Is annual vaccination best? A modelling study of influenza vaccination strategies in children

IntroductionAnnual vaccination of children against influenza is a key component of vaccination programs in many countries. However, past infection and vaccination may affect an individual’s susceptibility to infection. Little research has evaluated whether annual vaccination is the best strategy. Using the United Kingdom as our motivating example, we developed a framework to assess the impact of different childhood vaccination strategies, specifically annual and biennial (every other year), on attack rate and expected number of infections.Methods and findingsWe present a multi-annual, individual-based, stochastic, force of infection model that accounts for individual exposure histories and disease/vaccine dynamics influencing susceptibility. We simulate birth cohorts that experience yearly influenza epidemics and follow them until age 18 to determine attack rates and the number of infections during childhood. We perform simulations under baseline conditions, with an assumed vaccination coverage of 44%, to compare annual vaccination to no and biennial vaccination. We relax our baseline assumptions to explore how our model assumptions impact vaccination program performance.At baseline, we observed less than half the number of infections between the ages 2 and 10 under annual vaccination in children who had been vaccinated at least half the time compared to no vaccination. When averaged over all ages 0–18, the number of infections under annual vaccination was 2.07 (2.06, 2.08) compared to 2.63 (2.62, 2.64) under no vaccination, and 2.38 (2.37, 2.40) under biennial vaccination. When we introduced a penalty for repeated exposures, we observed a decrease in the difference in infections between the vaccination strategies. Specifically, the difference in childhood infections under biennial compared to annual vaccination decreased from 0.31 to 0.04 as exposure penalty increased.ConclusionOur results indicate that while annual vaccination averts more childhood infections than biennial vaccination, this difference is small. Our work confirms the value of annual vaccination in children, even with modest vaccination coverage, but also shows that similar benefits of vaccination may be obtained by implementing a biennial vaccination program.Author summaryMany countries include annual vaccination of children against influenza in their vaccination programs. In the United Kingdom (UK), annual vaccination of children aged of 2 to 10 against influenza is recommended. However, little research has evaluated whether annual vaccination is the best strategy, while accounting for how past infection and vaccination may affect an individual’s susceptibility to infection in the current influenza season. Prior work has suggested that there may be a negative effect of repeated vaccination. In this work we developed a stochastic, individual-based model to assess the impact of repeated vaccination strategies on childhood infections. Specifically, we first compare annual vaccination to no vaccination and then annual vaccination to biennial (every other year) vaccination. We use the UK as our motivating example. We found that an annual vaccination strategy resulted in the fewest childhood infections, followed by biennial vaccination. The difference in number of childhood infections between the different vaccination strategies decreased when we introduced a penalty for repeated exposures. Our work confirms the value of annual vaccination in children, but also shows that similar benefits of vaccination can be obtained by implementing a biennial vaccination program, particularly when there is a negative effect of repeated vaccinations.     

Parent perceptions of dentists’ role in HPV vaccination

IntroductionOffering HPV vaccine in settings beyond the traditional medical home holds promise for increasing the currently low levels of coverage. As adolescents frequently visit dentists, dental practices may be one such alternative vaccination setting. This study assessed parent attitudes about the roles dental providers could play in HPV prevention, including vaccine provision.MethodsIn September 2016, we conducted an online survey using a national sample (n = 1209) of U.S. parents of adolescent children aged 11–17. Adolescents’ mean age was 14; 53% were male and 62% were non-Hispanic white. We identified correlates of parents’ comfort with dentists as HPV vaccinators using multivariable logistic regression.ResultsOverall, 23% of parents reported that they would feel comfortable with their child receiving HPV vaccine from a dentist. In multivariable analyses, parents had greater odds of being comfortable if they had higher trust in their child’s primary care provider (OR = 1.27, 95% CI: 0.96–1.68) and lower odds if their child was female (OR = 0.65, 95% CI: 0.50–0.86). Convenience (20%) and oral health expertise (20%) were the most commonly cited benefits of dentists administering the vaccine. Wanting their child’s regular provider to administer and track vaccinations (61% and 58%, respectively), and lack of insurance coverage (30%) were the most commonly cited concerns. Parents expressed somewhat greater comfort with roles dentists might play in promoting HPV vaccination other than vaccine delivery, such as providing education.ConclusionsParents in this sample had low comfort with dentists as HPV vaccinators. Findings from this study highlight potential concerns to be addressed before dental practices consider offering HPV vaccination in the future. Further research should assess dentists’ perspectives and explore alternative roles for dental providers in HPV prevention efforts.     

Cost–benefit of the introduction of new strategies for vaccination against pertussis in Spain: Cocooning and pregnant vaccination strategies

BackgroundPertussis remains a public health problem in countries with high vaccination coverage. Classic vaccination approaches have failed to effectively control the infection. The incidence of pertussis hospitalizations in infants is high, especially in those younger than 3 months who are in high risk of a severe disease and death. Additional strategies are recommended for short-term protection of this vulnerable population. In this study, we estimated the impact of 2 strategies for pertussis prevention in infants younger than 1 year of age—a cocoon vaccination strategy and the vaccination of pregnant women (VPW)—and the cost–benefit of these approaches relative to the current vaccination policy in Spain.MethodsA cost–benefit analysis was conducted from the perspective of the publically-funded Spanish healthcare system, based on the yearly number of hospitalizations during the period of 2009 to 2011. We calculated the absolute risk reduction, the number of parents that would need to be vaccinated to prevent 1 hospitalization or death in infants <1 year, and the net benefit-to-cost ratio of each strategy.ResultsFrom 2009 to 2011, the incidence of pertussis in Spain was 153.44 hospitalizations per 100,000 infants <1 year. The absolute risk reduction for hospitalization would be 42.1/100,000 with cocooning and 75.2/100,000 with VPW. The number of parents needed to vaccinate with the cocoon strategy to prevent 1 pertussis hospitalization would be 4752 and to prevent 1 death, more than 900,000. With VPW, 1331 pregnant women would have to be vaccinated to prevent 1 hospitalization and 200,000 to prevent 1 death. The benefit-to-cost ratio was 0.04 for cocooning and 0.15 for VPW.     

Effect of media use on mothers’ vaccination of their children in sub-Saharan Africa

While several studies have examined the crucial role that parents’ vaccination behaviors play in reducing disease spread and severity among children, few have evaluated the connection between parents’ media use and their decision on whether or not to vaccinate their child, specifically in relation to the BCG (Bacillus Calmetter Guerin), DPT (Diptheria, Pertussis, Tetanus) polio, and measles vaccines. Media channels are a critical source of health information for parents, which is especially true in Sub-Saharan Africa, as there is often a dearth of local healthcare providers. The aim of this paper is to investigate the role that media use plays in a mothers’ choice to vaccinate their infant children in sub-Saharan Africa, specifically focusing on whether media use is associated with socioeconomic status (SES) and a mothers’ vaccination of their children. Cross-sectional data from the Demographic Health Surveys of 13 sub-Saharan countries (2004–2010) were pooled. A multivariate Poisson regression of 151,209 women was used to calculate adjusted relative ratios and 95% confidence intervals for the associations among SES, media use, and immunization. Education and wealth were found to be strongly and positively associated with vaccine-uptake behaviors. The effects of media use (radio and television) were found to be associated with the relationships between SES and vaccine uptake. However, it did not reduce the impact of SES on vaccination. These findings indicate that mass media may be an important tool for future efforts to reduce the health discrepancies between children from high- and low-socioeconomic backgrounds. Going forward, immunization strategies should include communication plans that will address and mitigate potential immunization disparities among parents of different SES backgrounds.     

Did the temporary suspension of Vaxzveria vaccinations influence COVID-19 vaccination intentions,vaccination perceptions and trust in the vaccination campaign? A repeated survey study in the Netherlands

In spring 2021, several countries, among which the Netherlands, suspended vaccinations against COVID-19 with the Vaxzevria vaccine from AstraZeneca after reports of rare but severe adverse events. This study investigates the influence of this suspension on the Dutch public’s perceptions of COVID-19 vaccinations, trust in the government’s vaccination campaign, and COVID-19 vaccination intentions. We conducted two surveys in a population of general Dutch public (18 + ), one shortly before the pause of AstraZeneca vaccinations and one shortly thereafter (N eligible for analysis = 2628). Our results suggest no changes in perceptions nor intentions regarding the COVID-19 vaccines in general but do suggest a decline in trust in the government’s vaccination campaign. In addition, after the suspension, perceptions of the AstraZeneca vaccines were more negative in comparison to those of COVID-19 vaccinations in general. AstraZeneca vaccination intentions were also considerably lower. These results stress the need to adapt vaccination policies to anticipated public perceptions and responses following a vaccine safety scare, as well as the importance of informing citizens about the possibility of very rare adverse events prior to the introduction of novel vaccines.     

Decline of varicella vaccination in German surveillance regions after recommendation of separate first-dose vaccination for varicella and measles–mumps–rubella

Background

Germany introduced routine varicella (V) vaccination in 2004. Due to a slightly increased risk of febrile convulsions after first-dose application of combined measles–mumps–rubella–varicella (MMRV) vaccine separate first-dose vaccinations with MMR and monovalent V vaccine were recommended in September 2011.

Methods

We compared V and MMR vaccinations in paediatric practices from two surveillance regions (Munich and Würzburg) one year before and after the change in the recommendation.

Results

A total of 1405/326 monthly reports were provided by a monthly average of 79/14 practices participating in Munich/Würzburg. V first-dose vaccinations (monovalent V or MMRV vaccine) declined by 12% in Munich (from 10.1 to 8.9 vaccinations per month and practice; p < 0.005) and by 4% in Würzburg (from 9.9 to 9.5; p = 0.620), respectively. First-dose vaccinations for MMR (MMR or MMRV vaccine) did not change significantly in both regions.

Conclusion

Acceptance of V vaccination depends in part on the use of combination vaccine.     

The effectiveness of influenza vaccination in preventing hospitalizations in children in Hong Kong, 2009–2013

Background

Influenza vaccination is widely recommended every year to protect individuals against influenza virus infection and illness. There are few published estimates of influenza vaccine effectiveness against hospitalization in children or from subtropical regions.

Methods

We conducted a test-negative year-round study between October 2009 and September 2013, recruiting children 6 months to 17 years of age admitted to two hospitals in Hong Kong with a febrile acute respiratory infection. Cases were tested for influenza A and B and conditional logistic regression was used to estimate vaccine effectiveness comparing influenza vaccination history of the trivalent influenza vaccine (TIV) among patients testing positive versus negative for influenza, adjusting for age and sex and matching by calendar week of recruitment.

Results

Overall vaccine effectiveness against hospitalization with laboratory-confirmed influenza A and B was estimated to be 61.7% (95% CI: 43.0%, 74.2%). The estimated vaccine effectiveness against A(H3N2) was 36.6% (95% CI: −25.5%, 67.9%) compared to 71.5% (95% CI: 39.4%, 86.6%) for A(H1N1)pdm09 and 68.8% (95% CI: 41.6%, 83.3%) for B.

Conclusions

Vaccine effectiveness against hospitalization in children varied from year to year, but was moderate to high overall even in an area with influenza activity throughout the year.     

Evaluation of measles–rubella vaccination for mothers in early puerperal phase

BackgroundThe postpartum period is an ideal opportunity to vaccinate mothers with inadequate immunity to vaccine-preventable diseases including measles and rubella.MethodsA prospective study of measles–rubella (MR) vaccination in the early puerperal phase was conducted in 171 mothers, who had insufficient antibody titers when screened for immunity to measles (≤1:4 on the neutralization test [NT]) or rubella (≤1:16 on the hemagglutination inhibition [HI] test) during pregnancy. To evaluate the efficacy of MR vaccination in the postpartum period, we determined their post-vaccination antibody titers and immune responses to vaccination, and investigated the association between these and their prolactin (PRL) levels and Th1/Th2 ratios at the time of vaccination. We also examined the passage of viral RNA and antigen into breast milk.ResultsOf the 169 participants who completed the study schedule, 117 and 101 had low antibody titers against measles and rubella, respectively. In the measles-seronegative group, the antibody-positive rate was 87% on the NT assay, and the NT geometric mean antibody titer was 11.4 (95% confidence interval [CI], 10.0–13.0). In the rubella-seronegative group, the antibody-positive rate was 88% on the HI test assay, and the HI geometric mean antibody titer was 64.0 (95% CI, 53.9–76.0). There was no association between the post-vaccination antibody titers and the PRL levels or Th1/Th2 ratios at the time of vaccination. In the rubella-seronegative group, subjects with higher Th1/Th2 ratios showed higher rates of responsiveness than those with lower ratios (P = 0.045). Although measles virus RNA was isolated from the breast milk of two vaccinated mothers, breastfeeding was not associated with clinical disease in any infants.ConclusionMR vaccination in the early puerperal phase is considered an effective way to prevent the diseases, regardless of the mother's immunological status and hormonal milieu.     

Impact of five years of rotavirus vaccination in Finland – And the associated cost savings in secondary healthcare

IntroductionThis study aimed to estimate the impact of the national rotavirus (RV) vaccination programme, starting 2009, on the total hospital-treated acute gastroenteritis (AGE) and severe RV disease burden in Finland during the first five years of the programme. This study also evaluated the costs saved in secondary healthcare by the RV vaccination programme.MethodsThe RV related outcome definitions were based on ICD10 diagnostic codes recorded in the Care Register for Health Care. Incidences of hospitalised and hospital outpatient cases of AGE (A00-A09, R11) and RVGE (A08.0) were compared prior (1999–2005) and after (2010–2014) the start of the programme among children less than five years of age.ResultsThe reduction in disease burden in 2014, when all children under five years of age have been eligible for RV vaccination, was 92.9% (95%CI: 91.0%–94.5%) in hospitalised RVGE and 68.5% (66.6%–70.3%) in the total hospitalised AGE among children less than five years of age. For the corresponding hospital outpatient cases, there was a reduction of 91.4% (82.4%–96.6%) in the RVGE incidence, but an increase of 6.3% (2.7%–9.9%) in the AGE incidence. The RV vaccination programme prevented 2206 secondary healthcare AGE cases costing €4.5 million annually. As the RV immunisation costs were €2.3 million, the total net savings just in secondary healthcare costs were €2.2 million, i.e. €33 per vaccinated child.DiscussionThe RV vaccination programme clearly controlled the severe, hospital-treated forms of RVGE. The total disease burden is a more valuable end point than mere specifically diagnosed cases as laboratory confirmation practises usually change after vaccine introduction. The RV vaccination programme annually pays for itself at least two times over.     

Mumps disease in Beijing in the era of two-dose vaccination policy, 2005–2016

BackgroundSince the introduction of mumps-containing vaccines (MuCV) in 1995 in Beijing, two-dose MuCV vaccination policy has been used, with the 1st and 2nd doses given at 18 months and 6 years of age, respectively.MethodsMumps epidemiology during 2005–2016 was described using surveillance data. Vaccine effectiveness (VE) of MuCV against disease was estimated for cases born during 2002–2009 and reported in 2016. VE against complications was estimated for all cases. MuCV coverage was estimated for children born during 1999–2015 using data from Beijing Immunization Information System.ResultsOverall mumps incidence decreased from 30.38/100,000 persons in 2005 to 10.26/100,000 persons in 2016. Incidence declines in children aged <15 years. No significant incidence change occurred in adults aged ≥20 years. Incidence in persons aged 15–19 years increased by 132.73% in 2012 when compared with in 2005. Rates of meningitis/encephalitis, orchitis, and other complications among cases decreased during 2005–2016. The majority (97%) of outbreaks occurred in schools. Total number of outbreaks and average outbreak size decreased during 2005–2016. Among outbreak-related cases, 69.54%, 29.67% and 0.79% had received 0 dose, 1dose and 2 doses of MuCV, respectively. Coverage of the 1st MuCV dose at 2–5 years of age increased by 42.75% during 2005–2016. Coverage of the 2nd MuCV dose at 6–14 years of age increased by 12.87% during 2013–2016. Overall VE estimates of MuCV against mumps disease were 74.51% (95% CI: 65.57–81.34%) for 1 dose and 83.16% (95% CI: 78.60–86.31%) for 2 doses. Both VE estimates increased by birth cohorts. VE estimate against complications for 2-dose MuCV was higher than for 1 dose.ConclusionsIncreasing MuCV coverage achieved declining mumps incidence and complication rate. Current epidemiology supported 2-dose MuCV vaccination policy. The incidence rise in persons aged 15–19 years in 2012 and waning immunity for the 2nd MuCV dose merited close follow-up.     

Mandatory vaccination of infants in France: Is that the way forward?

In this opinion paper, the authors argue that the extension of mandatory immunization of infants up to two years of age from three diseases (diphtheria, tetanus, poliomyelitis) to 11 diseases, introduced in France in January 2018, is not a sustainable response to the challenge of controlling vaccine-preventable diseases. In France in 2017, infant immunization coverage (IC) rates were sufficiently high or increasing (hepatitis B), except for measles, mumps and rubella (MMR) and meningococcus C disease. Even if vaccination obligation makes it possible to achieve the MMR IC objectives among infants, communication programmes and supported advice from GPs are essential for the catch-up of susceptible adults to obtain herd immunity. The impact of mandatory immunization on hesitancy remains uncertain, and it contradicts the evolution of the patient’s role in the governance of his own health and the principle of autonomy. Numerous studies have shown that interventions and advice from health professionals improve vaccine acceptance. To correct the poor implementation of some vaccination programmes by health professionals, strong communication and resources from health authorities are needed, rather than a retreat towards obligation. Reducing missed opportunities and increasing access to immunization are essential objectives. Finally, an immunization policy based on primary care and a patient-centred approach to each vaccination are more likely to reduce vaccine hesitancy, sustainably.     

Modelling the epidemiological impact of rotavirus vaccination in Germany – A Bayesian approach

Background

Rotavirus (RV) infection is the primary cause of severe gastroenteritis in children aged <5 years in Germany and worldwide. In 2013 the German Standing Committee on Vaccination (STIKO) developed a national recommendation for routine RV-immunization of infants. To support informed decision-making we predicted the epidemiological impact of routine RV-vaccination in Germany using statistical modelling.

Methods

We developed a population-based model for the dynamic transmission of RV-infection in a vaccination setting. Using data from the communicable disease reporting system and survey records on the vaccination coverage from the eastern federal states, where the vaccine was widely used before recommended at national level, we first estimated RV vaccine effectiveness (VE) within a Bayesian framework utilizing adaptive Markov Chain Monte Carlo inference. The calibrated model was then used to compute the predictive distribution of RV-incidence after achieving high vaccination coverage with the introduction of routine vaccination.

Results

Our model estimated that RV-vaccination provides high protection against symptomatic RV-infection (VE = 96%; 95% credibility interval (CI): 91–99%) that remains at its maximum level for three years (95% CI: 1.43–5.80 years) and is fully waned after twelve years. At population level, routine vaccination at 90% coverage is predicted to reduce symptomatic RV-incidence among children aged <5 years by 84% (95% prediction interval (PI): 71–90%) including a 2.5% decrease due to herd protection. Ten years after vaccine introduction an increase in RV incidences of 12% (95% PI: −16 to 85%) among persons aged 5–59 years and 14% (95% PI: −6 to 109%) within the age-group >60 years was predicted.

Conclusion

Routine infant RV-vaccination is predicted to considerably reduce RV-incidence in Germany among children <5 years. Our work generated estimates of RV VE in the field and predicted the population-level impact, while adequately addressing the role of model and prediction uncertainty when making statements about the future.     

Knowledge,attitudes and practices related to influenza illness and vaccination in children: Role of awareness campaigns in changing parents’ attitudes toward influenza vaccination in Jordan

BackgroundInfluenza infection is associated with a significant health burden in children, especially in developing countries. The influenza vaccine is an important preventive strategy for flu illness. Aim of this study to assess knowledge, attitudes and practices (KAP) related to influenza illness and vaccination in children in the Jordanian population and to study the effect of awareness campaigns on changing the attitudes of parents toward vaccinating their children against influenza.MethodsA cross-sectional study was conducted among families visiting shopping malls and parks in November 2016. A questionnaire was administered via in-person interviews. Answers to KAP questions regarding influenza illness and vaccination were summed, with a total KAP score of 30. Facts about influenza illness and vaccination were explained to parents and provided in printed pamphlets.ResultsThere were 1241 respondents. 10.9% of participants had vaccinated their children during the last season 2015/2016. The mean KAP score (standard deviation) was 16.21 (4.61). People living in urban areas, with high monthly income >600 JD and healthcare workers had higher KAP scores than their counterparts. Compared to other sources of information about the influenza vaccine, health resources correlated most with vaccinating children. Awareness and educational pamphlets changed attitudes positively in 29% of parents who refused the influenza vaccine for their children.ConclusionsAwareness about influenza illness and vaccination is insufficient, and the coverage rate of influenza vaccination in children is low in the Jordanian population. Implementing public health policies is necessary to spread knowledge about influenza illness and vaccination and to promote the practice of receiving the influenza vaccine in children. Educational campaigns are helpful in changing the attitudes of parents toward vaccinating their children against the flu.     

Herpes zoster in the context of varicella vaccination – An equation with several variables

BackgroundVaricella and herpes zoster (HZ), diseases both caused by the varicella zoster virus (VZV), are vaccine-preventable. However, the hypothesis that childhood varicella vaccination may increase the incidence of HZ hinders varicella universal routine vaccination (URV) implementation in many countries.MethodsThis non-systematic and narrative review of the literature considers the burden of varicella and HZ, and the effectiveness of the respective vaccines. We present the factors involved in the interplay between varicella vaccination and HZ incidence, including the roles of exogenous and endogenous boosting. We review HZ incidence model predictions, and compare these with real-world evidence, which has accumulated since varicella URV was introduced.ConclusionAlthough more research and longer surveillance are needed, available real-world evidence has not confirmed the model-predicted increase in HZ incidence, associated with childhood varicella URV. Although there is a rising incidence of HZ globally, this trend appears to be predominantly the result of an aging population. Vaccination against varicella in childhood provides significant benefits with respect to the medical, societal and economic burdens of the disease. Therefore, a theoretical concern of an increased burden of HZ with varicella vaccination programs should not prevent children from being protected against the disease.     

Do changes in policy affect vaccine coverage levels? Results of a national study to evaluate childhood vaccination coverage and reasons for missed vaccination in Italy

To evaluate the impact of actions taken in Italy since 1998 to improve vaccination coverage, a national EPI-survey was performed in 2003. Overall, 4602 children aged 12-24 months participated in the study; coverage was calculated for three doses of DT, polio, HBV, pertussis, and Hib, and for one dose of MMR/measles vaccine for children > or =16 months of age. Since 1998, when the last national survey was conducted, DT, polio, and HBV coverage have remained consistently high (95%), while pertussis, Hib, and MMR/measles significantly increased. Pertussis coverage reached the 95% target, and Hib is close to target (87%). Improving MMR coverage (77%), however, remains a national priority.