Background: Vaccine hesitancy has become a prominent public health concern, particularly within the coronavirus disease 2019 (COVID-19) pandemic context. Worries about vaccine side effects are often cited as a reason for hesitancy, while media reporting about this topic plays an important role in influencing the public\'s perspectives about vaccines and vaccination. In Vietnam, during 2012-2013, there were several adverse events following immunization (AEFIs) of Quinvaxem- a pentavalent vaccine in the Expanded Immunization Program, which made big headlines in the media. Such incidences have contributed to changes in vaccination policies and influenced parents\' concerns to date. This study explores the portrayal of Quinvaxem in Vietnam digital news during four periods marked by important events. Methods: We performed quantitative and qualitative analysis with a coding framework to identify main content focus, sentiments towards Quinvaxem, and emotional tones in these articles. Results: In total, we included 360 articles into analysis. The amount of news coverage about Quinvaxem increased after AEFIs happened, from 7 articles before AEFIs to 98 and 159 articles in the following periods when AEFIs and investigation into vaccine safety occurred. Most articles are neutral in titles (n=255/360) and content (n=215/360) towards Quinvaxem and do not convey emotional expressions (n=271/360). However, articles focusing on side effects contain negative sentiments and emotional expressions more frequently than articles of other contents while AEFIs details were conflicting across articles. Vaccine sentiments are provoked in the information about vaccine quality and safety, health authority, local delivery, and quoted vaccine opinions. Emotion-conveying elements in 89/360 articles included emotional wording and imagery and expressive punctuation. Conclusions: The heterogeneity of information in online news may reinforce uncertainty about vaccine safety and decrease vaccine intention. Our results have important implications for vaccine communication, given the current plan of the Vietnamese government to roll out COVID-19 vaccination to younger children.

UNASSIGNED: The Haemophilus influenzae type b (Hib) conjugate vaccine is widely administered in China.
UNASSIGNED: 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.
UNASSIGNED: 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.
UNASSIGNED: 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.

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.

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.

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.
METHODS: 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.

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.

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.

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.

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.

UNASSIGNED: 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.
UNASSIGNED: 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.
UNASSIGNED: 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.
UNASSIGNED: 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.