Hepatitis B Virus S/preS1 antigen produced in lettuce triggers infection neutralizing antibodies in mice

Hepatitis B Virus (HBV) infection can be prevented by vaccination. Vaccines containing the small (S) envelope protein are currently used in universal vaccination programs and achieve protective immune response in more than 90% of recipients. However, new vaccination strategies are necessary for successful immunization of the remaining non- or low-responders. We have previously characterized a novel HBV chimeric antigen, which combines neutralization epitopes of the S and the preS1 domain of the large (L) envelope protein (genotype D). The S/preS121–47 chimera produced in mammalian cells and Nicotiana benthamiana plants, induced a significantly stronger immune response in parenterally vaccinated mice than the S protein. Here we describe the transient expression of the S/preS121–47 antigen in an edible plant, Lactuca sativa, for potential development of an oral HBV vaccine. Our study shows that oral administration of adjuvant-free Lactuca sativa expressing the S/preS121–47 antigen, three times, at 1 μg/dose, was sufficient to trigger a humoral immune response in mice. Importantly, the elicited antibodies were able to neutralize HBV infection in an NTCP-expressing infection system (HepG2-NTCP cell line) more efficiently than those induced by mice fed on Lactuca sativa expressing the S protein. These results support the S/preS121–47 antigen as a promising candidate for future development as an edible HBV vaccine.

Cost-effectiveness estimates of vaccination against rotavirus in Piedmont, Italy.

Rotavirus-induced gastroenteritis (RVGE) represents the most frequent form of severe gastroenteritis in children. In such a scenario, the availability of an efficient anti-Rotavirus (anti-RV) vaccine represents an effective prevention tool able to prevent those complications mainly linked to the moderate-severe forms of this disease, which require hospital care. The aim of the present study is to estimate the cost effectiveness of universal routine infant RV vaccination program and its budget impact on the Regional Health Service (RHS) of Piedmont, Italy, in order to evaluate the opportunity of the implementation of a national anti-Rotavirus vaccination programme. The researchers performed a cost-effectiveness analysis comparing costs and benefits of a Rotarix two-dose vaccination versus non vaccination and a budget impact analysis (BIA), complementary to the cost-effectiveness analysis. Our results show that the mass implementation of an anti-RV vaccination in Piedmont, in addition to the expected public health benefits, also allows the RHS to save a considerable amount of money within a short period of time, due to the remarkable reduction of direct health costs associated with RVGE management. In fact, as the analysis shows, a universal vaccination against RV results in money-saving for the RHS already from the 2nd year (with a vaccination coverage of 50%). During the five year period, the active and free offer of the anti-RV vaccination would determine a total saving for RHS of about € 503.000. The cost-effectiveness analysis results showed a cost-saving ICER (incremental cost-effectiveness ratio) relevant to the RHS and equal to - €12.197/QALY. In conclusion the adoption of a universal preventive strategy for all the infants in the Piedmont Region may contribute significantly towards the control of RVGE incidence, thus allowing a noteworthy saving of economic and social resources for both the RHS and the general public.

Evolution of Pneumococcal Vaccine introduction in Childhood and Older Adult National Immunization Programs in Latin America and the Caribbean

Background: In Latin America and the Caribbean (LAC), Streptococcus pneumoniae is associated with an important burden of disease and mortality. The highest incidence of invasive disease and fatality occur at the extremes of life (the first 12 months of life and 65 years or older). In 2007, WHO recommended that all countries should include pneumococcal conjugate vaccine (PCV) as part of their childhood national immunization program (NIP). Since then, PCV uptake globally has occurred rapidly. In 2015, PAHO launched the 2015-2020 Regional Immunization Action Plan which promotes universal and equitable access to immunization services throughout the life cycle. The objective of this review is to describe the evolution of the incorporation of publicly funded pneumococcal immunization in childhood and older adults in LAC NIPs since their recommendation by WHO or PAHO. Methods & Materials: A comprehensive search was done of official national government websites and the country profiles in the WHO immunization monitoring system. Results: Currently, 36 LAC countries/territories have introduced PCV10 or PCV13 in their routine childhood NIP representing 98% of the region's birth cohort (10.8 million). The majority of the countries/territories use PCV13, with the exception of Brazil, Colombia and Ecuador, which use PCV10. All NIPs have a 3-dose schedule (either 2+1 or 3+0). A total of 8 countries have a universal funded program for older adults for 60 or 65 years and older, representing 30% of the region's cohort population (22 and 15 million, respectively). Six countries have pneumococcal polysaccharide vaccine (PPV23) (Chile, Costa Rica, Mexico, Nicaragua, Paraguay, and Uruguay) and two countries fund a sequential regimen with PCV13+PPV23 (Argentina and Panamá). Some countries have implemented or extended funding of pneumococcal immunization to high risk patients. Conclusion: Fast and efficient PCV introduction in infants has occurred since 2007 following WHO/PAHO recommendations. Unlike the introduction of pneumococcal vaccine in childhood in LAC NIPs, only a few countries in LAC have introduced a universal pneumococcal vaccination program for older adults in their NIPs. Infant and older adult cohorts that could potentially benefit from a publicly funded pneumococcal vaccination NIP represent around 98% and 30% of the referenced populations, respectively.

Pneumococcal disease mortality in children < 5 years of age after pneumococcal conjugate vaccine introduction in colombia: a time-trend analysis, 2005-2016

Background: Pneumonia has been one of leading causes of childhood mortality in Colombia. Since 2006, the Colombian Ministry of Health recommends pneumococcal conjugate vaccine (PCV) to high-risk groups. The universal mass vaccination program was fully implemented in 2011 (2-4-12-month schedule). In 2012, Pneumococcal polysaccharide protein D-conjugate vaccine replaced the use of 7-valent PCV. The aim of the current study is to describe trends in pneumonia-related mortality in Colombian children, before and after the introduction of the PCV program.

The Use of Antibiotics in the Treatment of Pediatric Varicella Patients: Evidence from the multi-country MARVEL study

Background: Varicella is a common infectious disease in childhood that can result in bacterial complications such as skin and soft tissue infections and pneumonias, among others. Although well-tolerated and effective varicella vaccines have been available for >20 years, only 40 countries around the world have implemented universal varicella vaccination (UVV) programmes. The objective of this study was to examine empiric data on the appropriate and inappropriate use of antibiotics in the treatment of pediatric varicella patients, based on data collected in five countries (Argentina, Hungary, Mexico, Peru, and Poland). Methods & Materials: Five primary data collection studies were conducted between 2014-2017 as part of MARVEL (Multi-country economic and epidemiological burden of varicella study). Detailed data were obtained on the treatment of primary varicella in both inpatients and outpatients aged 1-14 years between 2009-2016. We descriptively analyzed data on the type of complications, severity of disease (measured by number of lesions), and dosage and duration of both prescription and non-prescription antibiotic use, together with data on whether or not a confirmation of the presence of bacterial infections was available. These results were contrasted within countries to treatment guidelines for varicella and the use of antibiotics to assess appropriate and inappropriate use, and between countries to compare utilization patterns. Results: Across the 5 countries, 787 patient records were included (401 outpatients, 386 inpatients). The average number of antibiotics used per inpatient ranged from 0.9 in Poland to 1.9 in Peru, with an average duration of use of 7.2 days (Hungary) to 15.8 days (Mexico) among users. Among outpatients, this ranged from 0.03 antibiotics in Hungary to 0.4 antibiotics in Argentina, with an average duration of antibiotics used of 6.5 days (Peru) to 9.5 days (Argentina). The proportion of antibiotics prescribed without a probable or confirmed diagnosis of bacterial infection ranged from 44.3% (Hungary) to 89.9% (Peru). Conclusion: UVV could substantially reduce both inappropriate and appropriate use of antibiotics in pediatric varicella patients, and could be a valuable tool in an arsenal to combat antimicrobial resistance. Further studies on the gap between appropriate and inappropriate use of antibiotics in the treatment of varicella may be warranted.

Evaluation of the impact of immunization policies, including the addition of pharmacists as immunizers, on influenza vaccination coverage in Nova Scotia, Canada: 2006 to 2016

BackgroundInfluenza is a serious public health concern, resulting in morbidity, mortality and significant expense to healthcare systems worldwide. Annual vaccination is the most effective way to prevent influenza. The National Advisory Committee on Immunization in Canada recommends that everyone six months of age and older without contraindications should be vaccinated. The Canadian province of Nova Scotia implemented a publicly-funded universal influenza vaccination program in the 2010–2011 influenza season. In 2013, pharmacists in Nova Scotia gained the authority to provide a variety of vaccinations, including the publicly-funded influenza vaccine. This study aimed to investigate any changes in influenza vaccine coverage following the implementation of each policy change: 1) universal publicly-funded program and 2) universal publicly-funded program with the addition of pharmacists.MethodsInfluenza seasons evaluated were from 2006-2007 to 2015–2016. Coverage was estimated by examining Nova Scotia census data with aggregate immunization administration data, including the total number of vaccinations administered according to vaccine provider (physician, public health or pharmacist), geographic region, vaccine recipient age and year.ResultsThe analysis showed an increase in influenza vaccine coverage immediately following the implementation of the two studied policy changes. Vaccine coverage increased from 36.4 to 38% following the implementation of the universally funded vaccine policy. Following the implementation of pharmacists as immunizers, coverage increased from 35.7 to 41.7%. Vaccine coverage was highest in those 65 years of age and older during all years evaluated. Physicians provided the highest proportion of vaccines during all study periods, however a decreasing trend through all periods was observed. Physicians proportionately provided more vaccines in urban areas; whereas pharmacist and public health immunization providers in rural areas provided proportionately more vaccinations than their urban counterparts.ConclusionsThe addition of a universally funded vaccination policy and the addition of pharmacists as providers of the influenza vaccine resulted in increases in vaccine coverage initially. Additional research is needed to determine the long-term impacts of the policy changes on vaccination coverage and to identify other important factors affecting vaccine uptake.

Evaluation of the effect of chickenpox vaccination on shingles epidemiology using agent-based modeling.

BackgroundBiological interactions between varicella (chickenpox) and herpes zoster (shingles), two diseases caused by the varicella zoster virus (VZV), continue to be debated including the potential effect on shingles cases following the introduction of universal childhood chickenpox vaccination programs. We investigated how chickenpox vaccination in Alberta impacts the incidence and age-distribution of shingles over 75 years post-vaccination, taking into consideration a variety of plausible theories of waning and boosting of immunity.MethodsWe developed an agent-based model representing VZV disease, transmission, vaccination states and coverage, waning and boosting of immunity in a stylized geographic area, utilizing a distance-based network. We derived parameters from literature, including modeling, epidemiological, and immunology studies. We calibrated our model to the age-specific incidence of shingles and chickenpox prior to vaccination to derive optimal combinations of duration of boosting (DoB) and waning of immunity. We conducted paired simulations with and without implementing chickenpox vaccination. We computed the count and cumulative incidence rate of shingles cases at 10, 25, 50, and 75 years intervals, following introduction of vaccination, and compared the difference between runs with vaccination and without vaccination using the Mann–Whitney U-test to determine statistical significance. We carried out sensitivity analyses by increasing and lowering vaccination coverage and removing biological effect of boosting.ResultsChickenpox vaccination led to a decrease in chickenpox cases. The cumulative incidence of chickenpox had dropped from 1,254 cases per 100,000 person-years pre chickenpox vaccination to 193 cases per 100,000 person-years 10 years after the vaccine implementation. We observed an increase in the all-ages shingles cumulative incidence at 10 and 25 years post chickenpox vaccination and mixed cumulative incidence change at 50 and 75 years post-vaccination. The magnitude of change was sensitive to DoB and ranged from an increase of 22–100 per 100,000 person-years at 10 years post-vaccination for two and seven years of boosting respectively (p < 0.001). At 75 years post-vaccination, cumulative incidence ranged from a decline of 70 to an increase of 71 per 100,000 person-years for two and seven years of boosting respectively (p < 0.001). Sensitivity analyses had a minimal impact on our inferences except for removing the effect of boosting.DiscussionOur model demonstrates that over the longer time period, there will be a reduction in shingles incidence driven by the depletion of the source of shingles reactivation; however in the short to medium term some age cohorts may experience an increase in shingles incidence. Our model offers a platform to further explore the relationship between chickenpox and shingles, including analyzing the impact of different chickenpox vaccination schedules and cost-effectiveness studies.

Human papillomavirus vaccine for children and adolescents.

Human papillomavirus (HPV) is known to cause genital warts, cervical cancer, penile cancer, anal cancer and oropharyngeal cancer. In North America, the lifetime cumulative incidence of HPV infection is estimated at more than 70% for all HPV types combined. A safe and effective vaccine against nine HPV types is available. HPV vaccine should be administered routinely to all girls and boys between the ages of 9 and 13 years of age. All youth who have not received the vaccine in a routine program should receive the vaccine in a 'catch-up' program. Physicians caring for children and youth should advocate for funding and implementation of universal HPV vaccine programs.