Adverse Menstrual Events Reported After and Before (or Without) COVID-19 Vaccination: A Systematic Review and Meta-Analysis of Comparative Observational Studies.

BACKGROUND: Reports of adverse menstrual events emerged during the COVID-19 vaccination campaign in multiple countries. This raised the question whether these reports were caused by the vaccines. The aim of this systematic review was to evaluate comparative studies on this topic (registered at PROSPERO [CRD42022324973]). METHODS: We included observational studies such as cohort studies and surveys comparing the response to self-reported questionnaires between post- versus pre-vaccination data. PubMed and Cochrane Library searches were conducted on 1 September 2023. The primary outcome was the incidence of any prespecified adverse menstrual event, and the outcome measure was the risk ratio. The meta-analysis was conducted by using the Mantel-Haenszel method and the random effects model. We summarized the results on risk factors as well as key findings of the studies included. RESULTS: We retrieved 161 references from electronic databases and additional sources such as references lists. Of those, we considered 21 comparative observational studies. The meta-analysis of any adverse menstrual adverse event reported in 12 studies resulted in a pooled estimate (risk ratio 1.13; 95% CI, 0.96-1.31) that did not favor any group. The analysis was constrained by considerable clinical and statistical heterogeneity. Risk factors for self-reported menstrual changes included a history of COVID-19 infection, the concern about COVID-19 vaccines, smoking, previous cycle irregularities, depression, and stress, and other issues. CONCLUSIONS: The risk ratio did not favor any group and heterogeneity was prevalent among the studies. Most studies suggested that the reported changes were temporary, minor, and nonserious.

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.

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.

Post-Marketing Surveillance of Adverse Events Following Immunization with Haemophilus Influenzae Type b Conjugate Vaccine - China, 2010-2021.

Introduction: The Haemophilus influenzae type b (Hib) conjugate vaccine is widely administered in China. Methods: We extracted data on Hib vaccine doses administered and adverse events following immunization (AEFI) reported between 2010 and 2021 from the Chinese National Immunization Information System (CNIIS). A descriptive analysis was conducted to examine the characteristics and incidence rates of AEFI with the Hib vaccine. Results: In China, between 2010 and 2021, a total of 52,910 AEFIs with the Hib vaccine were reported, resulting in an overall AEFI reporting rate of 38.10 per 100,000 doses. Common (typically minor) and rare (potentially serious) vaccine reactions occurred at rates of 34.71 and 2.78 per 100,000 doses, respectively. Among the common vaccine reactions, the incidences of fever (axillary temperature ≥38.6 ℃), injection site redness and swelling (>2.5 cm in diameter), and injection site induration (>2.5 cm in diameter) were 11.93, 9.69, and 3.38 per 100,000 doses, respectively. Rare vaccine reactions included anaphylactic rash, angioedema, and febrile convulsion with reported incidences of 2.42, 0.10, and 0.05 per 100,000 doses, respectively. The incidence of serious rare vaccine reactions was 0.16 per 100,000 doses. Conclusions: The reported incidence of AEFI with the Hib vaccine was low, with the occurrence of serious rare adverse reactions also being markedly low throughout the period 2010-2021 in China.

Short- and long-term outcomes of cardiac adverse events following COVID-19 immunization managed in a Canadian pediatric center.

BACKGROUND: Numerous reports have described the clinical presentation of cardiac adverse events following immunization (AEFI) with COVID-19 vaccines but long-term outcome studies are limited, especially in the pediatric population. METHODS: This is a single center retrospective case series of pediatric patients with cardiac AEFI following the Pfizer/BioNTech mRNA COVID-19, diagnosed between May 2021 and May 2022, and managed following a standardized protocol. Follow up information is presented up to 12 months post diagnosis. The incidence rate of cardiac AEFI was estimated for Ottawa residents. RESULTS: All cases were male (N = 17) with an average age of 16 years (range = 12-17). The majority of cases occurred after the 2nd (12/17) or 3rd vaccine dose (4/17) and were manifested mostly as myopericarditis (15/17). Average interval between the 1st and 2nd vaccine (n = 12) doses was 38 days (21-69 days). All patients improved promptly on non-steroidal anti-inflammatory drugs without recurrence. Five patients reported negative impact on quality of life and mental health, including 2 cases that led to new vaccine hesitancy, not only to COVID-19 vaccine, but also to other routine vaccines. The rate of cardiac AEFI was estimated for residents of the city of Ottawa and found to be 12.01 cases (CI 90 5.98-21.68) per 100,000 doses following the 2nd dose and 16.56 cases (CI 90 5.66-37.90) per 100,000 doses following the 3rd dose for males aged 12 to 17 years. CONCLUSIONS: Twelve months following the AEFI, all patients clinically recovered from their myopericarditis, but some reported negative impact on quality of life and mental health, including new vaccine hesitancy. This highlights the importance for timely and systematic evaluation of AEFI and the need to provide support, follow up and vaccine counseling in individuals experiencing an AEFI.

Comparison of Transient and Persistent Adverse Events After COVID-19 Vaccination: A Retrospective Analysis.

OBJECTIVE: Most reported adverse events following COVID-19 vaccination have been transient. However, persistent adverse events may occur with some frequency. This study aimed to analyze patient background characteristics and trends, with a focus on whether adverse events following COVID-19 vaccination were transient or persistent. METHODS: A retrospective study was performed at a single institution in Japan. PATIENTS: The study cohort included 47 patients who presented with symptoms after COVID-19 vaccination between May 2021 and September 2023. The patients were classified into two groups based on the duration of symptoms: transient group, less than four weeks; persistent group, greater than or equal to four weeks. Data on age, sex, body mass index, smoking history, underlying conditions, type of COVID-19 vaccination, number of doses, onset, symptoms, and treatments were collected retrospectively. RESULTS: The median age was 51.0 years and 74.5% were females, with a particularly high proportion of women in their 40s. The use of the bivalent omicron-containing booster vaccine (BA.1) was significantly more common in the persistent group than in the transient group (p = 0.0267). Onset in the transient group was more common after the first vaccination, whereas onset in the persistent group was more common after the second and subsequent vaccinations (p = 0.003). Regarding symptoms, pain was more frequent in the persistent group than in the transient group (60% vs. 13.6%; p = 0.001). CONCLUSIONS: This study investigated the presence of persistent symptoms, especially pain, after COVID-19 vaccination. Persistent symptoms were frequently reported after the second vaccination. It should be noted that the study does not negate the usefulness of COVID-19 vaccines.

Pharmacovigilance in Vaccines: Importance, Main Aspects, Perspectives, and Challenges-A Narrative Review.

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.

Analysis of Adverse Events Post-13-Valent Pneumococcal Vaccination among Children in Hangzhou, China.

With the widespread use of the 13-valent pneumonia vaccine (PCV13) in China, monitoring adverse events following immunization (AEFIs) is critical. We conducted a descriptive analysis of the AEFI occurrences reported within Hangzhou between the years 2020 and 2023, including the temporal trend of case reports and variables such as sex, age, type of PCV13, dose number, type of reporter, cause-specific classification, severity, and onset from vaccination. Vaccine safety signals were analyzed using reporting odds ratios (RORs). Over the 4 years analyzed in the study, 2564 AEFI cases were reported, including seven severe cases. Most AEFIs occurred within 0-1 days after vaccination (2398, 93.53%), with over half affecting infants aged 1.5-6 months of age. No statistically significant difference was observed between PCV13-TT and PCV-CRM197. Seasonal differences in AEFI reports were noted. Positive signals were detected for fever (ROR-1.96SE: 1.64) and persistent crying (ROR-1.96SE: 1.61). Four serious AEFI cases were coincidental events, while three others were considered vaccine-related cases (including one case each of allergic reaction, febrile seizure, and thrombocytopenia). The safety and tolerability of PCV13 are good, and attention should be paid to severe AEFIs, as well as long-term safety disparities between different types of PCV13.

mRNA COVID-19 vaccine safety among older adults from the Canadian National Vaccine Safety Network.

This study examined short-to-medium term safety of COVID-19 vaccines among adults aged ≥65 years using the Canadian National Vaccine Safety Network active safety surveillance data. Both vaccinated and unvaccinated older adult participants recruited from seven provinces and territories were included in the analysis. Safety was assessed at 7 days after COVID-19 vaccination (dose 1, 2 and 3), and 7 months after dose 1. Multivariable logistic regression was used to examine the association between BNT162b2/mRNA-1273 COVID-19 vaccines and two short-term health events: 1) health event preventing daily activities and/or required medical consultation, 2) serious health events resulting in an emergency department visit and/or hospitalization within 7 days following each dose. We also assessed the rates of serious health events for the period between dose 1 and 2, and 7-months following dose 1. Between December 2020 and February 2022, a total of 173,038, 104,452, and 13,970 older adults completed dose 1, dose 2, and dose 3 surveys, respectively. The control survey was completed by 2,955 unvaccinated older adults. Health events occurred more frequently among recipients after dose 2 homologous mRNA-1273 (adjusted odds ratio [95 % confidence interval]: 2.91 [2.24-3.79]) and dose two heterologous (BNT162b2 followed by mRNA-1273): 1.50 [1.12-2.02] compared to unvaccinated counterparts. There was no difference in event rates after any dose of BNT162b2 and unvaccinated participants. The rates of serious health events following COVID-19 vaccination were very low (≤0.3 %) across all vaccine products and doses, and were not higher compared to unvaccinated controls, and were not associated with an emergency department visit or hospitalization within 7 days following vaccination. Reported symptoms were self-limited and rarely required medical assessment. Our findings further strengthen the current evidence that mRNA COVID-19 vaccines are safe and can be used to inform older adults about expected adverse events following COVID-19 vaccination.

Thrombosis With Thrombocytopenia and Post-COVID-Vaccination Syndrome With Anti-G-Protein-Coupled Receptor (GPCR) Antibodies Treated With Therapeutic Plasma Exchange.

We present the case of a female who developed cerebral venous thrombosis with thrombocytopenia after inoculation with the anti-coronavirus disease 2019 (COVID-19) Vaxzevria vaccine, followed by splanchnic thrombosis and diffuse hemorrhages. Despite receiving treatment, the complications increased, and hence therapeutic plasma exchange (TPE) was attempted, leading to laboratory and clinical improvements and discharge after a period of intensive care. Almost two years after the first episode, in the interim of which the patient complained of only minor symptoms such as asthenia and difficulty concentrating, she developed an epileptic syndrome that required neurological treatment. In addition, her fatigue and difficulty concentrating worsened and other serious symptoms of dysautonomia appeared, such as trembling of her right arm, loss of stability, and postural orthostatic tachycardia. As serum analysis revealed a significant number of alterations in autoantibodies against various G-protein-coupled receptors (GPCRs) and RAS-related proteins, two further TPEs were performed, resulting in rapid and sustained clinical improvement. This report highlights the role of the different types of autoantibodies produced in response to anti-COVID-19 vaccination, which can have functional, regulatory, and possibly pathogenic effects on the vascular and nervous systems.

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.

Safety profile of recombinant adjuvanted anti-herpes zoster vaccine (RZV) in high-risk groups: Data from active surveillance program. Puglia (Italy), 2021-23.

BACKGROUND: Since 2021 a recombinant adjuvanted anti-Herpes Zoster vaccine(Recombinant Zoster Vaccine, RZV) is offered in Italy to high-risk patients. Few real-life data about RZV safety are available in target populations. OBJECTIVES: This study investigates Adverse Events Following Immunization(AEFIs), baseline disease flare-ups, and Herpes Zoster (HZ) episodes occurring after RZV administration in a heterogeneous population of fragile patients to design its safety profile. METHODS: This is a retrospective population-based study. RZV-vaccinated patients at Bari Policlinico General Hospital vaccination clinic from October 1st, 2021, to March 31st, 2023, were enrolled. Subjects were screened for reason of RZV eligibility and baseline chronic pathologies. AEFIs occurred in the first 7-days post-vaccination period were collected, and baseline disease flare-ups and post-vaccination HZ episodes were assessed via a 3-month follow-up. RESULTS: Five-hundred-thirty-eight patients were included and total of 1,031 doses were administered. Most patients were vaccinated due to ongoing immunosuppressive therapy(54.65 %); onco-hematological and cardiovascular conditions were the most common chronic baseline pathologies. Out of 1,031 follow-ups, 441 AEFI cases were reported(42.7/100). The most common symptoms were injection site pain/itching(35.60/100), asthenia/malaise(11.44/100), and fever (10.09/100). Four serious AEFIs occurred(0.38/100). Older age, male sex, and history of cardiovascular diseases(OR:0.71; 95CI:0.52-0.98; p-value <0.05) were found to decrease AEFIs risk, while endocrine-metabolic illnesses(OR:1.61; 95CI:1.15-2.26; p-value <0.05) increased it. Twelve patients(2.23 %) reported a flare-up/worsening of their baseline chronic condition within the first three months after vaccination(mean interval 31.75 days, range 0-68 days). Patients with rheumatological illnesses had a higher risk of relapse(OR:16.56; 95CI:3.58-76.56; p-value <0.001), while male sex behaved as a protective factor. Twelve patients who completed the vaccination cycle(2.43%) had at least one HZ episode by the long-term follow-up. CONCLUSIONS: The study demonstrates RZV safety in a significant number of high-risk patients. Hence, RZV should be actively offered as part of tailored vaccination programs to decrease the burden of HZ in fragile populations.

National safety monitoring of vaccines from the Canadian Adverse Events Following Immunization Surveillance System (CAEFISS), 2018-2019.

Background: The Canadian Adverse Events Following Immunization Surveillance System (CAEFISS) is a comprehensive vaccine safety surveillance system that includes both passive and active surveillance of vaccines administered in Canada. This work presents a summary of adverse events following immunization (AEFI) nationally for 2018 and 2019. Methods: Data extracted from CAEFISS included all AEFI reports received by the Public Health Agency of Canada by April 30, 2022, for vaccines marketed in Canada and administered between January 1, 2018, and December 31, 2019. Descriptive statistics were conducted on AEFI reports by type of surveillance program (i.e., active vs. passive), AEFIs, demographics, healthcare utilization, outcome, seriousness of adverse events and type of vaccine. Results: Between 2018 and 2019, 5,875 AEFI reports were received from across Canada. The average annual AEFI reporting rate was 10.9/100,000 doses distributed in Canada for vaccines administered during 2018-2019 and was found to be inversely proportional to age. The majority of reports (91%) were non-serious events, involving vaccination site reactions, rash and allergic events. Overall, there were 511 serious adverse event reports during 2018-2019. Of the serious adverse event reports, the most common primary AEFIs were anaphylaxis followed by seizure. There were no unexpected vaccine safety issues identified or increases in frequency or severity of adverse events. Conclusion: Canada's continuous monitoring of the safety of marketed vaccines during 2018-2019 did not identify any increase in the frequency or severity of AEFIs, previously unknown AEFIs, or areas that required further investigation or research.

Adverse events following immunization of ChAdOx1 nCoV-19 vaccine among healthcare workers of a medicine-teaching institution of North India.

Objective: This study sought to assess the prevalence of adverse events following immunization (AEFI) and factors associated with AEFI of the ChAdOx1 nCoV-19 vaccine (Covishield) among healthcare workers (HCW) of a medicine-teaching institution of North India. Materials and Methods: A cross-sectional study was conducted in the months of June and July 2021 among HCW (N = 203) of 18 years and above, vaccinated with at least the first dose of Covishield. A semi-structured, prevalidated, and pretested questionnaire was used to collect information through an interview schedule. The questionnaire was divided into five sections: the sociodemographic profile, behavioral characteristics, past medical history, COVID-19 awareness, and past infection and COVID-19 vaccine related information. Chi-squared test was applied to check the association of different factors with AEFI. Results: In our study, 73.89% of participants suffered from at least one AEFI after the first dose of the vaccine, while 48.66% had at least one AEFI after the second dose. Females reported significantly high AEFI for both doses (P = 0.001, 0.000). We found a significant association between the occurrence of AEFI and occupation (first dose P = 0.015), substance abuse (first dose P = 0.002), diet (first dose P = 0.016), and allergy (first dose P = 0.027). Other significant findings were headaches among HCW ≥40 years of age (dose P = 0.034) and systemic AEFI in participants with comorbidity (first dose P = 0.020). Conclusion: More AEFI were reported after the first dose as compared to the second dose. AEFI were more among females after both the doses. Occupation, substance use, diet, and history of allergy were significantly associated with AEFI.

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.

COVID-19 vaccines and adverse events of special interest: A multinational Global Vaccine Data Network (GVDN) cohort study of 99 million vaccinated individuals.

BACKGROUND: The Global COVID Vaccine Safety (GCoVS) Project, established in 2021 under the multinational Global Vaccine Data Network™ (GVDN®), facilitates comprehensive assessment of vaccine safety. This study aimed to evaluate the risk of adverse events of special interest (AESI) following COVID-19 vaccination from 10 sites across eight countries. METHODS: Using a common protocol, this observational cohort study compared observed with expected rates of 13 selected AESI across neurological, haematological, and cardiac outcomes. Expected rates were obtained by participating sites using pre-COVID-19 vaccination healthcare data stratified by age and sex. Observed rates were reported from the same healthcare datasets since COVID-19 vaccination program rollout. AESI occurring up to 42 days following vaccination with mRNA (BNT162b2 and mRNA-1273) and adenovirus-vector (ChAdOx1) vaccines were included in the primary analysis. Risks were assessed using observed versus expected (OE) ratios with 95 % confidence intervals. Prioritised potential safety signals were those with lower bound of the 95 % confidence interval (LBCI) greater than 1.5. RESULTS: Participants included 99,068,901 vaccinated individuals. In total, 183,559,462 doses of BNT162b2, 36,178,442 doses of mRNA-1273, and 23,093,399 doses of ChAdOx1 were administered across participating sites in the study period. Risk periods following homologous vaccination schedules contributed 23,168,335 person-years of follow-up. OE ratios with LBCI > 1.5 were observed for Guillain-Barré syndrome (2.49, 95 % CI: 2.15, 2.87) and cerebral venous sinus thrombosis (3.23, 95 % CI: 2.51, 4.09) following the first dose of ChAdOx1 vaccine. Acute disseminated encephalomyelitis showed an OE ratio of 3.78 (95 % CI: 1.52, 7.78) following the first dose of mRNA-1273 vaccine. The OE ratios for myocarditis and pericarditis following BNT162b2, mRNA-1273, and ChAdOx1 were significantly increased with LBCIs > 1.5. CONCLUSION: This multi-country analysis confirmed pre-established safety signals for myocarditis, pericarditis, Guillain-Barré syndrome, and cerebral venous sinus thrombosis. Other potential safety signals that require further investigation were identified.

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.

Safety study of 23-valent pneumococcal polysaccharide vaccine in Hebei Province / 公共卫生与预防医学

Objective To analyze the occurrence characteristics of adverse events following immunization (AEFI) of 23-valent pneumococcal polysaccharide vaccine (PPSV-23) in Hebei Province and to evaluate the safety of the vaccine. Methods AEFI cases related to vaccination of PPSV-23 in Hebei Province from January 1, 2020 to December 31, 2022 were collected through the AEFI surveillance module of Chinese Center for Disease Control and Prevention Information System. The incidence of reported AEFI cases were then analyzed and compared. Results The reported incidence rate of AEFI of PPSV-23 was 56.12 /100,000 doses, and the incidence rate of adverse reactions was 55.50 /100 000 doses. The incidence rate of common adverse reactions was 53.94/100 000 doses, and the incidence rate of rare adverse reactions was 1.56/100 000 doses. Most of the reported AEFI cases caused by PPSV-23 were common adverse reactions, which occurred mainly within one day after vaccination, and the overall regression was positive. Conclusion The 23-valent pneumococcal polysaccharide vaccine used in Hebei Province is safe，but its safety monitoring still needs to be strengthened.

Analysis of death cases in Shenyang City, China, for immunization adverse event surveillance, 2009-2021.

Through the Chinese National Immunization Adverse Event Surveillance System (CNAEFIS), we collected reports of Adverse Event Following Immunization (AEFI) deaths in Shenyang from 2009 to 2021 with the aim of analyzing AEFI-related deaths and assessing the safety of vaccination. From 2009 to 2021, a total of 12 AEFI-related deaths were reported in Shenyang City, and autopsies were performed in 6 deaths. According to the assessment of the Expert Committee on Investigation and Diagnosis of AEFI 3 (25.0%) deaths were classified as severe vaccine reactions, 9 (75.0%) deaths were classified as coincidental events, and there were no immunization errors or psychological reactions. The overall estimated AEFI-related mortality rate was 0.12 per 100,000 vaccination doses. Spearman's rank correlation analysis showed no correlation between AEFI, severe vaccine reactions, and suspected vaccination-related deaths. Coincidental events are the most common type of death following vaccination, meaning that the risk of death following immunization is low, and ongoing AEFI surveillance and scientific causality assessment are essential to ensure the vaccine confidence. Detailed pre-vaccination health status questioning is also key to avoiding and reducing adverse events.