Search Results (66)

Background/Objectives: The aim of this study was to systematically assess Adverse Events Following Immunization (AEFI) among children following administration of the human papillomavirus (HPV) vaccine (Cervarix^®) included in the Dutch National Immunization Program (NIP) and to characterize the pattern and recurrence risk of AEFI after HPV revaccination. Methods: A longitudinal cohort event monitoring study, using patient-reported outcomes was used among recipients of the HPV vaccine at 10 years of age. Data were available for 3063 children following the first HPV vaccination and for 2209 children following the second HPV vaccination. Results: The most commonly reported AEFI following HPV vaccination were injection site reactions—reported by 46.5% of participants after the first dose and 31.9% after the second dose—followed by headache (8.2% and 3.9%, respectively) and joint pain (4.5% and 3.7%, respectively). Participants who received both HPV vaccine doses reported more AEFI after the first dose than after the second. Among girls, 61.2% reported at least one AEFI following the first dose, compared to 44.2% after the second dose. For boys, these percentages were 55.3% and 38.5%, respectively. This difference was statistically significant (p = 0.002). For some AEFI, such as injection site reactions, there appears to be a potential increased risk of recurrence following the second dose. Conclusions: This prospective longitudinal cohort event monitoring study showed that AEFI were more frequent after the first HPV dose and more frequent for girls compared to boys. An increased risk of recurrence was seen for AEFI, such as injection site reactions and headache. Furthermore, this study provides insight into the course of AEFI and the extent to which children were affected by these symptoms based on real-world data. Full article

Background/Objectives: Older adults face increased vulnerability to infectious diseases such as influenza, pneumococcal infections, and COVID-19. Vaccination remains a key public health strategy, yet coverage and adverse event data in this group are limited. This study aimed to assess the prevalence of vaccination and the occurrence of post-vaccination adverse events among individuals aged 55 and older in Płock, Poland, with particular attention to gender and age differences. Methods: A population-based cross-sectional study was conducted between January and November 2022 among 2040 adults aged ≥ 55 years. Participants completed a structured questionnaire on vaccination history (past 3 years) and adverse events following immunization (AEFI). Cognitive eligibility was assessed using the MMSE (≥27). Statistical analyses included t-tests, chi-square tests, and Pearson correlation coefficients with a significance level of p < 0.05. Results: COVID-19 vaccination was reported by 86.9% of participants, influenza vaccination by 45.5%, and pneumococcal vaccination by 15.1%. Women reported significantly more adverse events following COVID-19 vaccination compared to men (16.1% vs. 8.8%, p < 0.001). A weak negative correlation was observed between age and number of vaccinations received (r = −0.088, p = 0.001), while age was positively correlated with adverse events following COVID-19 vaccination (r = 0.175, p < 0.001). Influenza vaccination was more common among men than women (50.7% vs. 43.4%, p < 0.05). Conclusions: Vaccination coverage among older adults in Płock was highest for COVID-19 but remained suboptimal for influenza and pneumococcal vaccines. Women reported adverse events more frequently than men. These findings highlight the need for targeted vaccination strategies and gender-sensitive communication approaches. Full article

Vaccine marketing authorization holders (MAHs) are responsible for the conduction of global vaccine pharmacovigilance on their vaccine products. A safety signal is detected when a new adverse event (AE) or aspect of an AE occurs after exposure to the vaccine and warrants further investigation to determine whether a causal association may exist. Signal detection and evaluation (signal management) begins at the start of vaccine development, before an MAH submits an application for authorization to regulatory authorities, continues through the course of all clinical trials, and carries on beyond development into the post-marketing phase. As long as the vaccine remains authorized anywhere in the world, pharmacovigilance continues. During the time that the COVID-19 vaccine became widely available after authorization and approval, clinical trials were also ongoing, and therefore all clinical development and post-authorization safety information was closely monitored for safety by the MAH. MAH pharmacovigilance activities were adapted to manage the unprecedented volume of safety information that became available within a very short timeframe following worldwide vaccination campaigns. No vaccine had previously been administered to such a large number of individuals in such a short time, nor had there previously been a public health vaccine experience that was the subject of so many medical and non-medical writings. The MAH’s COVID-19 vaccine signal detection methods included the continuous review of accruing clinical trial data and the quantitative and qualitative analyses of spontaneously reported experiences. Review of published and unpublished medical literature and epidemiology-based analyses such as observed vs. expected analysis based on reported adverse events following immunization (AEFIs) played key roles in pharmacovigilance and signal management. All methods of signal detection and evaluation have caveats, but when considered in totality, can advance our understanding of a vaccine’s safety profile and therefore the risk–benefit considerations for vaccinating both individuals and large populations of people. All COVID-19 vaccines authorized for use were subject to an unprecedented level of pharmacovigilance by their individual MAHs, national regulatory authorities, public health organizations, and others during the years immediately following regulatory authorization and full approval. The intense worldwide focus on pharmacovigilance and the need for MAHs and regulatory/health authorities to quickly evaluate incoming safety information, spurred frequent and timely communications between national and regional health authorities and between MAHs and regulatory/health authorities, spotlighting a unique opportunity for individuals committed to patient safety to share important accruing safety information in a collegial and less traditionally formal manner than usual. The global pandemic precipitated by the SARS-CoV-2 virus created a significant impetus for MAHs to develop innovative vaccines to change the course of the COVID-19 pandemic. Pharmacovigilance also had to meet unprecedented needs. In this article, unique aspects of COVID-19 vaccine pharmacovigilance encountered by one MAH will be summarized. Full article

Objectives: Our objectives were to evaluate the safety of the simultaneous vaccination of Japanese encephalitis attenuated live vaccine (JEV-L) and measles, mumps, and rubella combined attenuated live vaccine (MMR) in children and to provide a reference for the implementation of the strategy of simultaneous vaccination with the two vaccines. Methods: The data of adverse events following immunization (AEFI) and vaccination for JEV-L and MMR from 2020 to 2023 were extracted through the Guangdong Province Vaccine Distribution and Vaccination Management Information System and the Chinese National AEFI Information System (CNAEFIS). The inclusion criteria were that children were born after 1 October 2019, and received the first dose of JEV-L or MMR after 1 June 2020, in accordance with the starting age for vaccination (8 months). The study used the number of vaccine doses as the denominator to calculate and compare the reporting rates of cases and calculated the relative risk (RR) of adverse reactions and the 95% confidence interval (CI). Results: In Guangzhou, a total of 214,238 doses of JEV-L were administered to children. JEV-L and MMR were co-administered in 464,009 doses, and MMR was administered separately in 241,150 doses. The overall reporting incidence rates of AEFI (per 100,000 doses) for JEV-L, the simultaneous vaccination group, and MMR were 11.20, 53.02, and 60.96, respectively. Among children aged 8 months in Guangzhou, 57.98% (463,512/799,423) received the simultaneous administration of JEV-L and MMR. In the reported AEFI events, general reactions accounted for 87.50% in the JEV-L group, 88.21% in the simultaneous vaccination group, and 89.80% in the MMR separate group. The incidence rates of common adverse reactions were 9.80, 46.7, and 54.74, respectively. The incidence rates of rare adverse reactions were 0.93, 3.88, and 2.90, respectively. The reporting incidence rates of fever ≥38.6 °C after vaccination were 4.20, 16.16, and 17.83 for the JEV-L separate group, simultaneous vaccination group, and MMR separate group, respectively. There was a significant difference between the simultaneous vaccination group and the JEV-L separate group (RR = 3.848, 95% CI = 1.927, 7.683), while no significant difference was found compared with the MMR separate group (RR = 0.906, 95% CI = 0.623, 1.318). The simultaneous vaccination group showed no significant differences in the reporting incidence rates of local redness and induration compared with the two separate vaccination groups (RR = 1.385, 95% CI = 0.144, 13.315; RR = 0.390, 95% CI = 0.087, 1.743; RR = 0.520, 95% CI = 0.033, 8.314). No significant differences were found in the incidence rates of rare adverse reactions such as maculopapular rash, urticaria, and thrombocytopenic purpura. Conclusions: The AEFI reporting incidence rate for the first dose of the simultaneous vaccination of JEV-L and MMR in 8-month-old children in Guangzhou is between the rates of the two separate groups. Compared with the MMR separate group, the simultaneous vaccination group does not increase the risk of adverse reactions. Full article

Objective: The aim of this study was to investigate a possible relationship between the time to onset (TTO) of adverse events following immunization (AEFIs) and recall bias and to compare it between AEFIs of COVID-19 vaccines reported though the spontaneous reporting system (SRS) and those from a cohort event monitoring (CEM) study. Methods: A retrospective study comparing TTO patterns of AEFIs of four COVID-19 vaccines from the SRS and those from a CEM study was performed. Reports concerning AEFIs related to COVID-19 vaccination were used for the study. TTO patterns were stratified for vaccination dose number, perceived burden of the AEFI, and for being pre-defined. Additionally, since menstrual disorders received much media attention, their effect on the TTO pattern was investigated for SRS reports only. Results: A total of 160,613 reports from the SRS and 19,979 from the CEM, containing 755,647 and 103,703 AEFIs, respectively, were included. For AEFIs with a short TTO, no differences in TTO patterns were observed. However, the median TTO for AEFIs from the SRS was lower with increasing TTO duration. There were differences in both median TTO and time to reporting for AEFIs reported before and during episodes of media attention, but no correlation between the two could be found. Conclusions: Based on the performed TTO analyses, recall bias does not seem to be more evident in SRS compared to CEM studies for AEFIs with a short TTO. For AEFIs with a longer TTO, this may be more pronounced. Full article

Background: The Haemophilus influenzae type b (Hib) vaccination has well-established safety and efficacy in preventing Hib and reducing related morbidity and mortality worldwide. China has a high disease burden of Hib yet a low coverage rate of Hib vaccines and remains the only WHO member country not including the Hib vaccine in its National Immunization Program (NIP), partly due to insufficient surveillance data on its safety. This study analyzed all adverse events following immunization (AEFIs) after Hib monovalent vaccination in Zhejiang Province from 2017 to 2023 to provide evidence for formulating relevant immunization strategies. Methods: Hib vaccine-related AEFIs in Zhejiang Province from 1 January 2017, to 31 December 2023, were collected through the Chinese National AEFI Information System (CNAEFIS) for a descriptive epidemiological analysis. Results: From 2017 to 2023, a total of 1740 Hib vaccine-related AEFIs were reported (incidence rate: 63.01/100,000 doses) (95%CI: 60.12/100,000 doses–66.04/100,000 doses), including 1577 common adverse reactions (57.10/100,000 doses) (95%CI: 54.35/100,000 doses–59.99/100,000 doses), 139 rare adverse reactions (5.03/100,000 doses) (95%CI: 4.26/100,000 doses–5.94/100,000 doses), and 24 coincidental events (0.87/100,000 doses) (95%CI: 0.58/100,000 doses–1.29/100,000 doses). Most of the AEFIs were common adverse reactions that manifested mainly as fever, injection site redness and swelling, and crying. AEFIs were more likely to occur in male participants under the age of one, in summer and autumn, and during the booster immunity stage. The top three regions with the highest reported incidence rates of AEFIs were Jiaxing City (86.61/100,000 doses) (95%CI: 74.44/100,000 doses–100.77/100,000 doses), Hangzhou City (81.29/100,000 doses) (95%CI: 72.56/100,000 doses–91.07/100,000 doses), and Taizhou City (66.62/100,000 doses) (95%CI: 58.24/100,000 doses–76.21/100,000 doses). Conclusions: Our findings provide preliminary evidence of the safety profile of the Hib vaccine at a provincial level, which adds further support for its broader implementation in other provinces. Future multi-center studies are needed to construct a comprehensive vaccine evaluation framework and make multi-criteria decisions on the feasibility of incorporating the Hib vaccine into China’s NIP. Full article

Adverse events following immunizations (AEFIs) with recombinant zoster vaccine (RZV) are underexplored in fragile populations. This study aims to assess incidence, duration, and characteristics of AEFIs, focusing on the impact of sex, age, and prior Herpes Zoster (HZ) infection in a frail population, including solid organ transplant recipients. We conducted an observational study on patients receiving RZV, and AEFIs were classified as local or systemic and analyzed for incidence, duration, and patterns across groups. We showed that females had a higher incidence of AEFIs (p = 0.02), both local and systemic symptoms, such as swelling +/− redness at the site of injection and fatigue, after the first and second doses. Younger adults experienced more systemic reactions, while older adults reported more local events (e.g., redness and swelling, p = 0.01). Moreover, patients with previous HZ infection exhibited a higher incidence of AEFIs after the second dose (68% vs. 38%, p = 0.001). In conclusion, sex, age, and clinical history significantly influenced AEFI incidence and manifestations. Therefore, it is important to personalize vaccination strategies in frail populations, by tailored administration and monitoring plans, especially in females and individuals with prior HZ infection, to improve vaccine safety and patient outcomes. Full article

Background: Despite adverse events following immunization (AEFI) being well described in vaccine trials, there is a need to produce more real-world data on events supposedly attributed to vaccination against COVID-19. This study aims to estimate the prevalence of AEFI in the first dose of COVID-19 vaccines in the state of Brazil and to verify whether such events differ among the types of vaccines offered in this country. Methods: A population-based study using linked administrative data on vaccine registry and adverse events following immunization in 2021 and 2022. The study included 10,169,378 individuals aged 18 or over who lived in Bahia and received the first dose of COVID-19 vaccines. We calculated AEFI prevalence and verified differences among vaccines by logistic regression to estimate crude and adjusted by sex and age group prevalence ratio (PR). Results: The prevalence of AEFI was 74.3 per 100,000 doses applied, with a higher rate of nonserious events, mainly following the ChAdOx1-S. More than two-thirds of these adverse effects occurred in women, and almost half were between 30 and 49 years old. The individuals who received ChAdOx1-S had a 125% higher prevalence than those who received CoronaVac. Those who received BNT162b2 and Ad26.COV2.S had a 71% and 58%, respectively, lower prevalence of AEFI than those who received CoronaVac. Conclusions: The use of vaccines against COVID-19 has proven to be positive and effective in combating SARS-CoV-2, significantly reducing morbidity and mortality from the disease. We cannot deny the presence of adverse events in the context of vaccination. However, the vaccines have proven to be safe and reliable. The results of this study offer relevant data that can contribute to the qualification of AEFI pharmacovigilance in Brazil and worldwide. Full article

Background: China has a high incidence rate of varicella yet a low coverage rate of the varicella vaccine (VarV), with safety concerns being a leading cause of the lack of vaccination willingness. This study aimed to describe VarV-related adverse events following immunization (AEFIs) and analyze their characteristics in Zhejiang, China, 2020–2022. Methods: VarV-related AEFIs in Zhejiang Province from 1 January 2020 to 31 December 2022 were collected through the Chinese National AEFI Information System (CNAEFIS) for a descriptive epidemiological analysis. Results: From 2020 to 2022, a total of 1477 VarV-related AEFI cases were reported (incidence rate: 34.79/100,000). The three most frequently reported clinical symptoms of common adverse reactions were fever, redness, and induration at the vaccination site. The distribution of VarV-related AEFIs varied significantly by age, dose, severity, and season. VarV-related AEFIs were more likely to be non-severe adverse events that occurred in the summer and winter seasons following the first dose of vaccine and among those under 3 years old. The top three regions with the highest incidence rates were Lishui City (59.53/100,000), Quzhou City (41.05/100,000), and Jinhua City (40.43/100,000). Most of the cases achieved full recovery without treatment (96.21%), and the rest were successfully treated without any sequelae. Conclusions: VarV demonstrates a safe profile in Zhejiang Province. Most VarV-related AEFIs are common reactions without requiring treatment, and the rates of rare and severe AEFIs remain low. Consistent monitoring, investigation, and diagnosis are needed to guide future VarV research and vaccination strategy adjustment. Our findings call for more policy changes, such as integrating VarV into China’s National Immunization Program and conducting more trials to evaluate the safety and effectiveness of VarV. Full article

Background/objectives: Coronavirus-19 (COVID-19) vaccines represent a significant milestone in the fight against coronavirus disease. Ongoing post-marketing surveillance and research are crucial for ensuring vaccine safety and effectiveness, aiding public health planning. Methods: Our retrospective cohort study included Albertans five years and older and vaccinated with at least one dose of an approved COVID-19 vaccine between 14 December 2020 and 30 April 2022. This epidemiological study aimed to determine the incidence of reported adverse events following immunization (AEFI) in Alberta and identify associated risk factors. Results: The study included 3,527,106 vaccinated Albertans who met the study inclusion criteria. A total of 2541 individuals (72.0 per 100,000) reported an AEFI, with 2759 adverse events, most of which occurred following the first dose of vaccine and within the first week post-vaccination. Of these, 70.4% were female, and the highest incidence was in the 35–54 age group. Given that mRNA vaccines were predominantly administered across Canada, we report AEFI rates (per 100,000 doses) for the mRNA vaccine brands at 27.7 for Pfizer and 40.7 for Moderna. Allergic events were the most frequently reported AEFI, followed by adenopathy. Logistic regression analysis indicated that sex (with females at higher risk), presence of comorbidities, days to symptom onset, vaccine type (mRNA vs. mixed doses), and the number of doses were significant factors associated with an AEFI event. Conclusions: Our study provides valuable information to guide policies surrounding COVID-19 vaccination. While the risk of serious adverse events was low in the population-based sample, further research is warranted to identify and investigate other possible risk factors that are still unknown. Full article

Objectives: This study aimed to evaluate the safety profile of the recombinant zoster vaccine (RZV) after its marketing in China. Methods: We present a descriptive analysis and safety signal assessment of adverse events following immunization (AEFI) associated with RZV between September 2020 and December 2023. The descriptive data collected includes demographic characteristics and the classification of characteristics of AEFI cases, while vaccine safety signal assessment was evaluated using the reporting odds ratio (ROR). Results: In total, we documented 275 AEFI cases following RZV vaccination, with a reporting rate of 76.22/10,000 doses administered. Notably, only one case was classified as serious, and the reporting rates were significantly higher among females, individuals aged 50–59 years, and those residing in rural areas. Furthermore, the reporting rate for the first dose exceeded that for the second dose. Among the reported AEFI cases, 98.91% were attributed to vaccine product-related reactions, and 97.45% were initially reported by either the vaccine recipient or their guardians. The interval between vaccination and symptom onset was predominant within 3 d after vaccination. The disproportionality analysis identified five positive signals—fever (37.5–38.5 °C), injection site reactions greater than 5 cm, pain, Henoch Schönlein purpura (HSP), and swelling—which suggests a stronger association with the RZV than the expected threshold. Conclusion: In summary, RZV demonstrated a favorable safety profile. However, continued monitoring and research on the long-term safety implications of RZV are needed. Full article

Background: The COVID-19 pandemic necessitated rapid and widespread vaccination efforts, which proved critical in reducing the severity and mortality of the virus. However, the interplay between vaccinations, pre-existing skin conditions, and other comorbidities still needs to be explored. This study investigated the occurrence and severity of adverse events following immunization (AEFIs) with COVID-19 vaccines in individuals with chronic skin diseases and comorbidities within a Central European cohort. Methods: An anonymous online survey was conducted between May 2022 and February 2023, targeting students and employees of universities in Wrocław, Poland. A total of 513 respondents were analyzed, focusing on AEFIs following the first, second, and third doses of COVID-19 vaccines and the effects of COVID-19 on conditions such as atopic dermatitis, psoriasis, vitiligo, acne vulgaris, rosacea, and various comorbidities. Results: COVID-19 vaccination effectively protected against severe disease across all doses. The analysis revealed no significant impact of either COVID-19 infection or vaccination on the course of selected skin diseases and comorbidities. The reporting of AEFIs to the Sanitary Inspection was notably low. The Moderna and Pfizer mRNA-based vaccines were associated with a higher reported number of AEFIs, particularly after the second and third doses, compared to AstraZeneca, which exhibited fewer adverse events after subsequent doses. Conclusions: COVID-19 vaccination is both safe and effective, even in patients with pre-existing skin conditions and comorbidities. Vaccine selection may benefit from considering individual health profiles, and better reporting of AEFIs is needed to enhance vaccine safety monitoring. Full article

Background: Post-marketing surveillance is crucial for gathering data on vaccine reactogenicity, enhancing public trust in immunization, and promoting vaccine uptake. This study aims to characterize adverse events following immunization (AEFIs) and estimate the incidence rates of adverse reactions (ARs) associated with vaccines included in Taiwan’s Expanded Program on Immunization (EPI). This study utilizes data from Taiwan’s Vaccine Injury Compensation Program (VICP). Methods: Vaccine injury claims submitted to the VICP between 2014 and 2019 were analyzed. ARs were defined as AEFIs adjudicated as “related” or “indeterminate” by the VICP committee. Data on the annual number of vaccine doses administered were obtained from the Taiwan CDC, which helped calculate the AR incidence rates. Results: A total of 491 AEFI claims were reviewed, with 327 (66.6%) categorized as ARs. The AEFIs were mainly associated with the Bacillus Calmette–Guérin (BCG) vaccine (43.4%) and the seasonal influenza vaccine (22.0%). Most EPI vaccines demonstrated low AR incidence rates, ranging from 1.68 to 13.6 per million doses, with the exception of BCG, which exhibited 162.5 ARs per million doses. Shifting BCG immunization from below 5 months to at least 5 months reduced osteomyelitis incidence significantly, from 41.4 to 7.9 (p = 0.0014), but increased abscess and lymphadenitis cases. Conclusions: EPI vaccines in Taiwan are highly safe, with minimal AR incidences in the general population. The BCG vaccine remains an exception, occasionally causing severe ARs like osteomyelitis. Adjusting the immunization schedule to an older age may mitigate some of these adverse effects. Full article

Underreporting is the main limitation of spontaneous reporting systems. This cohort-event monitoring study aims to examine the potential of short message service (SMS)-based surveillance compared to traditional surveillance systems. Using VigiVax software, parents of vaccinated children aged two years or younger, in the period March 2021–May 2022, received a single SMS inquiry about adverse events following immunization (AEFI). Responses were collected, validated by health operators and integrated with the information on electronic immunization registries. AEFI reports were automatically submitted to the Italian Pharmacovigilance system. Among 254,160 SMS messages sent, corresponding to 451,656 administered doses (AD), 71,643 responses were collected (28.2% response rate), and 21,231 of them (8.3%) reported AEFI. After a seriousness assessment based on clinical criteria, 50 reports (0.24%) were classified as serious. Among these, a causality assessment identified 31 reports at least potentially related to the vaccination (RR: 6.86/100,000 AD). Febrile seizures following MMRV (measles, mumps, rubella, varicella) vaccination accounted for 11 of these 31 cases, with an incidence of 32 per 100,000 AD. No fatal outcomes were reported. Our findings support the highly favorable risk profile of pediatric vaccinations and the possibility to improve spontaneous reporting through the integration of digital technologies. Full article

Pharmacovigilance plays a central role in safeguarding public health by continuously monitoring the safety of vaccines, being critical in a climate of vaccine hesitancy, where public trust is paramount. Pharmacovigilance strategies employed to gather information on adverse events following immunization (AEFIs) include pre-registration data, media reports, clinical trials, and societal reporting. Early detection of AEFIs during clinical trials is crucial for thorough safety analysis and preventing serious reactions once vaccines are deployed. This review highlights the importance of societal reporting, encompassing contributions from community members, healthcare workers, and pharmaceutical companies. Technological advancements such as quick response (QR) codes can facilitate prompt AEFI reporting. While vaccines are demonstrably safe, the possibility of adverse events necessitates continuous post-marketing surveillance. However, underreporting remains a challenge, underscoring the critical role of public engagement in pharmacovigilance. This narrative review comprehensively examines and synthesizes key aspects of virus vaccine pharmacovigilance, with special considerations for specific population groups. We explore applicable legislation, the spectrum of AEFIs associated with major vaccines, and the unique challenges and perspectives surrounding pharmacovigilance in this domain. Full article