Universal Childhood Vaccination Research Articles

Bug Breakfast in the Bulletin: Pertussis in NSW and its prevention in infants and children

Epidemiology In countries with universal childhood vaccination, epidemics of pertussis occur periodically on a background of endemic circulation, although levels of disease activity are much lower in comparison to those in unimmunised populations. In NSW and nationally, a large epidemic unfolded from 2008. In 2008–2009, the pertussis notification rate in NSW was about three times higher than the previous 5-year average. Disease activity has continued at high levels during 2010. The relatively higher rate is likely explained by both a real epidemic as well as improved diagnoses related to the wider use of molecular-based testing (polymerase chain reaction (PCR)), which is more sensitive than other available methods.

Control of hepatitis A by universal vaccination of children and adolescents: An achieved goal or a deferred appointment?

Temporal trends of Hepatitis A cases and vaccination coverage data against Hepatitis A Virus have been investigated to analyse the impact of the universal routine vaccination strategy more than 10 years from its introduction in Puglia (region of Southern Italy). The basic reproductive number ( R 0) before vaccination introduction and the effective reproductive number ( R e) after introduction have been calculated. A progressive decrease in incidence has been recorded in Puglia during last 10 years. Vaccination coverage is actually 64.8% (95% CI: 52.7–76.9%) for children aged 12–24 months and of 67.6% (95% CI: 58.4–76.8%) for 12-year-old adolescents. R 0 estimated in 1996 was 2.01; actually R e is 0.651. Theoretical age at infection is 31.82 years. Universal routine vaccination aimed at the control of direct transmission remains the milestone in the strategy for the containment of the disease in settings at an intermediate level of endemicity.

Impact of a statewide childhood vaccine program in controlling hepatitis A virus infections in Alaska

Historically, Alaska experienced cyclic hepatitis A virus (HAV) epidemics, and the HAV rate among Alaska Native people was significantly higher than among other racial/ethnic groups. We evaluated the impact of universal childhood vaccination, initiated in 1996, on HAV epidemiology in Alaska by analyzing HAV cases reported to the State of Alaska. HAV incidence in all age groups declined 98.6% from 60.0/100,000 in 1972–1995 to 0.9/100,000 in 2002–2007. The largest decrease (99.9%) was in Alaska Native people, whose incidence (0.3) in 2002–2007 was lower than the overall U.S. 2007 rate (1.0). Among age groups, the decrease (99.8%) among children aged 0–14 years was the largest. Routine childhood vaccination has nearly eliminated HAV infection in Alaska.

Acute hepatitis A

Acute hepatitis A (AHA) infection is the common cause of acute hepatitis in Korea. The incidence of symptomatic AHA has rapidly increased for the last several years especially among young adults in their twenties or thirties. Because decline seroprevalence of anti HAV with improvement of environmental hygiene. AHA shows more severe clinical manifestations with advancing years. Not only vaccination for the high risk group, also universal childhood vaccination and catch-up vaccination for young adults should be considered.

Transgenic Plant-Based Oral Vaccines

Oral vaccines offer significant advantages over needle-based vaccines for achieving universal childhood vaccination goals. The expression of vaccine antigens in transgenic plants has the potential to provide a convenient, safe approach for oral vaccination and thus a feasible alternative to traditional parenteral vaccines. Many developments in the field have ushered in improvements such as enhanced protein antigen expression for the use of plants as factories for vaccine production, and facilitated studies pertaining to immunogenicity of candidate vaccines. Oral delivery of plant-based vaccines offers the benefit of antigen protection within the harsh intestinal environment. Within the gut, mucosal immune cells are poised to respond to pathogens, but can also be exploited to elicit protective immune responses to oral vaccines. Inclusion of mucosal adjuvants during immunization with the vaccine antigen has been an important step towards the success of plant-based vaccines. This review discusses the mechanisms that control mucosal immune responses and highlights some of the studies and the results achieved following immunization with transgenic plants.

Economic evaluation of varicella vaccination in Swiss children and adolescents

This study explores the effects of three different 2-dose varicella zoster virus (VZV) vaccination strategies in Switzerland. The EVITA model was used to assess clinical benefits and costs of strategies 1) vaccination of 11-15 year old adolescents with a negative or uncertain history for chickenpox, 2) universal vaccination of toddlers at age 1 to 2 years, and 3) strategy 2 plus catch-up vaccination of 11-15 year old susceptible adolescents. The cost-effectiveness analysis compares strategies 2 and 3 versus strategy 1 (current vaccination policy in Switzerland). Probabilities for clinical outcomes and medical resource utilization were derived from a real-world survey among Swiss pediatricians and general practitioners including 236 individuals with VZV infection, published information on varicella complications, and expert opinion. Costs of medical resource utilization represent official Swiss medical tariffs. The model predicts both universal childhood vaccination strategies to be more effective in reducing varicella disease burden compared to strategy 1. Economically, both universal childhood vaccination strategies with or without catch-up result in net savings from the societal perspective reflected by a benefit cost ratio (BCR) of 1.22 or 1.29, respectively. In contrast, the model predicts net costs from the payer perspective (BCR of 0.27 and 0.30, respectively). These economic findings are comparable to those reported from other similar evaluations. However, due to the recent recommendation for using a 2-dose varicella vaccination schedule, our economic results for Switzerland are somewhat less favorable than those for other country analyses in which a less expensive 1-dose vaccination regimen for toddlers has been studied.

Support for Universal Childhood Vaccination Against Influenza Among Private Pediatric Clinics and Public Health Departments in Georgia

Recently, it has been recommended that all persons 6 months to 18 years be vaccinated annually against influenza. To assess support for this universal recommendation leading up to its implementation, a cross-sectional survey of healthcare workers at private pediatric clinics (N = 44) and public health departments (N = 75) was conducted. The survey, conducted in the state of Georgia during 2005-2006, asked about (a) support for universal childhood vaccination against influenza, (b) general and influenza-specific immunization practices in 2004-2005, and (c) types of assistance needed to implement a universal childhood recommendation. Our response rate was 70 percent for private clinics and 71 percent for public health departments. The majority of providers supported universal childhood vaccination against influenza; agreement was especially pronounced at public health departments. Public health departments employed more nurses and were more likely to have a policy of vaccinating parents along with their children; private clinics were more likely to use patient reminders or add extra hours during the influenza vaccination season. Respondents from both types of clinics indicated they would need multiple forms of assistance to implement a universal recommendation for childhood vaccination against influenza. Given the strong support for universal vaccination among healthcare workers at public health departments, these facilities may be instrumental for reaching the large number of children recently added to the recommendations. However, these facilities will need multiple forms of assistance.

Should fimbriae be included in pertussis vaccines? Studies on ELISA IgG anti‐Fim2/3 antibodies after vaccination and infection

The anti-Fim response and long-term persistence after vaccination and infection may be of importance in understanding population immunity. Longitudinal serum samples (n = 1330) from 542 non-infected children related to a Swedish vaccine trial showed that the post vaccination (DTPa5) antibody decay curve for pertussis ELISA IgG anti-fimbriae2/3 (anti-Fim2/3) was bi-phasic. A slower one followed an initial rapid decay approximately 5-6 months after the third dose at 12 months of age. After 71 months, however, 60% still had concentrations above > or =5 EU/ml, a level that had been shown to correlate with decreased risk of disease. Booster responses after re-vaccination with DTPa5 at 4, 5 and 6 years of age were strong and appeared within 1 week after vaccination, indicating immune memory. Ninety-six young children with verified pertussis infection, for whom we had serum samples both before, during and after the infection, showed a high response if they had been primed with fimbriae (either DTPa5 or DTPwc). In contrast, 76% of infected children not primed with fimbriae (a DTPa2 or DT group) only had concentrations below the minimum level of detection in all samples taken during and after the infection. In two Swedish seroepidemiological surveys, one from 1997 just after reintroduction of universal childhood vaccination against pertussis and one from 2007, the proportion of children 2-3 years with anti-Fim2/3 concentrations <5 EU/ml was similar and above 90%. This reflects that the two- or three-component pertussis vaccines (DTPa2 and DTPa3) that were introduced in Sweden in 1996 do not induce anti-Fim2/3 antibodies. In previous studies it was shown in multivariate analyses that levels of IgG anti-Fim2/3 > or =5 EU/ml reduced short-term risk of pertussis in small children. As the antibody response to Fim2/3 after infection is poor in children who have not been primed earlier in life, inclusion of immunogenic Fim2/3 in future pertussis vaccines should be considered.

Impacto da vacinação contra varicela na redução da incidência da doença em crianças e adolescentes de Florianópolis (SC)

OBJECTIVE: To evaluate the impact of universal early childhood vaccination against varicella on the reduction of its incidence in a state capital in southern Brazil. METHODS: Official epidemiologic surveillance data from the SINAN database for the 1997-2007 period were used to evaluate the impact of varicella vaccination targeting all children < 2 years of age in Florianopolis (the capital city of the state of Santa Catarina), Brazil, since 2002, thus comprising 5 years before and 6 years after the vaccination. Varicella incidence in Florianopolis was compared with the incidence in the rest of the state for four age groups (< 1, 1-4, 5-9, and 10-14 years). RESULTS: Among the 135,311 cases of varicella in the state of Santa Catarina during the 1997-2007 period, 70% were children under 10 years of age. The effectiveness of varicella vaccine ranged from 27 to 38% among the age groups but reached statistical significance only for children 1-4 years old. CONCLUSION: The vaccine was effective in reducing varicella incidence in Florianopolis for children 1-4 years old.

Impact of vaccination against varicella on the reduction of the disease incidence in children and adolescents from Florianópolis, Brazil

To evaluate the impact of universal early childhood vaccination against varicella on the reduction of its incidence in a state capital in southern Brazil. Official epidemiologic surveillance data from the SINAN database for the 1997-2007 period were used to evaluate the impact of varicella vaccination targeting all children < 2 years of age in Florianópolis (the capital city of the state of Santa Catarina), Brazil, since 2002, thus comprising 5 years before and 6 years after the vaccination. Varicella incidence in Florianópolis was compared with the incidence in the rest of the state for four age groups (< 1, 1-4, 5-9, and 10-14 years). Among the 135,311 cases of varicella in the state of Santa Catarina during the 1997-2007 period, 70% were children under 10 years of age. The effectiveness of varicella vaccine ranged from 27 to 38% among the age groups but reached statistical significance only for children 1-4 years old. The vaccine was effective in reducing varicella incidence in Florianópolis for children 1-4 years old.

Influenza vaccination rates in Ontario children: Implications for universal childhood vaccination policy

The aims of this study were to estimate influenza vaccination coverage for children during the 2006–2007 influenza season in Ontario, Canada, where universal vaccination is available, and to compare the rate among children aged 6–23 months with corresponding rates from other Canadian provinces that specifically target this high-risk group. We conducted a telephone survey of caregivers of children aged 6 months–11 years that included 4854 children from 3029 households. Ontario's vaccination rate (complete and partial coverage combined) for children aged 2–11 years was 28.3% (95% CI 26.3–30.5%) for healthy children and 36.8% (95% CI 31.4–42.5%) for those with chronic conditions. Immunization coverage of children aged 6–23 months was 24.0% (95% CI 20.6–27.7%) in Ontario, similar to Manitoba's rate of 24.1% but lower than rates in other provinces: Nova Scotia (35.5%), Quebec (41.8% for 1 year olds and 37.7% for 2 year olds during the 2005–2006 season), Saskatchewan (32.5%) and Alberta (52.2%). Universal vaccination in Ontario has achieved modest coverage in children aged 2–11 years, but has been less successful than targeted programs in vaccinating infants aged 6–23 months.

Health Benefits, Risks, and Cost-Effectiveness of Influenza Vaccination in Children

Annual vaccination of all children 6-59 months of age is recommended in the United States but not in most of Europe. This paper reviews issues surrounding the epidemiology of influenza and vaccine effectiveness relevant to the determination of vaccination policy. Most clinical trials of vaccines (and treatments) that provide the evidence for current policy took place in the 1990s when rates of influenza-like illness (ILI) were twice those reported in recent years. The impact of influenza in the community is concealed by the variety of diagnoses appropriate to describing acute respiratory infections. Even in influenza virus active periods diagnoses of coryza, acute bronchitis, and otitis media made by general practitioners greatly exceed those of ILI. Respiratory syncytial virus presents particular problems because it often circulates at the same time as influenza. Thus, the diagnostic uncertainty and variety of respiratory pathogens causing similar illnesses are major confounders when estimating influenza vaccine effectiveness. Although meta-analyses have cast doubt on the wisdom of the universal vaccination of children, high-quality clinical trials have demonstrated efficacy against laboratory-confirmed infection. The distinction between this positive benefit and the wider issue of effectiveness against ILI in the community poses difficulties for determining policy. Mathematical models examining this issue are populated with data that are mostly estimated: therefore, the sensitivity analysis is critical and the conclusions are invariably accompanied by reservations. National policies based on demonstrated cost effectiveness are desirable, but these should not become a barrier to parents wishing to secure a benefit for their child or family, provided there is clear evidence of clinical efficacy.

Private Pediatric Clinic Characteristics Associated with Influenza Immunization Efforts in the State of Georgia: A Pilot Evaluation.

The Advisory Committee on Immunization Practices (ACIP) recently recommended that all children 6 months to 18 years be vaccinated annually against influenza. Because pediatricians will be critical for implementing this recommendation, we assessed the characteristics of immunization providers associated with the greatest efforts to vaccinate children against influenza. Using a cross-sectional survey of 35 private pediatric clinics in Georgia, we found that adding extra hours for immunization during the influenza vaccination season and having a policy of allowing six or more vaccines to be delivered at one appointment were characteristics associated with a greater intent to vaccinate children in the 2004-2005 influenza vaccination season. Most respondents indicated that for their clinic to implement a universal childhood vaccination policy it would be important to have a formal recommendation from the ACIP and American Academy of Pediatrics, and to be assured that they could receive credits or refunds for unused vaccine.

Hepatitis B Virus Vaccine: The Nigerian Story

Hepatitis B (HBV) virus in endemic in Nigeria. Infection is acquired mainly in childhood through horizontal transmission. The infection is preventable by vaccination. Universal childhood vaccination against the infection started in Nigeria less than ten years. Hepatitis B vaccine coverage in Nigeria is 41%, though now it has increased over the last few years. An example of community based privately financed vaccination project is given where HBV coverage rate is 58% and the vaccine efficacy against infection is 80%. IFEMED Journal Vol. 14 (1) 2008: pp. 4-5

Cost-effectiveness analysis of universal childhood vaccination against varicella in Brazil

This study conducts a cost-effectiveness analysis of a childhood universal varicella vaccination program in Brazil. An age and time-dependent dynamic model was developed to estimate the incidence of varicella for 30 years. Assuming a single-dose schedule; vaccine efficacy of 85% and coverage of 80%, the program could prevent 74,422,058 cases and 2905 deaths. It would cost R$ 3,178,396,110 and save R$ 660,076,410 to the society and R$ 365,602,305 to the healthcare system. The program is cost-effective (R$ 14,749 and R$ 16,582 per life-year saved under the societal and the healthcare system's perspective, respectively). The program's cost-effectiveness is highly sensitive to the vaccine price and number of doses.

A cost-effectiveness analysis of universal childhood hepatitis A vaccination in China

The socioeconomic improvement has impacted hepatitis A virus (HAV) infection with a shift from high to intermediate endemicity in many parts of China. The first China-developed inactivated hepatitis A vaccine, with significantly low price, was licensed in 2002, prompting us to evaluate whether universal childhood vaccination is advisable now in China. We considered vaccination scheduled at ages 12 and 18 months for all healthy children, and assumed that a single cohort was enrolled in 2005. A Markov model was used to predict hepatitis A outcomes and costs. Vaccination was compared with no vaccination, and the cost-effectiveness of vaccination was evaluated from the health system and the societal perspectives. The analysis was run separately in five regions (covering all the 31 provinces of Mainland China) defined by anti-HAV prevalence (around 50%, 50–69%, 70–79%, 80–89% and 90%–). The study projects that with the Chinese low-cost vaccine, vaccination could gain quality adjusted life years (QALYs) through the whole country and save health system or societal costs in the lowest, lower, intermediate and higher infection regions. Vaccination should also be cost-effective in the highest infection region because of low additional costs per QALY gained. However, vaccination would increase the probability of death due to hepatitis A in the highest and higher infection regions by 38 and 37 per million enrolled, respectively, and as vaccine protection loss increases the risk would also occur in intermediate and lower infection regions. The trend that the lower infection level the region has, the more cost-effective vaccination would be is obvious. Sensitivity analyses prove that our conclusions are robust. Considering the potential risk of vaccination, as well as unbalanced socioeconomic developments and significant differences in HAV infection through the whole country, the study suggests that universal childhood hepatitis A vaccination should be first administrated in provinces with the lowest infection level. With knowledge accumulation and further evaluations, the zone of immunization would be considered to be expanded gradually from provinces with lower infection level to those with higher.

Universal vaccination of children against hepatitis a in Chile: a cost-effectiveness study

To evaluate the healthcare and economic impact of routine hepatitis A vaccination of toddlers in Chile. We used a dynamic model of hepatitis A infection to evaluate the impact of a two-dose vaccination program, administered at ages 12 and 18 months. The model incorporated the changing epidemiology of hepatitis A in Chile and the development of vaccine-induced herd immunity. Our analysis was conducted from the public payer perspective, and an estimation of the societal perspective was performed. Costs are expressed in 2005 U.S. dollars. Vaccination of toddlers rapidly reduced the healthcare burden of hepatitis A. In the base case (95% vaccination coverage, 100-year time horizon, 1% annual decrease in force of infection), the average number of infections fell by 76.6% annually, and associated deaths fell by 59.7%. Even at 50% coverage, the program reduced infection rates substantially. Routine vaccination of toddlers had economic as well as health benefits, saving $4,984 per life-year gained (base case scenario). The program became cost saving after 6 years, and its overall cost-effectiveness per life-year gained was largely unaffected by changes in disease-related costs, herd immunity, coverage rate, and annual decrease in force of infection. Routine vaccination of toddlers will reduce the rates of symptomatic hepatitis A and associated mortality. The two-dose schedule evaluated here will be less expensive than disease-related costs in the absence of vaccination from the sixth year of its implementation. These findings support the establishment of a routine vaccination program for toddlers in Chile.

Public Health Dilemmas Concerning a 2-year old Hepatitis-B Carrier – Response

The public health physician is concerned about the possibility that, at a nursery, this boy would have close contact with other children and might infect them with hepatitis B virus (HBV). HBV infection in children is often asymptomatic, and acute disease with severe complications is rare. However, children often become chronic carriers after infection, which may lead to cirrhosis and liver cancer. HBV carriers also remain life long sources of infection to others and hence contribute to the spread of disease. HBV is mainly spread via blood and semen. Transmission through saliva, though unlikely, is certainly possible, especially where the boy shows a high HBV viremia [1]. The risk of transmission in day care is low, but has been reported and confirmed by genotyping [2–6]. The theoretical routes of transmission are direct through small wounds and, more important, by child bites. Indirect transmission is also possible through the sharing of utensils including toothbrushes, and, to a lesser extent, the sharing of toys that children may put in their mouth. Only very few countries with low incidence and prevalence of HBV infection, have not yet included hepatitis B in their universal childhood vaccination program. Universal vaccination prevents (most) day care transmission. This case occurred in TheNetherlands, and as The Netherlands does not have a universal HBVvaccination program, one could assume that most of the children in this nursery would be susceptible to HBV infection. However, there seems to be no scientific consensus that the vaccine does offer full protection against the G145R-HBV-mutant. While animal studies suggest that the vaccine does protect against this mutant [7] there remains ongoing uncertainty regarding the effectiveness of the vaccine [8]. The case description presents several policy options: preventing the child from attending the nursery; allowing him to go but with strict hygienic measures at the nursery; and offering vaccination to all other children at the nursery. All these possibilities may be detrimental to the child’s welfare because he will be treated differently by care-givers and other parents. And even if day care staff and other parents are not informed which child is the source of risk, it may be difficult to keep it a secret. This would be more so if care-givers are informed and subsequently are more attentive to possible risk-contacts of the boy. Other parents may find out about the identity of the child and try to avoid contact between him and their own children. Moreover, the theoretical possibility that this child may be infected with a virus against which there is less protection could easily lead them to overestimate the risks of infection. Bioethical Inquiry (2008) 5:87–89 DOI 10.1007/s11673-008-9088-3

Financing Immunization of Adults in the United States

Immunization is one of the most effective and cost-effective prevention measures available. As a result of universal vaccination of children, polio has been eliminated in the United States and much of the world, measles and rubella are no longer endemic diseases in the United States, and most of the other vaccine-preventable diseases of childhood are at or near record lows. A recent review of clinical preventive services by Partnership for Prevention gave childhood immunization a perfect score of 10, based on clinically preventable burden and cost-effectiveness.

Rubella vaccination strategy

Whenrubellavaccineswereintroducedin1969theywereinitiallyusedonlyinindustrializedcountries.Twomajorstrat-egies were used to prevent the occurrence of congenitalrubella syndrome (CRS). In the UnitedStates, the strategy aimed to interruptrubellaviruscirculationamongyoungchil-dren, thereby reducing the possibility ofexposure of a susceptible pregnantwoman. This was accomplished by massvaccinationofchildrenaged1-12(overthecourse of 1-3 years) followed by universalvaccination of children as they reached 1year of age. In the United Kingdom (UK),the approach was to provide individual protection to girls astheyenteredthechildbearingageandthisinvolvedvaccinat-ing girls (only) at 12-14 years of age.The U.S. approach greatly reduced the overall incidenceofrubellaandCRSandeliminatedtheprior6-9yearepidemiccycleofthedisease,butsporadiccasesofCRScontinuedwithtransmission among young adults. In the UK, there was littlechange in the secular trend of rubella occurrence and therewere sizeable epidemics with substantial increases in thenumber of cases of CRS, although fewer than in the pre-vaccine era. Thus, both approaches had some success, butneither had optimum impact. Reviewing the experience, in1983, we concluded that the first priority of rubella vaccina-tion programs should be to vaccinate women of childbearingage. The second priority should be to interrupt transmissionofrubella(byvaccinatingchildren).This“complete”strategyshould lead to maximal prevention of CRS.