Adverse events following immunization with oral poliovirus in Kinshasa, Democratic Republic of Congo: preliminary results

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.

Real-world safety profile of the 9-valent human papillomavirus vaccine: A study in Zhejiang, China from 2019 to 2021

The safety profile of the 9-valent human papillomavirus vaccine (9vHPV) was evaluated based on the reporting rate of adverse events following immunization (AEFI) obtained from the passive surveillance data in Zhejiang. The 9vHPV AEFI reports in Zhejiang were collected and reviewed from the National Adverse Event Following Immunization Surveillance System (NAEFISS) from 2019 to 2021. Reporting rates of AEFI were analyzed under multiple aspects, including age, city, number of vaccinations, AEFI categories, and diagnosis categories. This study used the reporting odds ratio (ROR) for anomalous signal assessment. The NAEFISS collected 331 AEFI reports after administering 1,064,851 doses of 9vHPV, with a crude AEFI rate of 3.12/10,000 doses. The third dose had the highest reporting rate of minor vaccine-related reaction (n = 80, 3.06 per 10,000), followed by the first dose (n = 134, 2.98 per 10,000), and second dose (n = 76, 2.15 per 10,000). Fever/redness/induration was the most common minor adverse event (281 records, 2.64/10,000 doses). Nine cases of urticaria, ten cases of allergic rash, and ten cases of syncope were recorded. This study found a positive signal association between 9vHPV immunization and adverse events such as syncope, encephalitis, sterile abscess, and urticaria. This study did not identify any new emerging safety concerns. In the future, more research is needed to validate and further explore adverse reactions associated with 9vHPV.

Using Population-Based Structures to Actively Monitor AEFIs during a Mass Immunization Campaign-A Case of Measles-Rubella and Polio Vaccines

Active vaccine pharmacovigilance complements the standard passive or spontaneous surveillance system, which suffers from low reporting rates. This study aimed at utilizing population-based structures to report and profile adverse events following immunization (AEFI) with the measles and rubella vaccine (MR), or MR in combination with the bivalent oral polio vaccine (bOPV 1&3) (MR & bOPV), during mass vaccination in Uganda. Caretakers of children at home (less than 5 years) and schoolgoing children were followed up on and encouraged to report any AEFIs on day one, 2-3 days, 10 days, and 14 days after vaccination at school by their teachers and at-home, community-based village health teams. Out of 9798 children followed up on, 382 (3.9%) reported at least one AEFI, and in total, 517 AEFIs were reported. For MR, high temperature (21%), general feeling of weakness (19.3%), and headache (13%) were the most reported AEFIs, though there were variations on the days when they were reported. For the combination dose of MR & bOPV, high temperature (44%), rash (17%), general feeling of weakness (13%), and diarrhoea (8%) were the most common adverse events following immunization reported by caretakers. All 382 children cleared the AEFIs within 2 days, with 343 (90%) children reporting mild or moderate AEFIs and only 39 (10%) reporting severe AEFIs. The reported AEFIs are known and are mentioned in the vaccine leaflets with similar severity classification. Rates of AEFIs differed with the number of days after receiving the immunization. Conclusion: Active surveillance for AEFIs provides additional important information to national vaccine regulatory bodies. It reassures the public that vaccines are safe and that their safety is being taken seriously in Uganda, which would improve vaccine acceptability and confidence in the health system. Piggybacking on existing structures such as village health team members (for children at home) and teachers (for schoolgoing children) facilitates reaching vaccine recipients and increases reporting rates. Therefore, studies using active reporting of AEFIs should be conducted at regular intervals to report the overall incidence of AEs and to monitor trends and changes.

Analysis of adverse events following immunization in Zhejiang, China, 2019: a retrospective cross-sectional study based on the passive surveillance system

Objectives: This study summarizes passive surveillance data for adverse events following immunization (AEFI) in Zhejiang province.Methods: The AEFI reports and number of doses on all vaccines used were extracted from the national AEFI surveillance system and the immunization information system of Zhejiang province (ZJIIS). Reporting rates of AEFI were calculated by age, city, severity of AEFI, categories of AEFI, vaccine types, and reaction categories.Results: A total of 13,079 AEFI records were reported and 23,091,401 vaccine doses were administered, with a reporting rate of 56.64/100,000 doses for AEFI. The highest reporting rate of AEFI was observed among the infants <1 year of age (108.61/100,000 doses) and the lowest rate was observed among recipients aged ≥60 years. Most of the AEFI reports were vaccine product-related reactions (48.81/100,000 doses), and the lowest was vaccination errors (0.02/100,000 doses). The most frequently reported individual vaccine was DTP and Hib combined vaccine, with a reporting rate of 426.62/100,000 doses. The most frequently reported AEFI was fever/redness/induration (48.82/100,000 doses).Conclusion: Our findings illustrated the high level of vaccine safety since the majority of those reported were not serious, or coincidentally associated with vaccination. Furthermore, the national AEFI surveillance system should be continuously used as a surveillance tool for monitoring of AEFI.

Adverse events following immunization with bivalent oral poliovirus vaccine in Jiangsu, China

AIMS

The bivalent oral poliovirus vaccine (bOPV; Sabin types 1 and 3) replaced the trivalent OPV (Sabin types 1, 2 and 3) globally in April 2016. A routine schedule of 1 dose of inactivated poliovirus vaccine and 3 subsequent doses of bOPV was implemented in Jiangsu simultaneously. The schedule was changed to 2 inactivated poliovirus vaccines + 2 bOPV on 1 September 2019. Although OPV type 2 has been removed, challenges persist because of adverse events following immunization (AEFIs) with bOPV. Therefore, we analysed and evaluated the safety profile of bOPV administered in children based on passive postmarketing AEFI surveillance.

METHODS

We collected all bOPV-related AEFI reports in Jiangsu from the Chinese National AEFI Information System (CNAEFIS) between May 2016 and April 2020. We obtained the administered doses of bOPV from the Jiangsu Provincial Electronic Immunization Registries System. A descriptive analysis was performed.

RESULTS

In total, 2084 bOPV-related AEFIs were retrieved from the CNAEFIS. The overall reporting rate was 24.16 per 100 000 doses. Most AEFIs were nonserious. The most frequently reported symptoms were fever, rash and gastrointestinal disorders. Only 1.34% of AEFIs were serious, which thrombocytopenic purpura accounted for the largest category. Seventeen serious adverse events, including 2 vaccine-associated paralytic poliomyelitis (VAPP) cases, were considered to be related to bOPV vaccination. The rate of VAPP was 0.2 per million doses.

CONCLUSION

AEFI analysis showed that bOPV was well tolerated. The events most frequently reported were nonserious. However, bOPV can still cause VAPP. Attention should be given to risks related to bOPV.

Enterovirus infections in pediatric patients hospitalized with acute gastroenteritis in Chiang Mai, Thailand, 2015-2018

Background

Infection with viruses especially rotavirus, norovirus, astrovirus, and adenovirus has been known to be a major cause of acute gastroenteritis in children under 5 years of age globally, particularly in developing countries. Also, some genotypes of enteroviruses (EVs) have been reported to be associated with gastroenteritis. This study is aimed to investigate the prevalence and genotype diversity of EV in children admitted to hospitals with acute gastroenteritis.

Methods

A total of 1,736 fecal specimens were collected from children hospitalized with diarrhea in Chiang Mai, Thailand from 2015 to 2018. All specimens were tested for the presence of EV by RT-PCR of the 5' untranslated region. The genotypes of EV were further identified by nucleotide sequencing and phylogenetic analysis of the viral protein 1 (VP1) gene.

Results

EV was detected in 154 out of 1,736 specimens (8.9%) throughout the study period. The prevalence of EV detected in 2015, 2016, 2017, and 2018 was 7.2%, 9.0%, 11.2%, and 8.6%, respectively. EV was detected all year round with a high prevalence during rainy season in Thailand. Overall, 37 genotypes of EV were identified in this study. Among these, coxsackievirus (CV)-A24 and CV-B5 (7.5% each), and EV-C96 (6.8%) were the common genotypes detected.

Conclusion

This study demonstrates the prevalence, seasonal distribution, and genotype diversity of EV circulating in children hospitalized with acute gastroenteritis in Chiang Mai, Thailand during the period 2015 to 2018.

Enteroviruses in gastrointestinal diseases

Gastrointestinal diseases including diarrhoea constitute a major cause of morbidity and mortality in infants and young children especially in developing countries. Worldwide deaths among all ages due to diarrhoea during 2015 were estimated to be about 1.31 million, diarrhoeal deaths in children below 5 years of age being 499 000. Rotavirus accounted for about 200 000 deaths. Although diarrhoeal deaths decreased significantly during the last two decades, they still represent the third largest cause of infantile deaths. Several bacterial, viral, parasitic, fungal and non-infectious diarrhoea causing agents have been identified, but 30% to 40% of diarrhoeal cases remain undiagnosed. Enteroviruses transmit by the faecal-oral route and replicate first in intestinal cells before spreading to the target organ. They have been associated with diarrhoea in a few studies, but their causative role in diarrhoea in humans has not been systematically demonstrated. In view of the recent demonstration that enteroviruses cause diarrhoea in newborn mice pups, thus validating Koch's postulates, the purpose of this review is to emphasise the importance of recognising enteroviruses as major gastrointestinal pathogens associated with acute and persistent diarrhoea and non-diarrhoeal increased frequency of bowel movements in infants, young children and adults. Our studies and several other subsequent studies reported from different countries should stimulate strategies to reduce the burden of infantile gastrointestinal disease, which has hitherto remained unaddressed.

Safety profile of the meningococcal conjugate vaccine (Menafrivac™) in clinical trials and vaccination campaigns: a review of published studies

The study aimed to assess the capacity of AEFI surveillance during vaccination campaigns with the new conjugate meningitis vaccine (MenAfrivac). A systematic review of studies on MenAfrivac™ published in English during 2001-2016 was done.AEFIs incidence (I) was estimated and compared between MenAfrivac™ clinical trials and immunization campaigns using incidence difference (Id). Nine studies were included with an overall local AEFI I of 11,496/100,000 doses administered per week in clinical trials and 0.72/100,000 doses in immunization campaigns. An Id of 11,497.92 [11,497.91-11,497.93] and 17,243.20 [17,241.80-17,245.90] per 100,000 doses administered per week for overall local and systemic AEFI, respectively, were observed with highest from clinical trials. The incidence of AEFIs after MenAfrivac™ vaccination was far lower in campaigns than in clinical trial studies. Current capacity of AEFI surveillance during vaccination campaigns requires extensive re-assessment of its structure and capacity.

Analysis of health outcomes in vaccinated and unvaccinated children: Developmental delays, asthma, ear infections and gastrointestinal disorders

OBJECTIVE

The aim of this study was to compare the health of vaccinated versus unvaccinated pediatric populations.

METHODS

Using data from three medical practices in the United States with children born between November 2005 and June 2015, vaccinated children were compared to unvaccinated children during the first year of life for later incidence of developmental delays, asthma, ear infections and gastrointestinal disorders. All diagnoses utilized International Classification of Diseases-9 and International Classification of Diseases-10 codes through medical chart review. Subjects were a minimum of 3 years of age, stratified based on medical practice, year of birth and gender and compared using a logistic regression model.

RESULTS

Vaccination before 1 year of age was associated with increased odds of developmental delays (OR = 2.18, 95% CI 1.47-3.24), asthma (OR = 4.49, 95% CI 2.04-9.88) and ear infections (OR = 2.13, 95% CI 1.63-2.78). In a quartile analysis, subjects were grouped by number of vaccine doses received in the first year of life. Higher odds ratios were observed in Quartiles 3 and 4 (where more vaccine doses were received) for all four health conditions considered, as compared to Quartile 1. In a temporal analysis, developmental delays showed a linear increase as the age cut-offs increased from 6 to 12 to 18 to 24 months of age (ORs = 1.95, 2.18, 2.92 and 3.51, respectively). Slightly higher ORs were also observed for all four health conditions when time permitted for a diagnosis was extended from ⩾ 3 years of age to ⩾ 5 years of age.

CONCLUSION

In this study, which only allowed for the calculation of unadjusted observational associations, higher ORs were observed within the vaccinated versus unvaccinated group for developmental delays, asthma and ear infections. Further study is necessary to understand the full spectrum of health effects associated with childhood vaccination.

A review of the safety of vaccines used in routine immunization in Africa

BACKGROUND

Despite the significant role played by vaccines in global health, concerns over vaccine safety have increased tremendously over the years. There have been occasions where vaccines have caused rare, adverse reactions some of which have led to hospitalizations and even death. It is therefore important to establish the safety profile of routinely used vaccines in order to allay fears pertaining to their use.

OBJECTIVES

This review was aimed at pooling together the safety data of selected vaccines used for routine immunization in Africa, a region of the world with paucity of vaccine safety data.

METHODS

Adverse Events Following Immunization safety data was searched for rotavirus, yellow fever, measles, rubella, tuberculosis (Bacillus Calmette Guerin-BCG), pneumococcal, Haemophilus Influenza type b, polio, meningococcal and the influenza A (H1N1) vaccines in PUBMED, Google Scholar, Clinical trials.gov and Cochrane controlled register of trials databases.

RESULTS

A total of twenty-four serious AEFIs and twenty-three minor AEFIs were identified from the review. The strength of association between AEFIs and vaccine was high for tuberculosis vaccine and moderate for all other vaccines.

CONCLUSION

Even though AEFIs (including mild and severe) were identified in the review, all the vaccines studied were generally well tolerated.

Development of a pharmacovigilance system in a resource-limited country: the experience of the Democratic Republic of Congo

Implementation of pharmacovigilance (PV) systems in resource-limited countries is a real endeavor. Despite country- and continent-specific challenges, the Democratic Republic of the Congo (DRC) has been able to develop one of the most active PV systems in the sub-Saharan Africa. The World Health Organization (WHO) regional Office identified the DRC experience to set up a PV system for antimalarial drugs safety monitoring as a ‘best practice’ that needed to be documented in order to help DRC improve its PV system and to be scaled up in other African countries. In response to the WHO request, a best practices and bottlenecks analysis was conducted in 2015. This analysis was updated in 2018 in the light of the minimum requirements of the WHO to set up a PV system taking into account other guidance for PV systems. The following themes were retained for analysis: (1) creation of the national PV center; (2) implementation of PV in the health system; (3) data collection and analysis; (4) collaboration with public health programs; (5) collaboration with the National Regulatory Authority. Lessons learnt from the DRC experience show that it is possible to implement PV systems in order to promote patients’ safety in resource limited sub-Saharan African countries with no guaranteed funding. The ability of national PV centers to collaborate with Public health stakeholders, including public health authorities at all levels as well as public health programs, and to use existing health information systems are considered the main key to success and may substantially reduce the cost of PV activities.

Safety profile of fractional dosing of the 17DD Yellow Fever Vaccine among males and females: Experience of a community-based pharmacovigilance in Kinshasa, DR Congo

BACKGROUND

In early 2016, there was a Yellow Fever (YF) outbreak in Central Africa with several deaths reported from Angola and the Democratic Republic of Congo. Due to a shortage in vaccine supply, fractional dosing (0.1 ml) of 17DD Yellow Fever Vaccine (YFV) was proposed in preventive vaccination campaign in Kinshasa in August 2016. A Pharmacovigilance surveillance at community level was implemented to track Adverse Events Following Immunization (AEFIs). The objective of this study was to describe AEFIs as captured from community-based pharmacovigilance and to compare the safety profile of the fractional dosing of YFV between gender.

METHODS

PV information sessions were organized in churches, academic institutions, and pediatrician, obstetrician and friend networks. Prior to data collection, education about AEFI was provided through face-to-face discussions, phone calls, SMS and WhatsApp messages. Individuals reported AEFIs though the above communication channels to assigned individuals. Reported AEFIs were entered into VigiFlow and extracted for statistical analysis using Stata 12. Only vaccinees who received fractional dose (subjects from the age of 2-year-old and non-pregnant women) were included in analysis. Proportional t-test was used to compare AEFI preferred terms among males and females.

RESULTS

A total of 4020 subjects reported 5409 AEFIs. Reporters were mostly males (54.9%) with an average age of 26 ± 10.7 years. Fever and injection site pain were the most reported systemic and local AEFI respectively. The safety profile was similar between gender although females reported more diarrhea and dizziness whilst males reported more asthenia (P < 0.001). Five individuals reported serious AEFIs. Among them, 4 were less-immunocompetent.

CONCLUSION

Fractional dosing of 17DD YFV has a good safety profile, which is similar between gender. These findings complement the documented immunogenicity profile to support recommendation of fractional dose of YFV for outbreak control.

Assessment of attitudes towards adverse events following immunization with oral poliovirus vaccine: a pilot study among high school students of Kinshasa, the Democratic Republic of Congo

OBJECTIVE

The aim of this study is to evaluate the reaction of students to adverse events following immunization in order to offer a baseline for developing a communication and risk management plan.

METHOD

This is a cross-sectional study conducted in Kinshasa. A survey was conducted between the third and the fourth rounds of Supplementary Immunization Activity. Nine hundred and fifty questionnaires were used and addressed students who attended this university from 1 to 10 June 2011.

RESULTS

Completed questionnaires were received from 848 students, with 485 females (57·2%), 343 males (40·4%), and 20 unknown (2·4%); 46·9% of students were from the faculty of medicine and 24·7% was from the third graduate degree. From those who completed the questionnaire, 136 (16·4%) reported experiencing an adverse events following immunization. Concerning the attitude of students towards adverse events following immunization, 79 students (58·5%) did nothing; 54 (40·0%) opted for self-medication; 2 (1·5%) went to the hospital.

CONCLUSION

The main finding of our study is the low rate of people referring to health-care providers for vaccine-related problems, more specially for adverse events following immunization. A risk management plan should be focused in strategies to increase communication between population and health-care providers.