Varicella vaccination in Italy and Germany – different routes to success: a systematic review

Effectiveness of the combined MMRV Priorix-Tetra™ vaccine against varicella in a large Italian region: A case-control study

Priorix-Tetra™ (MMRV GlaxoSmithKline Biologicals' vaccine) was developed based on the existing measles-mumps-rubella and varicella vaccines. In this study, we aimed to estimate the effectiveness of the combined measles-mumps-rubella-varicella Priorix-Tetra™ vaccine against varicella in real-world conditions. We conducted a post-marketing retrospective case-control study in the Apulia region of Italy in children aged 1-9 years born between January 1, 2008 and December 31, 2016. We assessed the effectiveness against varicella of all grades of severity (including hospitalisation) and against hospitalisation for varicella of a single and two doses of Priorix-Tetra™. Moreover, we also assessed effectiveness of monovalent varicella (monovalent-V) vaccine and any varicella vaccines. Vaccine effectiveness was calculated as (1-OR) x 100. We introduced demographic variables in the model to adjust Vaccine effectiveness (aVE) by potential confounders (sex and year of birth). We recorded 625 varicella cases and matched them with 1,875 controls. Among 625 cases, 198 had received a single MMRV dose, 10 two MMRV doses, 46 a single monovalent-V dose, none two monovalent-V doses; four a monovalent-V as first dose and MMRV as second dose, and one a MMRV as first dose and monovalent-V as second dose; 366 cases were not vaccinated. The aVE against varicella of all grades of severity was 77.0% and 93.0% after a single dose and after two doses of MMRV, respectively. The aVE against varicella of all grades was 72.0% after a single dose of monovalent-V vaccine. The aVE against varicella of all grades of severity was 76.0% after a single dose and 94.0% after two doses of any varicella vaccine. The aVE against varicella hospitalisation was 96% after a single dose of any varicella vaccine. Priorix-Tetra™ showed to be an effective vaccine and the two-dose schedule should be recommended to optimise immunisation programmes. A single dose was able to provide protection against varicella hospitalisation.

Decline in varicella cases contacting primary health care after introduction of varicella vaccination in Finland - A population-based register study

A two-dose varicella vaccination programme at the age of 18 months and 6 years started in September 2017 in Finland with catch-up vaccinations, based on earlier modelling results, for children <12 years (born in 2006 or later) with no history of varicella. Nationwide population-based register data were used to assess the age-specific vaccination coverage and the annual incidence rates of varicella cases contacting public primary health care in 2014-2020. Age-specific incidence rates after (2022) and before (2014-2016) the implementation of the vaccination programme was compared by incidence rate ratios (IRR) with 95 % confidence interval. In 2019-2022, the first-dose coverage of varicella vaccination among children following the routine vaccination programme ranged from 85 to 87 % (children born in 2016 or later). The second-dose coverage was 58 % for the children born in 2016. The coverage of the catch-up vaccinations ranged from 18 % (children born in 2006) to 82 % (children born in 2015) for the first dose and from 10 % to 64 % for the second dose in the respective birth cohorts. In 2022, compared to the pre-vaccination period (2014-2016) the annual incidence rate of varicella cases contacting public primary health care declined in all age groups. The reduction ranged from 92 % to 98 % among the children eligible for the vaccinations (born 2006 or later). The 87 % reduction in the incidence rate among the unvaccinated children < 1 year suggests the indirect effect of the vaccinations. Introducing varicella vaccinations with catch-up was associated with rapid reduction in the varicella cases contacting primary health care in all ages. However, the coverage of the routine programme needs to be improved further as presently susceptibles accumulate and enable thus further outbreaks in coming decades.

Understanding Factors Contributing to Vaccine Hesitancy in a Large Metropolitan Area

Vaccine hesitancy has become a major global concern, leading to a significant decrease in the vaccination rate, with the World Health Organization recognizing it as one of the top ten threats to public health. Moreover, the health cost generated is evaluated to be 27 billion dollars per year in the US alone. To investigate the association between demographic variables and knowledge, attitudes, and behaviours related to vaccination, a survey-based cross-sectional study was conducted with 1163 individuals. Three models were used to perform a multiple linear regression analysis. In Model I, knowledge about vaccinations was found to be associated with smoking habits, education, and marital status. In Model II, attitudes towards vaccinations were significantly associated with sex, smoking habits, education, marital status, and knowledge. In Model III, behaviours related to vaccination were associated with sex, smoking habits, having children, knowledge, and attitudes. One potential solution to improve behaviours related to vaccinations in the general population is to implement specific public health programs, which can be a cost-effective intervention. This study provides valuable insights into the determinants of knowledge, attitudes, and behaviours related to vaccinations in the general population.

Safety of varicella vaccination strategies: An overview of reviews

The safety of new vaccines under development as well as existing vaccines is a key priority for national and international public health agencies. A number of countries have implemented universal childhood varicella vaccination programmes over the past 30 years. However, strategies differ in terms of the number of doses, type of vaccine(s) recommended, age at vaccination and interval between doses for a two-dose schedule. An overview of reviews was undertaken to assess the existing systematic review evidence of the safety of varicella vaccination strategies. The review was restricted to immunocompetent children aged 9 months to 6 years inclusive. A comprehensive search of databases, registries and grey literature was conducted up to 2 February 2022. Two reviewers independently screened, extracted data and assessed the methodological quality of included reviews. Overlap of included reviews was also assessed. A total of 17 reviews, incorporating both the monovalent varicella only and quadrivalent measles-mumps-rubella-varicella (MMRV) vaccines were included in the overview; six assessed the safety of one-dose strategies, four assessed the safety of two-dose strategies and 14 reviews did not specify the dosing strategy. The evidence suggests that mild local and systemic reactions are relatively common with varicella vaccination. Febrile seizures are also possible adverse effects of both the monovalent and quadrivalent MMRV vaccine, but serious adverse reactions are rare. While most reviews contained methodological flaws, and analysis by vaccine type and dosing strategy was restricted due to lack of detail in reporting of the reviews, there was clear and consistent evidence from a substantial evidence base, comprising 34 randomised controlled trials and 62 other primary studies/reviews, that varicella vaccination is safe.

Sero-Epidemiological Study of Varicella in the Italian General Population

The aim of this study was to analyze the seroprevalence of varicella in Italy and to evaluate the impact of varicella vaccination, which has been mandatory for newborns since 2017. The levels of VZV-specific IgG antibodies were determined by the ELISA method in residual serum samples obtained from subjects aged between 6 and 64 years and residing in 13 Italian regions. Overall, 3746 serum samples were collected in the years 2019 and 2020. The overall seroprevalence was 91.6% (89.9% in males and 93.3% in females; p = 0.0002). Seroprevalence showed an increasing trend (p < 0.0001) starting in the younger age groups: 6-9 years: 84.1%; 10-14 years: 88.7%; 15-19 years: 89.3%; 20-39 years: 93.1% and >40 years: 97.0%. The seroprevalence data obtained in the present study were compared with those relating to previous sero-epidemiological surveys conducted, respectively, in the years 1996-1997, 2003-2004 and 2013-2014, taking into consideration only data from regions monitored in all surveillance campaigns. The comparison highlighted for the period 2019-2020 showed significantly higher values in the age groups 6-9 (p < 0.001), 10-14 (p = 0.018) and 15-19 years (p = 0.035), while in adults, the trend did not change over time (ns). These results highlight the positive impact of varicella vaccination in Italy.

Systematic review of economic evaluations of varicella vaccination programmes

OBJECTIVES

This study carried out a systematic literature review of economic evaluations of varicella vaccination programmes from the earliest publication to the present day, including programmes in the workplace and in special risk groups as well as universal childhood vaccination and catch up programmes.

METHODS

Articles published from 1985 until 2022 were sourced from PubMed/Medline, Embase, Web of Science, NHSEED and Econlit. Eligible economic evaluations, which included posters and conference abstracts, were identified by two reviewers who scrutinised each other's selections at both title and abstract and full report stages. The studies are described in terms of their methodological characteristics. Their results are aggregated by type of vaccination programme and the nature of the economic outcome.

RESULTS

A total of 2575 articles were identified of which 79 qualified as economic evaluations. A total of 55 studies focused on universal childhood vaccination, 10 on the workplace and 14 on high risk groups. Twenty-seven studies reported estimates of incremental cost per quality-adjusted life year (QALY) gained, 16 reported benefit-cost ratios, 20 reported cost-effectiveness outcomes in terms of incremental cost per event or life saved and 16 reported cost-cost offset results. Most studies of universal childhood vaccination reported an increase in overall costs to health services, but often a reduction in cost from a societal perspective.

CONCLUSIONS

The evidence surrounding the cost-effectiveness of varicella vaccination programmes remains sparse with contrasting conclusions in some areas. Future research should particularly aim to encompass the impact of universal childhood vaccination programmes on herpes zoster among adults.

Clinical efficacy and effectiveness of alternative varicella vaccination strategies: An overview of reviews

A number of countries have implemented universal childhood varicella vaccination programmes over the past 30 years. However, strategies differ in terms of dosing schedule (one- or two-dose), type of vaccine(s) recommended (monovalent, quadrivalent measles-mumps-rubella-varicella, or both), age at vaccination, and dosing interval for a two-dose schedule. An overview of reviews was undertaken to assess the existing systematic review evidence of the clinical efficacy/effectiveness of alternative varicella vaccination strategies. A comprehensive search of databases, registries and grey literature was conducted up to 2 February 2022. Two reviewers independently screened, extracted data and assessed the methodological quality of included reviews. A total of 20 reviews were included in the overview; 17 assessed the efficacy/effectiveness of one-dose strategies and 10 assessed the efficacy/effectiveness of two-dose strategies. Although the quality of most reviews was deemed 'critically low', there was clear and consistent evidence that vaccination is very effective at reducing varicella. While the analysis was restricted due to lack of detail in reporting of the reviews, the evidence suggests that two-dose strategies are more efficacious/effective than one-dose strategies in preventing varicella of any severity, but that both strategies have similar high efficacy/effectiveness in preventing moderate or severe varicella. Based on this evidence in this overview of reviews, a key consideration for policymakers on the possible introduction of a childhood varicella vaccination programme and the choice between a one- or two-dose strategy, will be whether the objective of a programme is to prevent varicella of any severity or to prevent moderate to severe varicella.

Varicella outbreaks in schools and kindergartens in Shanghai, China from 2011 to 2020

Background

Varicella is a contagious disease caused by varicella-zoster virus and varicella vaccine (VarV) is the most effective way to prevent and control varicella. Despite high VarV coverage there were still varicella outbreaks in schools and kindergartens. We aim to analyze the epidemiological characteristics of varicella outbreaks in Huangpu District, Shanghai, China from 2011 to 2020.

Methods

For varicella outbreaks, case information and vaccination history were collected. Mann–Kendall test and descriptive methods were used to analyzed the trend and epidemiological catachrestic of varicella outbreaks.

Results

A total of 57 varicella outbreaks were reported from 2011 to 2020, including 30 outbreaks (52.6%) in primary schools. The results of the Mann–Kendall trend test (z = 1.97, p = 0.049) showed an upward trend in the number of cases during the study period, but the trend change was not statistically significant. Emergency vaccination was carried out in 42 (73.7%) outbreaks which influenced the duration of the epidemic (F = 4.53, p = 0.0379). A total of 573 varicella cases were reported, including 357 cases (62.3%) who had received at least one dose of varicella vaccine.

Conclusions

The number of varicella outbreaks has not changed significantly in the decade from 2011 to 2020. The strategy of varicella vaccination, the development and application of varicella vaccine, and the control measures after the occurrence of varicella outbreaks need to be optimized. In addition to vaccination, as a disease transmitted by contact, quarantine measures, good personal hygiene, environmental disinfection, and ventilation are also important.

Pediatric Hospitalization for Varicella in an Italian Pediatric Hospital: How Much Does It Cost?

BACKGROUND

Varicella is a common pediatric infection. Even if it generally has a benign course, it may complicate and require hospitalization. The aim of our study was to estimate the acute hospitalization cost (AHC) for varicella in the acute phase in a pediatric population.

METHODS

We calculated the AHC of pediatric patients admitted for varicella at Bambino Gesù Children Hospital, Rome, Italy, from 1 November 2005 to 1 November 2020.

RESULTS

In the study period, 825 pediatric patients affected by varicella were hospitalized. The mean hospitalization cost was EUR 4015.35 (range from EUR 558.44 to EUR 42,608.00). Among patients, 55% were unvaccinable due to either their age or their immunosuppression status. They would benefit from herd immunity, reducing the overall AHC by EUR 182,196,506. Since the introduction of the compulsory vaccination against varicella in Italy, we observed a significant reduction in AHC cost of 60.6% in 2019 and of 93.5% in 2020. Finally, from the beginning of the COVID-19 pandemic, we documented a decline of 81.2% and 76.9% in varicella hospitalization, compared to 2018 and 2019, respectively.

CONCLUSIONS

Varicella AHC is an important economic and health assessment point and can be useful for improving preventive strategies.

Current understandings of the impact of mandatory vaccination laws in Europe

Vaccinations are among the most successful preventive tools to protect collective health. In response to alarming vaccines preventable diseases (VPDs) outbreaks resurgence, decreased vaccination coverage and vaccine refusal, several European countries have recently revised their vaccination policies introducing or extending mandatory vaccinations. This review examines the health, political and ethical aspects of mandatory vaccination.The authors first clarify terms and definitions and propose a conceptual framework of mandatory policies. Second, they describe the current status of mandatory childhood immunization programmes in Europe, assessing selected mandatory laws. Third, as the authors conduct a systematic review of the literature (retrieving from Medline 17 relevant records between 2010 and 2020), they take an analytical approach to measure the impact of mandatory vaccination policies on both VPDs control and immunization coverage, but also on population attitudes toward vaccines. 40% of European countries currently have mandatory vaccination policies; however, policies vary widely and, although there is evidence of increased vaccine uptake, their impact on informed adherence to preventive behaviors is scant.Although mandatory vaccination policies might be needed to protect collective health in times of emergency, public health goals of VPD prevention and health promotion should primarily be pursued through health education and population empowerment.

A Study of Varicella Seroprevalence in a Pediatric and Adolescent Population in Florence (Italy). Natural Infection and Vaccination-Acquired Immunization

Background: Varicella is a well-known infectious disease that can have severe complications, also in young children. The Universal Varicella Vaccination (UVV) program was introduced in Tuscany (Italy) in 2003, with a two-dose vaccine schedule given to children between their 13th and 15th month, and at 5–6 years old, as a monovalent for varicella (V) or tetravalent (measles, mumps, rubella and varicella (MMRV)) formulation. Although varicella notifications have dramatically fallen in the last two decades, varicella disease underreporting remains a challenge. Methods: A qualitative immunoenzymatic test (ELISA) was used to measure the presence of anti-varicella antibodies in 165 sera of subjects aged 1–18 years residing in the province of Florence (Italy). Information regarding the anamnestic and vaccination status (including disease notification) was also collected. Results: Our study showed an overall varicella seropositivity of 75.8% (reaching the maximum at 96.3% in the 15–18 years age group). We found that varicella disease notification had been recorded for only 7/165 subjects; however, since 42/165 recalled having had the disease, we can hypothesize that some of them must have been underreported. Furthermore, our study showed that the presence of antibodies after the varicella vaccination remained over time, lasting up to 12 years. Conclusions: Although varicella seroprevalence is <95% in almost all our age groups (except for the 15–18 years age group), our data are encouraging and reflect the success of the introduction of the UVV program and the vaccination campaigns promoted in the Tuscany region.

Changes in epidemiological features of vaccine preventable infectious diseases among three eras of national vaccination strategies from 1953 to 2018 in Shanghai, China

Background

Recurring outbreaks of infectious diseases highlight the importance of population vaccination strategies. We aimed to assess the impact of national vaccination strategies on vaccine-preventable infectious diseases (VPDs) in Shanghai, China and to identify vulnerable groups that may benefit from future vaccination policies.

Methods

Infectious disease data from 1953 to 2018 was obtained from Xuhui District Center for Disease Control and Prevention, Shanghai China. We used joinpoint regression to show incidence, mortality and fatality trends and to determine annual percent change in incidence of 12 VPDs among three eras of national immunization strategies: (1)1953–1977, (2)1978–2007, and(3)2008–2018.

Findings

Incidence, mortality, and fatality from VPDs have decreased drastically over the three eras, despite the inclusion of more diseases over time. Strikingly, the overall yearly incidence of VPDs shows an increasing trend from 2000 to 2018 in Shanghai (annual percentage changes, APC:7.7, p = 0.025). In the third era (2008–2018), the three VPDs with the highest incidence were varicella (80.2 cases/100,000), hand, foot, and mouth disease (HFMD) (73.6 cases/100,000), and hepatitis (43.5 cases/100,000). A significant upward trend was also observed in hepatitis (APC:24.9, p<0.001), varicella (APC:5.9, p = 0.006), and HFMD (APC:11.8, p = 0.003) from 2008–2018. Hepatitis and tuberculosis are the only VPDs with fatality cases in this period.

Interpretation

Focus is needed in controlling adult hepatitis and tuberculosis, either by introducing adult booster vaccines or by research into more effective vaccines. Varicella and HFMD are on the rise, but vaccines for these are not included in national programs. Strategies funded by government agencies or encouraged by research incentives are needed for varicella and HFMD, such as two-dose and novel multi-valent vaccines, respectively.

Funding

Chinese Ministry of Education, Shanghai Municipal Government.