Adverse event reporting following immunization of hepatitis B vaccine: A 13-year review.

Hepatitis B vaccination is the most effective means of interrupting HBV transmission. Although the hepatitis B vaccine is very effective and safe, adverse events following immunization do occur and need to be reported so that problems can be identified and appropriate corrective action can be taken. Most of the research on AEFI focuses on the safety observation of newly used vaccines, and there are few long-term studies on AEFI of the hepatitis B vaccine. This study retrospectively analyzes the reporting rate, clinical symptoms, and onset time of AEFI of the hepatitis B vaccine in Quzhou from 2011 to 2023, and compares the differences in AEFI reporting rates between different types of hepatitis B vaccines, different vaccination ages, and different doses. The surveillance results show that from 2011 to 2023, the AEFI reporting rate of hepatitis B Vaccines in Quzhou was 17.55/100,000 doses. 98.73% of reported AEFI were non-serious. The types of AEFI reported were vaccine product-related reactions, immunization anxiety-related reactions, and coincidental events. 94.12% of vaccine product-related reactions occurred within 3 days, and the main symptoms were fever, local reactions at the injection site, and rash. The AEFI reporting rate of the CHO vaccine was higher than that of the yeast vaccines, and the probability of AEFI in children under 1 year of age receiving the hepatitis B vaccine was higher in the latter dose than in the previous dose. The 13-year-long AEFI surveillance provides reliable evidence of the safety of the hepatitis B vaccine.

An evaluation of the surveillance system for monitoring and reporting adverse events following immunization in Kebbi State, Northern Nigeria: a mixed method approach.

INTRODUCTION: Despite the benefits of periodic evaluation of the vaccine safety surveillance system, no formal assessment, to our knowledge, has been conducted in Nigeria. Hence, this study evaluated the surveillance system for adverse events following immunization (AEFI) to ascertain the system's functionality to inform vaccine safety considerations and guide communication strategies for demand generation. MATERIALS AND METHODS: The study employed a mixed-method approach. Survey questionnaires were administered to 274 routine immunization service providers in Kebbi State, Northern Nigeria, and data were analyzed descriptively using SPSS. In this study, 10 Key Informant Interviews and two Focus Group Discussions were conducted with senior officers and managers at sub-national and national levels within the immunization and surveillance landscape in Nigeria. The interview recordings were cleaned minimally, transcribed, and manually analyzed thematically. Finally, methodological triangulation was done to improve research rigor and provide a better understanding of the phenomena under investigation. RESULTS: Of the respondents, 201(73.4%) reported that the surveillance system can inform vaccine safety considerations while 170(62%) reported that the AEFI surveillance system can determine the magnitude of AEFI within the population. Further, 173(63%) reported that the surveillance system can provide timely feedback about causality assessment. However, 158(58%) of the respondents stated that the surveillance system is competent in informing communication strategies to improve immunization demand. Triangulation was done which showed dissonance in AEFI surveillance and vaccine safety considerations but partial agreement in immunization demand generation. Further, AEFI surveillance system attributes' triangulation revealed agreements (convergence) on simplicity and timeliness; partial agreements on acceptability, data quality, sensitivity, flexibility, and completeness; dissonance on representativeness and silence on stability, indicating a sub-optimal performance of the AEFI surveillance system in the study setting. Finally, the study unearthed some underlying health system factors impeding the AEFI surveillance system from fully fulfilling its objectives. CONCLUSION: The AEFI surveillance system in Northern Nigeria is well established but functioning sub-optimally. Based on the study findings, the capacity to provide information on vaccine safety exists but it is not robust enough to generate sufficient and convincing vaccine safety data and guide communication strategies for vaccine demand generation, especially for new vaccines and those under emergency authorization use.

Post-vaccine immune status surveillance of Covishield vaccine and associated AEFI in previously SARS-Cov-2 infected seropositive and seronegative population in Assam.

Background: COVID-19 an infectious disease caused by the SARS-CoV-2 virus, started in late 2019 and became a pandemic within a short period. To respond to the pandemic vaccines like Covishield, Covaxin, Sputnik V, Covovax, etc., were developed rapidly. However, there were raising concerns about the development of immunity as well as adverse events following vaccination. Objectives: To compare anti-SARS-CoV-2 IgG antibody titres at different time-points post-vaccination between baseline seropositive and seronegative groups and to assess the adverse events following the 1st dose of Covishield vaccine among adult beneficiaries attending vaccination centre in a tertiary care hospital of Upper Assam. Materials and Methods: Prospective Cohort study was conducted from July 2021 to June 2022 among adult beneficiaries receiving the Covishield vaccine. The oral questionnaire was used incorporating socio-demographic variables, and clinical profiles including co-morbidities and adverse events following vaccination. Data analysis was done by Microsoft Excel and SPSS. Results: Out of a total of 146 study participants, IgG estimation showed 61% as seropositive and the rest as seronegative. A total of 55.40% had minor adverse events, majority of them were females (53.08%) and 88.80% belonged to 18-59 years compared to 11.11% above 60 years of age. The majority (71.60%) did not have any co-morbidities and the major AEFI was NIL among the study participants. The study group had 61% seropositive previously infected. Conclusion: Covishield vaccination induces an immune response and 90% seroconversion is achieved after 1st dose (booster dose). Antibody titres of the seropositive group by natural infection of SARS-CoV-2 were higher than seronegative cohort seroconverted by vaccination. The AEFI observed were minor and can be commented as safer.

Safety Surveillance of Covishield Vaccine-Associated Adverse Events During the COVID-19 Pandemic: A Retrospective Longitudinal Study.

BACKGROUND: Adverse events following immunization (AEFI) must be reported and assessed to promote patient safety. This longitudinal study examined the nature and severity of adverse events reported after Covishield (Serum Institute of India, Pune, India) vaccine administration to North Indians in a tertiary care hospital. METHOD: A retrospective evaluation of adverse drug reactions (ADRs) reported after Covishield vaccine administration in our hospital over 18 months was conducted. The assessment was carried out to analyze the pattern of ADRs reported by individuals receiving the Covishield vaccine from January 2021 to June 2022. Data such as age, gender, category, dose administered, type of ADR, duration of the event, medical history, and outcome of the reactions were collected. Each reported adverse event was assessed individually. Causality was determined using the WHO-UMC causality assessment scale. The data were analyzed and are expressed as mean ± standard deviation and percentage. RESULTS: A total of 14,590 individuals were vaccinated at our study center from January 2021 to June 2022. During this period, 146 AEFIs (1.0%) were reported at our ADR monitoring center, Employees' State Insurance Corporation Medical College and Hospital (ESIC MCH), Faridabad, India. The majority of AEFIs were systemic, were reported after the first dose, and had an onset within 12 hours after vaccination. Fever, injection site pain, drowsiness, headache, vomiting, swelling, tenderness, and body aches were the most commonly reported adverse effects. No significant relationships were observed between the administered vaccine dose and sex, severity, duration of the event, or outcome. However, the incidence of adverse events was greater with the first vaccine dose than with the second dose. The possibility of serious or fatal adverse events was lowest in the general population and higher in the elderly with comorbidities. CONCLUSION: The data suggest that the Covishield vaccine had mild to moderate adverse effects on the study population. This pharmacovigilance study will complement safety data and aid in the benefit-risk analysis of adverse effects associated with the Covishield vaccine. Additionally, healthcare professionals should be encouraged to conduct further safety studies by establishing robust vaccine safety monitoring systems in hospitals. Continuing medical education and workshops should also be conducted to educate healthcare workers about active surveillance.

Safety of Adjuvanted Recombinant Herpes Zoster Virus Vaccination in Fragile Populations: An Observational Real-Life Study.

BACKGROUND: Vaccination is the most effective strategy for preventing infectious diseases and related complications, and proving its efficacy is crucial for its success and adherence, especially for newly introduced vaccines, such as adjuvanted recombinant herpes zoster virus vaccination (RZV). In this observational real-life study, we recorded adverse effects following immunization (AEFIs) after RZV administration in frail populations. METHODS: A total of 271 subjects underwent RZV at Vaccination Center, University Hospital "San Giovanni di Dio e Ruggi d'Aragona", Salerno, Italy. Most subjects were solid organ transplant recipients (kidney, 77.1%; liver, 4.8%). Demographics, clinical data, and AEFIs (type, duration, and medications used) were recorded. RESULTS: Overall, 37% of participants reported at least one AEFI following the first dose, predominantly pain at the injection site (60%), while 41% did so after the second dose (pain at the injection site in 62% of cases). Medications were more frequently used for AEFI treatment after the second dose (28%) rather than after the first dose (13%) (p = 0.01). After stratification by sex, females experienced AEFIs more frequently than males, particularly local skin reactions. CONCLUSIONS: Our study added evidence of safety and tolerability of the adjuvanted recombinant RZV in frail adults.

Adverse events following immunization (AEFI) with fractional one-fifth and one-half doses of yellow fever vaccine compared to full dose in children 9-23 months old in Uganda, 2019-2020 - Preliminary report.

BACKGROUND: In 2016, the World Health Organization recommended that a fractional dose of yellow fever (YF) vaccine could be used in persons 2 years of age or older in response to an emergency that resulted in a global shortage of available YF vaccine. However, this recommendation did not extend to the youngest age group licensed for YF vaccine because there were no published data on the use or safety of fractional dose YF vaccination in children aged 9-23 months. We conducted a single-blind randomized controlled trial, comparing the immunogenicity and safety of fractional one-fifth and one-half doses of Bio-Manguinhos 17DD YF vaccine with full dose in children aged 9-23 months old in Uganda. In this paper, we present the interim analysis on safety. METHODS: Children aged 9-23 months presenting for routine well-child services were recruited for inclusion at one of three study sites. We collected data during March 26, 2019-August 31, 2020, on all adverse events following immunization (AEFI) during active surveillance for 28 days post-vaccination using multiple collection tools including a diary card with an objective measurement of fever. An independent team from the Uganda national AEFI Committee investigated and classified serious AEFI (SAE) according to Brighton Collaboration Criteria. RESULTS: Among 1053 enrolled children, 672 (64%) were reported to have a non-serious AEFI (NSAE) and 17 (2%) were reported to have a SAE. The most common AEFI were diarrhoea, fever, and rash, each reported by 355 (34%), 338 (33%), and 188 (18%) participants, respectively. Among 17 participants with SAE, eight were reported to have had seizures and five were hospitalised for seizures or other causes (respiratory symptoms, gastrointestinal illness, malaria). Four SAEs (deaths) occurred >28 days after vaccination. There were no reported cases of pre-specified or vaccine-related SAEs. We observed no significant difference in frequency or severity of adverse events among the study groups. CONCLUSIONS: Using comprehensive active surveillance monitoring, we did not identify any unexpected safety concerns among children aged <2 years receiving YF vaccination, including with the fractional doses. Although we identified a high number of both serious and non-serious AEFI, none were determined to be causally related to YF vaccination. These results provide evidence for the safety of fractional dose YF vaccination among children aged 9-23 months.

Patient-reported outcomes of adverse events after COVID-19 vaccination in Nigeria: A mixed methods study.

BACKGROUND: Adverse events following immunization (AEFIs), especially if serious, may impact vaccine recipients' quality of life and financial well-being and fuel vaccine hesitancy. Nigeria rolled out COVID-19 vaccination in 2021 with little known about the impact of AEFIs on an individual's quality of life. No study in Africa has explored the health and financial impact of AEFIs. We explored patient-reported outcomes (PROs) of adverse events after COVID-19 vaccination and documented the lived experiences of those with serious AEFIs to understand the effect on their health, financial well-being, and attitude to future vaccinations. METHODS: We conducted a convergent mixed-methods study using the RAND 36-item health survey and in-depth interviews to collect PROs on vaccine recipients in Nigeria. Eight health scale scores and two summary composite scores were used to measure the health-related quality of life outcomes from the survey and inductive analysis was used to identify themes from the interview scripts. The results of both studies were integrated in a joint display to highlight areas of concordance. RESULTS: In total, 785 survey responses were analyzed (53% females, 68% aged 18-30 years). Responders reporting an AEFI were 58%, of whom 62% received the first dose only. Younger age and first vaccine dose (p < .001 respectively) were associated with experiencing an AEFI. Not reporting an AEFI was associated with better quality of life, measured as higher scores on all eight SF-36 Health scales and the physical and mental component summary scores. All six interviewees with serious AEFIs experienced physical, mental, and financial distress. Some expressed a strong negative attitude toward future COVID-19 vaccinations but not toward vaccines for routine immunization. CONCLUSION: AEFIs negatively impact the health and financial well-being of affected individuals and their attitude to future vaccinations, especially if serious. Understanding the impact of AEFIs on people is important and should inform future policies and interventions. The results of our study can inform policy and planning for future mass vaccination campaigns in LMICs.

Suspected Diphtheria Toxoid and Tetanus Toxoid (dTdap) Booster Vaccine-Induced Postural Orthostatic Tachycardia Syndrome (POTS).

We describe a case of a 40-year-old South Asian woman who presented with symptoms suggestive of postural orthostatic tachycardia syndrome (POTS) following a diphtheria toxoid and tetanus toxoid (dTdap) booster vaccination administered one week prior. The patient's POTS responded favorably to treatment with low-dose fludrocortisone and ivabradine. Clinicians should maintain a high index of suspicion for POTS as a possible vaccine adverse event (VAE) post-dTdap booster inoculation and be aware of appropriate management strategies.

Assessment of safety and adverse events following COVID-19 vaccination and their predictors in first 30 days among healthcare workers of a tertiary care teaching hospital in North India.

Background: The COVID-19 vaccines were rolled out as an emergency measure, with an expedited approval to contain the pandemic. The objective of this study was to assess the incidence, pattern and severity of AEFIs reported following COVID-19 vaccination and their predictors among the healthcare workers. Materials and methods: A prospective cohort study enrolling healthcare workers of a tertiary care Institute in North India receiving COVISHIELD™ from February to May 2021 was carried out to assess the incidence, pattern and severity of AEFI over the next 30 days. Both active and passive surveillance methods were used for AEFI recording. Bivariate analysis was performed to ascertain the predictors of AEFIs. Results: A total of 836 healthcare workers who received the first dose of COVISHIELD™ were included in the study of which 201 (24.0 %) experienced one or more AEFIs. Majority of AEFIs were of minor grade (99.8 %) and resolved spontaneously. Majority (96.0 %) had onset of the AEFIs within 48 hrs of vaccination. Serious AEFIs, leading to hospitalization was noticed in 2(0.2 %) participants, both females, with suspicion of immunization stress related response (ISRR). Both of them recovered without any sequelae. No deaths were recorded. Factors found to be significantly associated with the occurrence of AEFIs in the participants were female gender (p = 0.02), monthly income > 20,000 INR (p = 0.007), presence of any chronic illness (p < 0.0001), history of allergic reaction to any drug/vaccine (p = 0.01), history of COVID-19 infection (p < 0.00002) and history of hospitalization due to COVID-19 (p < 0.0002). Conclusion: Majority of the AEFIs observed were of minor grade with spontaneous resolution of the symptoms indicating safety and well tolerability of the vaccine. Female gender, higher income, history of allergy and co-morbidities, history of COVID-19 infection and history of hospitalization were found to be major predictors for the development of adverse events and require more watchful vaccination.

Adverse Events of COVID-19 Vaccines in the United States: Temporal and Spatial Analysis.

BACKGROUND: The COVID-19 pandemic, caused by SARS-CoV-2, has had a profound impact worldwide, leading to widespread morbidity and mortality. Vaccination against COVID-19 is a critical tool in controlling the spread of the virus and reducing the severity of the disease. However, the rapid development and deployment of COVID-19 vaccines have raised concerns about potential adverse events following immunization (AEFIs). Understanding the temporal and spatial patterns of these AEFIs is crucial for an effective public health response and vaccine safety monitoring. OBJECTIVE: This study aimed to analyze the temporal and spatial characteristics of AEFIs associated with COVID-19 vaccines in the United States reported to the Vaccine Adverse Event Reporting System (VAERS), thereby providing insights into the patterns and distributions of the AEFIs, the safety profile of COVID-19 vaccines, and potential risk factors associated with the AEFIs. METHODS: We conducted a retrospective analysis of administration data from the Centers for Disease Control and Prevention (n=663,822,575) and reports from the surveillance system VAERS (n=900,522) between 2020 and 2022. To gain a broader understanding of postvaccination AEFIs reported, we categorized them into system organ classes (SOCs) according to the Medical Dictionary for Regulatory Activities. Additionally, we performed temporal analysis to examine the trends of AEFIs in all VAERS reports, those related to Pfizer-BioNTech and Moderna, and the top 10 AEFI trends in serious reports. We also compared the similarity of symptoms across various regions within the United States. RESULTS: Our findings revealed that the most frequently reported symptoms following COVID-19 vaccination were headache (n=141,186, 15.68%), pyrexia (n=122,120, 13.56%), and fatigue (n=121,910, 13.54%). The most common symptom combination was chills and pyrexia (n=56,954, 6.32%). Initially, general disorders and administration site conditions (SOC 22) were the most prevalent class reported. Moderna exhibited a higher reporting rate of AEFIs compared to Pfizer-BioNTech. Over time, we observed a decreasing reporting rate of AEFIs associated with COVID-19 vaccines. In addition, the overall rates of AEFIs between the Pfizer-BioNTech and Moderna vaccines were comparable. In terms of spatial analysis, the middle and north regions of the United States displayed a higher reporting rate of AEFIs associated with COVID-19 vaccines, while the southeast and south-central regions showed notable similarity in symptoms reported. CONCLUSIONS: This study provides valuable insights into the temporal and spatial patterns of AEFIs associated with COVID-19 vaccines in the United States. The findings underscore the critical need for increasing vaccination coverage, as well as ongoing surveillance and monitoring of AEFIs. Implementing targeted monitoring programs can facilitate the effective and efficient management of AEFIs, enhancing public confidence in future COVID-19 vaccine campaigns.

Adverse events following immunization of co- and separate administration of DTaP-IPV/Hib vaccines: A real-world comparative study.

To fully understand the safety of DTaP-IPV/Hib vaccination, we evaluated the differences between DTaP-IPV/Hib co-administration and separate administration of the DTaP, IPV and Hib vaccines (DTaP+IPV+Hib) based on adverse events following immunization (AEFI). All AEFI reported in Hebei Province, China, between 2020 and 2022 were included in this study. The risk difference (RD%), relative risk (RR), and Chi-square value were used to compare the differences in reported rates of AEFI between the DTaP-IPV/Hib and DTaP+IPV+Hib groups. From 2020 to 2022, 130 AEFI cases were reported in Hebei Province after DTaP-IPV/Hib vaccination, corresponding to an AEFI reported rate of 66.9/million doses, which was significantly lower than that for DTaP+IPV+Hib (9836 AEFI with a reported rate of 637.8/million doses). The overall reported rate of non-severe AEFI for DTaP+IPV+Hib vaccines was 9.5 times that of DTaP-IPV/Hib vaccination [95% confidence interval (CI): 8.0, 11.3]. Meanwhile, the reported rate of AEFI among infants aged 0-1 y was 9.8 times higher for DTaP+IPV+Hib than for DTaP-IPV/Hib (95% CI: 8.2, 11.7). DTaP+IPV+Hib vaccination also resulted in higher risks of high fever, localized redness and swelling, localized induration, and allergic rash compared with DTaP-IPV/Hib vaccination. The risk of AEFI, which were mostly mild reaction, was higher after vaccination with DTaP+IPV+Hib than after DTaP-IPV/Hib vaccination.

Surveillance of adverse events following immunisation in Australia, COVID-19 vaccines, 2021.

Abstract: This report summarises Australia's spontaneous (passive) surveillance data for adverse events following immunisation (AEFI) for coronavirus disease 2019 (COVID-19) vaccines in 2021 reported to the Therapeutic Goods Administration (TGA). The TGA strongly promoted and facilitated adverse event reporting in preparation for, and during, the COVID-19 vaccine rollout as a core component of the most intensive vaccine safety monitoring ever conducted in Australia. There were 111,348 AEFI reports for COVID-19 vaccines administered in 2021, an annual AEFI reporting rate of 271.4 per 100,000 doses of COVID-19 vaccines administered to people aged ≥ 12 years. The annual AEFI reporting rate for non-COVID-19 vaccines in 2021 was 30.6 per 100,000 doses administered to people of all ages. Overall, the most frequently reported symptoms were headache, adverse events classified as 'gastrointestinal nonspecific symptoms and therapeutic procedures', myalgia, pyrexia and fatigue, which were consistent with common expected adverse events following COVID-19 vaccines used in Australia. The most commonly reported adverse events of special interest were myocarditis and/or pericarditis, followed by thrombosis and thromboembolism, and anaphylaxis. Of all COVID-19 vaccine AEFI reports, 762 (0.7%) included a fatal outcome, of which over 80% were in people aged ≥ 60 years. Thirteen deaths reported in 2021 were assessed as likely to be causally linked to vaccination. This report confirms the value of spontaneous post-marketing vaccine pharmacovigilance, especially in the context of new vaccines using novel vaccine technologies and near whole-of-population pandemic vaccination programs. The most frequently reported AEFI for COVID-19 vaccines were common, mild and temporary (lasting 1 or 2 days), and consistent with clinical trial and active surveillance data. Ongoing safety monitoring detected rare, unexpected conditions, such as myocarditis/pericarditis and thrombosis with thrombocytopenia syndrome (TTS), which were investigated and confirmed as safety signals, resulting in changes to vaccine recommendations and product information. The outcomes of TGA monitoring were published in weekly vaccine safety reports. Overall, COVID-19 vaccine safety monitoring provided critical information on the risks of vaccine related adverse events that enabled decisionmakers to undertake informed risk-benefit assessments.

Surveillance of adverse events following immunisation in Australia annual report, 2021.

Abstract: This report summarises Australia's spontaneous surveillance data for adverse events following immunisation (AEFI) for 2021 reported to the Therapeutic Goods Administration (TGA) and describes reporting trends over the 22-year period 1 January 2000 to 31 December 2021. This report excludes AEFI reports featuring pandemic coronavirus disease 2019 (COVID-19) vaccines, which are reported separately. There were 3,452 AEFI reports for non-COVID-19 vaccines administered in 2021, an annual AEFI reporting rate of 13.4 per 100,000 population compared with 14.9 per 100,000 population in 2020. This small decrease in the AEFI reporting rate in 2021 could potentially be related to an increased focus on COVID-19 vaccines and related AEFI, which are not included in this report. AEFI reporting rates for individual vaccines in 2021 were similar to 2020, as were the most commonly reported adverse events. Of the six deaths following vaccination in 2021 reported to the TGA, none were found to have a causal relationship with vaccination.

Side effects of CoronaVac® COVID-19 vaccination: Investigation in North Jakarta district public health center communities in Indonesia.

Background: The decreasing prevalence of COVID-19 has highlighted the value of vaccinations. CoronaVac® vaccine was one of the most widely used vaccines in Indonesia, in other Southeast Asian countries, as well as in Latin America. However, to date the safety and side effect profiles of CoronaVac® vaccine among the Indonesian population have not been reported. Objective: In this study, the CoronaVac® safety profiles were determined in a community of a public health center in North Jakarta, Indonesia. Method: This is a descriptive cross-sectional questionnaire-based study on vaccine side effects as recorded in the yellow form (MESO). Patients (n = 300) who received CoronaVac® vaccinations between July and August 2021 were enrolled. SPSS was used to analyze the descriptive data. Results: Most respondents were women (72.7 %) between the ages of 17 and 21 years. A significantly (p = 0.009) positive correlation was established between the vaccine side effects (namely pain at the injection site) with the female gender. Other side effects such as fatigue (p = 0.034) and headache (p < 0.001) were also correlated with disease comorbidity. Conclusion: Overall, the side effects following the first and the second doses were generally mild and included fever, pain in the injection area, fatigue, headache, drowsiness, diarrhea, cough, and nausea. Regarding vaccine efficacy, CoronaVac® confers better protection following the second dose administration where the percentage of respondents affected with COVID-19 (26.7 %) decreased to only 20.3 % following the second dose.

Adverse Events Following COVISHIELD and VERO CELL Vaccination Campaigns Against COVID-19.

BACKGROUND: Vaccination against COVID-19 for Nepalese was initiated in January 2021 for various age groups. People were anxious about receiving the vaccines and were concerned about the safety profile of the vaccine they received. In this study, we have tried to observe the Adverse Events Following Immunization of two different vaccines namely COVISHIELD (ChAdOx1 nCOV-19) and VERO CELL (CZ02 strain), used in different phases of vaccination by the government of Nepal. METHODS: We conducted a cross-sectional study among people who received COVID-19 vaccines in this study using a self-administered questionnaire.  Data was cleaned and then exported to IBM SPSS v.20 for analysis, Chi-square test was used to see the association between different variables and a p-value<0.05 was considered statistically significant. RESULTS: Out of 303 respondents, all had received the first and 270 participants had received the second dose of the COVID-19 vaccine, among which, 133 (43.89%) reported at least one side effect after the first dose of vaccination while 58 (21.48%) had self-reported side effects after the second dose of vaccination. Seventeen percent of the respondents had COVID-19 infection within the past 3 months before receiving COVID-19 vaccine. Three percent of participants had re-infection with COVID-19 after receiving the first or the second dose of the COVID-19 vaccine. Among participants who experienced adverse events, 42% and 62.1% of participants experienced mild adverse events following the first dose and second dose of the vaccine, respectively.  Conclusions: The adverse events following immunization for both vaccines after both doses of vaccination were quite low, with 43.89% of participants reporting side effects after the first dose and 21.48% of participants reporting side effects after the second dose. Adverse events were most frequently reported within 24 hours of vaccination and were mostly mild. There was no statistical significance of adverse events between both vaccines.

Canadian vaccine safety surveillance reports following immunization with seasonal influenza vaccines, 2021-2022.

Background: Seasonal influenza vaccines (SIV) authorized for use in Canada have all undergone rigorous regulatory assessments for safety and effectiveness. Serious adverse events following immunization (AEFI) can occur, though they are rare. Continuous safety surveillance of vaccines during the post-marketing phase is a critical component of vaccination programs. This enables the detection of rare, late onset, or unexpected adverse events. An updated safety summary following the introduction of any new vaccines and/or formulations to immunization programs is necessary for refining the risk-benefit profile of a specific vaccine and maintaining public confidence. Here we provide an updated safety summary for SIVs distributed during the 2021/2022 influenza season from AEFI reports submitted to the Canadian Adverse Event Following Immunization Surveillance System (CAEFISS) and the Canadian Vigilance Database (CVD). Methods: We searched CAEFISS and CVD for individuals who were vaccinated with a SIV between October 1, 2021, and March 31, 2022. Descriptive statistics were calculated, including median age of vaccinated individuals, vaccines co-administered with SIV, and the most frequently reported AEFIs. Crude AEFI reporting rates were calculated by severity of the AEFI report, and SIV-type using doses distributed data. Medical reviews were conducted for reports including death, serious events (or outcomes) after SIV were administered alone, and selected adverse events (i.e., anaphylaxis, Guillain-Barré syndrome, febrile seizures, oculo-respiratory syndrome). Disproportionality analysis was used to identify potential safety signals among SIV and AEFI pairs. Results: There were 448 AEFI reports, with most AEFI classified as non-serious events (84.2%). The majority of reports described vaccination in adults at least 65 years of age (38.6%). The most frequently reported AEFIs were vaccination site pain, urticaria, pyrexia and rash. Medical review of AEFI reports did not find any evidence that reported deaths were related to vaccination with SIV. Among serious reports, nervous system disorders were the most commonly reported medical conditions. A higher number of events related to vaccination errors were also identified using disproportionality analysis. Conclusion: Findings from our analysis of reports to CAEFISS and CVD following vaccination with SIV are consistent with the known safety profile of SIVs distributed during the 2021/2022 influenza season. The majority of reports were non-serious with the most common AEFI symptoms occurring at the vaccination site or systemic symptoms that were self-limiting. The majority of vaccination error reports involved the administration of the vaccine at an inappropriate site, although no serious AEFIs were reported.

Surveillance for adverse events following immunization with DTaP-containing combination vaccines in Linping, China, 2019-2022.

Background: The DTaP-Hib and DTaP-IPV/Hib combination vaccine can be used as a substitute for the diphtheria, tetanus, and acellular pertussis combined vaccine (DTaP). We aimed to evaluate the safety of multi-component vaccines containing DTaP by analyzing the reporting rates and characteristics of adverse events following immunization (AEFIs) in Linping District during the years 2019 to 2022. Methods: We obtained data of AEFI and vaccination from the National AEFI Surveillance System of China and Zhejiang Municipal Immunization Information Management System, respectively, during 2019-2022 for a descriptive, epidemiological analysis. Results: The total number of AEFI reported following vaccinations with DTaP-containing combination vaccines was 802 in Linping District from 2019 to 2022. The overall reporting rates of AEFIs following DTaP, DTaP-Hib, and DTaP-IPV/Hib vaccinations were 445.72 (537 cases), 536.29 (45 cases), and 306.13 (220 cases) per 100,000 doses in Linping District from 2019 to 2022, respectively. Only one case of a serious AEFI following DTaP vaccination, with a reporting rate of 0.83 per 100,000 doses. The composition ratio of vaccine product-related reactions for DTaP, DTaP-Hib, and DTaP-IPV/Hib were 99.81, 97.78, and 100.00%, respectively. The composition ratio of coincidental events for DTaP and DTaP-Hib were 0.19 and 2.22%, respectively. The reporting rates of total AEFIs for DTaP-IPV/Hib were lower than for DTaP. The reporting rate of local induration for DTaP-Hib was lower than for DTaP, and the reporting rates of local redness & swelling and local induration for DTaP-IPV/Hib were both lower than for DTaP. DTaP-IPV/Hib had a higher proportion of AEFIs in first quarter compared to DTaP. The reporting rate after the second dose of DTaP-Hib was higher than that of DTaP, and the reporting rates of AEFIs after the first dose and third dose of DTaP-IPV/Hib were lower than DTaP. Conclusion: The reported AEFIs to multi-component vaccines containing DTaP components during 2019-2022 in Linping District were mainly mild vaccine reactions. DTaP-containing combination vaccines demonstrated a good safety profile.

Intussusception and Other Adverse Event Surveillance after Pilot Introduction of Rotavirus Vaccine in Nam Dinh and Thua Thien Hue Provinces-Vietnam, 2017-2021.

Rotavin-M1 (POLYVAC) was licensed in Vietnam in 2012. The association of Rotavin-M1 with intussusception, a rare adverse event associated with rotavirus vaccines, and with adverse events following immunization (AEFI) have not been evaluated and monitored under conditions of routine use. From February 2017 to May 2021, we conducted a pilot introduction of Rotavin-M1 into the routine vaccination program in two provinces. Surveillance for intussusception was conducted at six sentinel hospitals. AEFI reports at 30 min and 7 days after vaccination were recorded. Among 443 children <12 months of age admitted for intussusception, most (92.3%) were children ≥ 6 months. Of the 388 children who were age-eligible to receive Rotavin-M1, 116 (29.9%) had received ≥1 dose. No intussusception cases occurred in the 1-21 days after dose 1 and one case occurred on day 21 after dose 2. Among the 45,367 children who received ≥1 dose of Rotavin-M1, 9.5% of children reported at least one AEFI after dose 1 and 7.3% after dose 2. Significantly higher AEFI rates occurred among children given Rotavin-M1 with pentavalent vaccines (Quinvaxem®, ComBE Five®) compared to Rotavin-M1 without pentavalent vaccines. There was no association between intussusception and Rotavin-M1. The vaccine was generally safe when administered alone and when co-administered with other vaccines.

A scoping review of active, participant centred, digital adverse events following immunization (AEFI) surveillance of WHO approved COVID-19 vaccines: A Canadian immunization Research Network study.

This scoping review examines the role of digital solutions in active, participant-centered surveillance of adverse events following initial release of COVID-19 vaccines. The goals of this paper were to examine the existing literature surrounding digital solutions and technology used for active, participant centered, AEFI surveillance of novel COVID-19 vaccines approved by WHO. This paper also aimed to identify gaps in literature surrounding digital, active, participant centered AEFI surveillance systems and to identify and describe the core components of active, participant centered, digital surveillance systems being used for post-market AEFI surveillance of WHO approved COVID-19 vaccines, with a focus on the digital solutions and technology being used, the type of AEFI detected, and the populations under surveillance. The findings highlight the need for customized surveillance systems based on local contexts and the lessons learned to improve future vaccine monitoring and pandemic preparedness.