Abstract
Due to median vaccination coverage far from elimination level, Italy is still an European country with high number of measles cases per million of people. In this study we explored potential socioeconomic, medical and demographic factors which could influence the propensity of family members for measles vaccination schedule.
A cross-sectional study was performed through a questionnaire administered to the parents of children who received the first dose of MMR vaccine in two different vaccination centers in the Palermo area from November 2012 to May 2013.
Overall, the role played by internet (OR 19.8 P = 0.001) and the large number of children in a family (OR 7.3 P ≤ 0.001) were the factors more associated to be unvaccinated, whereas the birth order of the child (OR 0.3 P = < 0.05 for the oldest children vs. the closer young one) and reporting a lack of MMR vaccination as a “personal decision” (OR 0.19 P ≤ 0.01) inversely correlated with the risk of quitting vaccination.
These findings can be useful for a better knowledge of disaffection to vaccination practice in local settings and could contribute to improve and maintain timely uptake, suggesting approaches to optimize the uptake of MMR tailored to the needs of local populations.
Introduction
The dramatic reduction of the incidence of vaccine-preventable diseases during the last decades, contributed to the public perception that the severity of the disease and susceptibility to it have decreased.Citation1 Recent parental concerns about perceived vaccine safety issues, such as a purposed association between vaccines and autism, although not supported by a credible body of scientific evidence, have led increasing numbers of parents to refuse or delay vaccination for their children.Citation2-Citation4
The introduction of measles vaccination in Europe in the 1960s and 1970s significantly changed the epidemiology of measles. While some European countries virtually eliminated measles within a few years after introducing measles vaccination, other countries who failed to achieve the high vaccination coverage required for elimination noticed only limited impact on incidence, experiencing how rapidly evolving outbreaks over 6–8 mo in the pre-vaccine era have been replaced by comparatively slowly propagating outbreaks over longer periods, several years sometimes.Citation5
In Italy, measles vaccination was first introduced in 1976 and, to date, is included in the national immunization program in association with Mump and Rubella as MMR associated vaccine. MMR vaccine is provided free of charge between the 13th and 15th mo of age, as first dose, and between 5th and 6th y, as second dose, by local vaccination centers, because it was included in the list of “essential health interventions”.Citation6 However, the uptake of measles vaccine still remain relatively low in Italy with irregular levels across regions.
In Sicily also, due to non-satisfactory vaccine coverage, in 2010 and 2011 a prolonged outbreak accounting for more than 2000 cases affecting essentially peoples of two age classes: 1–4 and 15–20 y old was registered.Citation7 In those years, vaccination coverage for the first dose of MMR was 85.3% and 86.8%, respectively.Citation8
The aim of the study is to evaluate the refuse level of first MMR dose, a better knowledge of the social-demographic characteristics associated with refused vaccination, and the reasons reported by parents for their child’s immunization status.
Materials and Methods
A cross-sectional study was performed in two vaccination centers of Palermo area from November 2012 to May 2013. The user base population of the centers analyzed is about 1180 children per birth cohort, thus representing about 24% of the target population per year. The population of study included parents who accepted/refused the first dose of MMR vaccination for children among the thirteenth and the twentieth month of birth. A total of 489 parents in the two centers satisfied the study criteria although 46 were not included because they refused to undergo interview. Overall, 443 parents were interviewed. Of these, 356 (80.4%) were mothers with a mean age of 32.8 y (95% CI: 32.3–33.3) and 87 (19.6%) were fathers with a mean age of 36.2 y (95% CI: 35.6–36.8). All enrolled individuals were given a telephonic questionnaire, by two standardized physician interviewer, that investigated demographic and socio-economic factors of parents and medical characteristics of parent’s children. At least five attempts to contact families of selected children were made, before excluding them. Informed consent was obtained according to Italian law, and confidentiality of responses was assured. The questionnaire was pre-tested on a convenience sample of parents to ensure clarity of interpretation and ease of completion to improve validity of responses.
Measures
Measures were reported by the main respondent (mother and father) during interviews. The outcome measure was represented by MMR vaccine status at age 13–15 mo and was obtained from the database of the vaccination centers. Children’s parents were classified as unimmunized (received no combined MMR) and partially vaccinated (received one combined MMR). Our criteria for refusing vaccination allowed for a 5-mo grace period for receipt of MMR, and a parent who has decided to vaccinate his/her children within 5 mo of becoming age-eligible was considered to be vaccinated.
The covariates were indicators of doubt about vaccines. We explored parent’s socio-demographic and economic characteristics (age, country of origin, educational level, economic referred level and unemployed status in the last 2 y) as well as their knowledge about MMR vaccination (rules for administration of MMR vaccine, reason to vaccinate/not vaccinate for MMR, informative sources about MMR and role of websites and pediatrician towards MMR). Furthermore, children’s demographic and medical factors were also investigated (sex, age, birth order, previous hospital admission, chronic disease, adverse reaction to former vaccination, chronic drugs use).
Parents’ educational level was classified according to the Italian law: primary school (5 y of education), secondary school (3 y of education), high school (5 y of education) and degree (5 y of education). Parents’ economic level reported was scored on a 10-point Likert scale with options ranging from “1” (low level) to “10” (high level). In Sicily, like other Italian regions, the MMR vaccine is highly recommended by the Ministry of Health and administrated free of charge between the thirteenth and fifteenth month of life.Citation6 Hence, the degree of knowledge of parents about the rules for administration of MMR vaccine were also evaluated. Furthermore, were also investigated reasons for scarce adherence to first dose of MMR classifying according to Millemnium Cohort Study as “practical” (such as missing an appointment), “medical” (eg, child had chronic illness), “conscious decision” (including fear and links with autism) or “other” (which included “I don’t know”).Citation9 Sample size was calculated with the use of software Epi Info to find the factors associated with parent’s decision not to vaccinate their children for MMR. All the other socio-demographic, economic and medical variables, except the continuous ones, were in “yes/no” format.
Statistical analysis
The level of significance chosen for all analyzes was 0.05 two-tailed. For categorical variables absolute and relative frequencies were calculated, while continuous variables not normally distributed were represented as median (interquartile range, IQR). The normal distribution was assessed with the Shapiro–Wilk test. Differences in socio-demographic, economic and medical characteristic were tested using Student t test for continuous variables normally distributed, Wilcoxon-Mann-Whitney test on the equality medians for continuous variables non normally distributed and XCitation2 tests for categorical variables. The odds ratio (OR) and 95% confidence interval (CI95%) were also calculated.
Furthermore a bivariable logistic regression analysis was performed to examine the association of MMR refusal and socio-demographic, economic and medical characteristics. All variables that were found to be statistically significant on bivariable analysis were included in a multivariable logistic regression model. The goodness of fit was calculated for each model and the model with the lowest log-likelihood ratio test was considered to have the best predictive ability. The adjusted OR (adj-OR) with CI95% was also calculated for variables that are not distributed in the final model. Data analysis was performed with the software Stata/MP 11.2.
Results
In are depicted the socio-demographic characteristics of the 443 parents finally enrolled into the study. Overall, 66 (14.9%) refused the first dose of MMR and 377 (85.1%) decided to take the first dose of MMR for their children.
Table 1. Socio-demographic, economic and medical factors of parents and their children
The mothers of unvaccinated were more frequently Italian (95.5% vs. 89.9% P < 0.001) and had more children (2 vs. 1 P < 0.001) than mothers of vaccinated children. Parents of unvaccinated children have taken their decision to refuse MMR vaccine often with the second born (50.0% vs. 39.5%) rather than with the first one (25.8% vs. 49.8%) compared with the choices of vaccinated children’s parents (P = 0.002).
About medical characteristics, the parents of unvaccinated compared with those of vaccinated children had: increased consumption of drugs for children’s chronic diseases (18.2% vs. 8.3% P = 0.016) and higher prevalence of children’s chronic diseases (25.8% vs. 10.6% P = 0.001).
The parents of unvaccinated children less frequently thought that the vaccination was mandatory (39.4% vs. 63.7% P < 0.001), they used most frequently as sources of information on MMR vaccination websites (24.2% vs. 9.3% P < 0.001) and other mass media (24.2% vs. 10.1 P = 0.01) and less commonly family/friends (13.6 vs. 27.1% P = 0.02) compared with parents of vaccinated children. Furthermore, the parents of unvaccinated children more frequently reported that the websites (31.8% vs. 5.3% P < 0.001) and the pediatricians (6.0% vs. 1.3% P = 0.044) had a negative role on their decision.
Unvaccinated parents compared with those vaccinated reported most commonly medical reasons as reason for refusing MMR vaccine (50.0% vs. 28.4% P < 0.001) but less practical (42.4% vs. 53.3% P < 0.001) and conscious decision (4.6% vs. 23.8% P < 0.001), hence as motivation to be vaccinated reported less frequently medical reasons (42.5% vs. 61.8% P < 0.001).
shows the results of the multivariable analysis of the relationship between the parents who refused MMR and the variables that were significant in bivariable analysis. A significant direct relationship was found between the rejection of MMR and the negative role played by websites on the decision to vaccinate their children (Adjusted OR 19.78, P = 0.001) and the same was “having a greater number of children” (Adjusted OR 7.31 P < 0.001). A significant inverse relationship was found between parents who refused MMR and birth order of their children (Adjusted OR 0.35, P = 0.038) and conscious decision as reason for not to get vaccinated (Adjusted OR 0.19, P = 0.01).
Table 2. Multivariable logistic regression of factors directly and inversely associated with parents who refused MMR
Discussions
The Italian Plan for Elimination of Measles and Congenital Rubella (PNEMoRC 2010–2015) has sets the adoption of ordinary and extraordinary actions for the achievement, by 2015, of a vaccination coverage >95% for the first dose of MMR within 24 mo of life.Citation10 Several factors have been identified as determinants of potential deficient immunization rates in infancy and childhood. The effect of some factors could depends on country-specific circumstances; for example, on parent’s attitudes and beliefs regarding vaccination. This study has investigated the phenomenon of refusal of MMR vaccination in a sample population of the greatest city in Sicily and which reasons lead parents to not vaccinate for first dose MMR.
About 15 percent of the sample analyzed decided not to vaccinate their child for first shot of MMR. This data highlights a sub-optimal vaccine uptake in Sicily respect to national and international vaccination coverage.Citation8,Citation11 This vaccination coverage can lead, in the future, to experience slowly propagating outbreaks with longer intervals and consequently with an effect on the age distribution of cases during outbreaks.Citation5 These information must be known and periodically reviewed in order to achieve adequate vaccination coverage in hard to reach groups.
In particular this study suggests that the factor more affecting the refusal of MMR was the negative role played by websites on parents’ decision to vaccinate their children. To date about 80% of users access the network to inquire about health issues, of these one-fifth seek data on vaccines, and 70% admit to be conditioned.Citation12 It was observed that a single access to an anti-vaccination site for just 5–10 min, increase the perception of the risks associated with the use of vaccines and decrease the perception of risks from non-use of vaccines.Citation13 Moreover it was found that the adverse publicity has a gradual build-up and prolonged effect, rather than an instant impact on the decision to vaccinate for MMR.Citation14
Additionally, to have a mother with a greater number of children was shown to be an important negative predictor for MMR in toddlers in the current study. Number of siblings was also previously founded to predict a child’s immunization status in a study conducted on either mandatory or state-funded routine vaccines.Citation15 The importance of ensuring that infants from larger families complete their primary immunizations on time should be made clear in immunization publicity because these unvaccinated children of larger families are at increased risk of exposure to infection from younger siblings.
A condition founded to be associated with the probability of rejecting MMR was a lower birth order of the children. This result contrasts with those of previous studies.Citation16 These can be explained because parents acquire adequate knowledge on vaccination with younger children after experienced a wrong treatment of measles that was learned from the pre-vaccine era.Citation17
Finally conscious decision was another factor that reduce the probability to refuse MMR. In the case of MMR a full information can lead to a reduction of missed vaccination in particular in hard to reach parents. This fact was also confirmed in a study where parents who refused combined vaccines acting on the uncertainty and the lack of clear information.Citation18,Citation19
The main limitation of the study appears to be the only setting of Palermo area and small number of cases. However, this study can provide an initial data that have to be extend to the national setting through the conduction of a multicenter survey.
Nonetheless, this paper provides important information on the barriers experienced by families during times of no outbreak to improve and sustain the current MMR program. Furthermore in this study, the distinction between compulsory and optional vaccinations (a distinguishing aspect of childhood immunization policy in Italy) was also taken into account. Indeed the immunization status of children was extracted from the medical records of involved vaccination centers. These determine better reproducibility of the study compared with others.Citation20
Identifying populations at risk of underimmunization is essential to planning effective interventions for increasing vaccine coverage. Among the tools realized in Italy to counteract misinformation on vaccine there is the project “VaccinarSI”, promoted by the Italian Society of Hygiene. The project has the aim to reply the lack of information on the web and at the same time, to show the validity of the vaccinations. The portal also provides scientific data developed in a clear and simple way, and accompanied by verifiable sources.Citation21 It would also be necessary to conduct a Health Technology Assessment on the abolition of mandatory vaccination in Italy.
| Abbreviations: | ||
| CI95% | = | 95% confidence interval |
| IQR | = | interquartile range |
| MMR | = | Measles, Mumps and Rubella |
| OR | = | odds ratio |
| mo | = | months |
| y | = | years |
Disclosure of Potential Conflicts of Interest
No potential conflicts of interest were disclosed.
Acknowledgements
The Authors thank Dr Nicola Casuccio (Department of Medical Prevention, U.O.C. of Public Health, Epidemiology and Preventive Medicine), Dr Claudio D’Angelo (Department of Medical Prevention, U.O.S. Prevention of Infectious Diseases), Dr Antonino Zambito (Department of Medical Prevention, Responsible for Pallavicino Vaccination Center), and Dr Mirella Patané (Department of Medical Prevention, Responsible for Oreto Vaccination Center), for their support in designing and conducting the study.
Related Research Data
References
- ChenRT, HibbsB. Vaccine safety: current and future challenges. Pediatr Ann1998; 27:445 - 55; http://dx.doi.org/10.3928/0090-4481-19980701-11; PMID: 9677616
- DeStefanoF. Vaccines and autism: evidence does not support a causal association. Clin Pharmacol Ther2007; 82:756 - 9; http://dx.doi.org/10.1038/sj.clpt.6100407; PMID: 17928818
- SchechterR, GretherJK. Continuing increases in autism reported to California’s developmental services system: mercury in retrograde. Arch Gen Psychiatry2008; 65:19 - 24; http://dx.doi.org/10.1001/archgenpsychiatry.2007.1; PMID: 18180424
- SmithMJ, EllenbergSS, BellLM, RubinDM. Media coverage of the measles-mumps-rubella vaccine and autism controversy and its relationship to MMR immunization rates in the United States. Pediatrics2008; 121:e836 - 43; http://dx.doi.org/10.1542/peds.2007-1760; PMID: 18381512
- European Center for Disease Control and Prevention (ECDC). European monthly measles monitoring (EMMO) February 21, 2012 Accessed May 2, 2014 at: http://www.ecdc.europa.eu/en/publications/_layouts/forms/Publication_DispForm.aspx?List=4f55ad51-4aed-4d32-b96
- Italian Ministry of Health. National Vaccination Prevention Plan 2012-2014. [Piano nazionale prevenzione vaccinale 2012-2014.] Italian Official Bulletin 12 Mar 2012;no. 60. [Gazzetta Ufficiale Repubblica Italiana 12 Mar 2012;no. 60]. Accessed May 2, 2014.
- Istituto Superiore di Sanità. Computerized System of Infectious Diseases. [Sistema Informatizzato Malattie Infettive.] Accessed May 2, 2014. Available at https://www.iss.it/site/rmi/simiweb/
- Italian Ministry of Health. Childhood Vaccination Coverage. 2008. accessed May 22, 2014 at http://www.salute.gov.it/portale/temi/p2_6.jsp?lingua=italiano&id=811&area=Malattie%20infettive&menu=vaccinazioni
- Plewis I, Ketende S. Millennium Cohort Study: technical report on response. 1st edn. London Centre for Longitudinal Studies, 2006.
- Italian Ministry of Health. Plan for the Elimination of Measles and Congenital Rubella 2010-2015 (PNEMoRc). [Piano Nazionale per l’eliminazione del morbillo e della rosolia congenita].Accessed May 2, 2014 at http://www.salute.gov.it/imgs/C_17_pubblicazioni_1519_allegato.pdf
- Centers for Disease Control and Prevention (CDC). National, state, and local area vaccination coverage among children aged 19-35 months - United States, 2012. MMWR Morb Mortal Wkly Rep2013; 62:733 - 40; PMID: 24025754
- KataA. Anti-vaccine activists, Web 2.0, and the postmodern paradigm--an overview of tactics and tropes used online by the anti-vaccination movement. Vaccine2012; 30:3778 - 89; http://dx.doi.org/10.1016/j.vaccine.2011.11.112; PMID: 22172504
- BetschC, RenkewitzF, BetschT, UlshöferC. The influence of vaccine-critical websites on perceiving vaccination risks. J Health Psychol2010; 15:446 - 55; http://dx.doi.org/10.1177/1359105309353647; PMID: 20348365
- FriederichsV, CameronJC, RobertsonC. Impact of adverse publicity on MMR vaccine uptake: a population based analysis of vaccine uptake records for one million children, born 1987-2004. Arch Dis Child2006; 91:465 - 8; http://dx.doi.org/10.1136/adc.2005.085944; PMID: 16638784
- LiJ, TaylorB. Factors affecting uptake of measles, mumps, and rubella immunisation. BMJ1993; 307:168 - 71; http://dx.doi.org/10.1136/bmj.307.6897.168; PMID: 8343745
- Gavrielov-YusimN, BattatE, NeumannL, FrigerM, BalicerRD. Birth order and private voluntary immunization--a study of 110,902 children. Vaccine2012; 30:442 - 7; http://dx.doi.org/10.1016/j.vaccine.2011.10.060; PMID: 22079267
- MayT. Public communication, risk perception, and the viability of preventive vaccination against communicable diseases. Bioethics2005; 19:407 - 21; http://dx.doi.org/10.1111/j.1467-8519.2005.00452.x; PMID: 16222856
- HiltonS, PetticrewM, HuntK. ‘Combined vaccines are like a sudden onslaught to the body’s immune system’: parental concerns about vaccine ‘overload’ and ‘immune-vulnerability’. Vaccine2006; 24:4321 - 7; http://dx.doi.org/10.1016/j.vaccine.2006.03.003; PMID: 16581162
- BrownKF, LongSJ, RamsayM, HudsonMJ, GreenJ, VincentCA, KrollJS, FraserG, SevdalisN. U.K. parents’ decision-making about measles-mumps-rubella (MMR) vaccine 10 years after the MMR-autism controversy: a qualitative analysis. Vaccine2012; 30:1855 - 64; http://dx.doi.org/10.1016/j.vaccine.2011.12.127; PMID: 22230590
- PearceA, MindlinM, Cortina-BorjaM, BedfordH. Characteristics of 5-year-olds who catch-up with MMR: findings from the UK Millennium Cohort Study. BMJ Open2013; 3:e003152; http://dx.doi.org/10.1136/bmjopen-2013-003152; PMID: 23864213
- Italian Society of Hygiene (SItI). VaccinarSi Accessed May 2, 2014; http://www.vaccinarsi.org/