Elsevier

Public Health

Volume 135, June 2016, Pages 66-74
Public Health

Original Research
Surveillance for adverse events following immunization (AEFI) for 7 years using a computerised vaccination system

https://doi.org/10.1016/j.puhe.2015.11.010Get rights and content

Highlights

  • The immunization registry, SIV, demonstrates advantages for passive surveillance.

  • After more than 13 million vaccines doses administered, the AEFI reporting rate was 12.4/100,000 doses.

  • Differences in reporting rate by sex, age and vaccine were identified.

  • SIV allows detecting shifts in reporting rate on real time for specific vaccines.

Abstract

Objectives

The surveillance of vaccine safety is an essential requirement in vaccination programmes. Computerized immunization registries such as the Vaccination Information System (SIV) of Valencian Community (Spain) offer the opportunity to estimate the incidence of adverse events according to individual information. The aim of the study was to analyze adverse events following immunization reported through SIV from 2005 to 2011 by age, sex, type of vaccine and dose, and adverse event, and highlight the advantages of this type of reporting.

Study design

A retrospective cohort study of subjects vaccinated in the Valencian Community using population health databases was carried out.

Methods

Analysis of vaccinations and reported AEFI via SIV in Valencian Community was carried out.

Results

More than 13 million vaccines doses were administered during 2005 through 2011, the reporting rate of adverse events was 12.4/100,000 doses administered with the highest value in 2009 (27.4), with differences by age and sex. DTaP vaccine had the highest reporting in children (96.6/100,000) while influenza A(H1N1)pdm09 in adults (87.7/100,000). An increased reporting of adverse events was seen with DTaP in children 5–6 years of age, detected in real time, drove to swap this vaccine to a low dose Tdap which was followed by a decrease in administration site events.

Conclusions

SIV demonstrates advantages for passive surveillance. Reporting rates by individual characteristics are calculated accurately and it also allows detecting shifts in reporting rate on real time for specific vaccines. The study shows that vaccines included in the routine vaccination schedule for children and adult vaccination programs are safe.

Introduction

Recommendations for vaccination represent a dynamic balance between benefits and risks.1 Before immunization, vaccine-preventable diseases were highly prevalent and the benefit for vaccination was easy to estimate and perceive. As the incidence of disease decreased, concerns about vaccine safety increased. This scenario highlights the importance of obtaining data about actual events occurring after vaccine administration in a high number of people in order to maintain the risk-benefit ratio and the reliability on vaccination programmes.2, 3

Electronic vaccine registries are important tools to monitor national immunization programmes.4 The availability of unique personal identifiers such as that provided by the Population Information System (SIP) of the Valencian Community,5 represents an opportunity to link vaccine registers to disease data and to identify specific health outcomes, and also to investigate vaccine safety signals of existing and new vaccine programmes.6

The objectives of passive surveillance systems of Adverse Events Following Immunization (AEFI) include: to detect new, unusual or rare vaccine adverse events; to assess the safety of newly licensed vaccines and to determine patient risk factors for particular types of adverse events.7, 8 The advantage of Vaccination Information System (SIV) is that it provides individual information of the vaccinated person, so data related with age, sex and risk group is complete and reliable.

The Valencian Community has a population of five million inhabitants, representing slightly over 10% of the Spanish population. The immunization registry of the Valencian Community was set up in 2002 and since then, over 30 million vaccinations have been registered. The registry of vaccine adverse events through the SIV began in 2005.5

The main objective of the study was to calculate the reporting rates of reported AEFI through SIV of the Valencian Community between January 2005 and December 2011 by age, sex, type of vaccine and dose, and to highlight the advantages of computerized immunization registers.

Section snippets

Description of SIV

Immunizations carried out in the Valencian Community are recorded through SIV. Over 1800 health care workers have access to this immunization registration platform. SIV is a population-based individual register, linked to other health databases through a unique personal identification number (SIP). SIV includes patient data such as date of birth, sex and residence.

This system allows the individual registration of administered vaccines: type of vaccine, manufacturer, expiry date and batch number

Global data. Age and sex distribution of AEFIs

During the study period 13,174,685 vaccine doses were administered and 1637 AEFIs reported (rate 12.4/100,000 doses; 95%CI: 11.8–13.04) (Table 1). This represents 21.7% of the reports of adverse events after immunization reported in Spain. AEFIs reported to the PhV Center, through SIV increased from 85% in 2005 to 98% in 2011. AEFI reporting rate varied by year (Fig. 1): in 2005 rate 3.25/100,000 (95%CI: 2.53–4.18) and in 2009 rate 27.4 (95%CI: 25.3–29.7).

During the 7-year surveillance period,

Discussion

Post-licensure surveillance of AEFI is an integral part of immunization programmes. These passive surveillance systems have limitations such as underreporting or insufficient information on cases reported. Ambiguous denominators (i.e. number of vaccine doses administered in a given population) are also highlighted as a limitation for the calculation of the incidence of AEFIs.10, 11 However these systems provide useful information as trends and signals that can be detected even if incomplete

Ethical approval

Ethical approval was not required.

Funding

No funding has been received.

Conflict of interests

No conflict of interests to declare.

References (33)

  • P.R. Pittman

    Aluminum-containing vaccine associated adverse events: role of route of administration and gender

    Vaccine

    (2002)
  • K.L. Flanagan et al.

    Sex differences in the vaccine-specific and non-targeted effects of vaccines

    Vaccine

    (2011)
  • P.E. Fine et al.

    Individual versus public priorities in the determination of optimal vaccination policies

    Am J Epidemiol

    (1986)
  • C.M. Healy et al.

    How to communicate with vaccine-hesitant parents

    Pediatrics

    (2011)
  • R. Pebody

    Vaccine registers – experiences from Europe and elsewhere

    Euro Surveill

    (2012)
  • E. Pastor Villalba et al.

    Sistema de Información Vacunal [Vaccination Information System]. Valencia: generalitat. Conselleria de Sanitat

    (2009)
  • Cited by (19)

    • Vaccine adverse event reporting system (VAERS): Evaluation of 31 years of reports and pandemics’ impact

      2022, Saudi Pharmaceutical Journal
      Citation Excerpt :

      However, despite the high incident rate of bell’s palsy and narcolepsy which reported by Li et al, this study results show low rates of these AESIs (Li et al., 2021b). Results of our study show that most of AEFIs are nonserious and more than 80 % of them appear within first few days following vaccination, which is consistent with results found in other articles (Alguacil-Ramos et al., 2016; Fadare et al., 2019; Mentzer et al., 2018). In addition, male and age group ≤ 5 years were more prone to serious AEFIs in consistent with findings from prior research (Fadare et al., 2019; Harris et al., 2017).

    • An exploratory analysis of the response to ChAdOx1 nCoV-19 (AZD1222) vaccine in males and females

      2022, eBioMedicine
      Citation Excerpt :

      The observation of greater reactogenicity in females following COVID-19 vaccination in our study is also seen for other COVID-19 vaccines. Both phase 2/3 clinical trial reports and real-world evidence gathered for BNT162b2, mRNA-1273 and Ad26.COV2-S9,26-28 describe greater reactogenicity in females than males, a pattern also observed with vaccines against other diseases including yellow fever, measles, mumps and rubella and influenza.29,3031 Fatigue and headache are also the two systemic reactions reported more commonly in females than males, in response to H1N1 vaccination30,32 and both local and systemic reactions are reported more commonly in females after both intramuscular and intradermal inactivated trivalent influenza vaccination.28

    • Rapid assessment of enhanced safety surveillance for influenza vaccine

      2019, Public Health
      Citation Excerpt :

      SIV is integrated into the health systems of the region, so nominal immunization data could be linked to the information contained in other health record databases (medical history, hospital discharge records, pharmacovigilance, epidemiological, and microbiological surveillance system). SIV of the Valencia region has previously proven its potential in the immunization safety monitoring.3 A descriptive study of AEFI reports of vaccinated population against influenza in the Valencia region has been performed.

    • Effect of sex on vaccination outcomes: important but frequently overlooked

      2018, Current Opinion in Pharmacology
      Citation Excerpt :

      Despite this, the overriding experience is that females experience more AEFIs than males [1••] (Table 1). A recent Spanish analysis of >13 million vaccination episodes found a significantly higher AEFI rate to multiple vaccines among females (59.6%) compared to males [13•]. A Canadian study of almost 2500 AEFIs found 66.2% of events occurred in females with a female:male reporting ratio of 1.9 [14].

    View all citing articles on Scopus
    View full text