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Adverse events following immunization with typhoid conjugate vaccine in an outbreak setting in Hyderabad, Pakistan.

ABSTRACT: Pakistan is facing the world's largest outbreak of extensively drug-resistant (XDR) Typhoid. Vaccination campaign for children aged 6 months to 10 years old with Typhoid Conjugate Vaccine (Typbar-TCV®) was conducted in high-risk areas of Hyderabad during 2018. About 207,000 children were vaccinated. Here we report the adverse events following immunization (AEFI) during the campaign. The campaign was carried out using outreach and fixed centre strategy. Community mobilizers visited each household to perform line listing and mobilize parents with age-eligible children. Children were observed for 30 min post-vaccination. Two-pronged strategy was used for ascertainment of AEFI. A 24/7 hotline number was provided to all parents/caretakers (n = 199,861) to report AEFI during 14 days following immunization. An age-stratified (n = 7139 children) were actively followed at days 7 and 14 for the ascertainment of AEFI. All AEFI were examined by three trained medical officers. A structured questionnaire using Brighton collaboration criteria with level 3 diagnostic certainty was used for the recording of AEFI. Data were analysed using Microsoft Excel Office 365. Overall, 499 AEFI (433 in the subset actively followed and 66 self-reported through hotline) were observed. The rate of AEFI was significantly higher among very young children (age group 6 to 12 months) as compared to 2 to 3 years old children (0.54% vs. 0.33% respectively; p-value < 0.001). Fever was the most common AEFI self-reported through the hotline (38/199,861 = 0.02%) and among the subset followed actively for 14 days (206/7139 = 2.89%). Fever was followed by local reactogenicity 10/199,861(0.01%), and 134/7139 (1.88%) through self-reported hotline and active follow-up, respectively. No serious AEFI was observed. Administration of a single dose of Typbar-TCV among children aged 6 months to 10 years old during an outbreak setting of Hyderabad Pakistan was safe.

SUBMITTER: Qamar FN

PROVIDER: S-EPMC7166079 | biostudies-literature | 2020 Apr

REPOSITORIES: biostudies-literature

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Adverse events following immunization with typhoid conjugate vaccine in an outbreak setting in Hyderabad, Pakistan.

Qamar Farah Naz FN Yousafzai Mohammad Tahir MT Khaliq Asif A Karim Sultan S Memon Hina H Junejo Amber A Baig Inayat I Rahman Najeeb N Bhurgry Shafqat S Afroz Hina H Sami Uzma U

Vaccine 20200320 19

Pakistan is facing the world's largest outbreak of extensively drug-resistant (XDR) Typhoid. Vaccination campaign for children aged 6 months to 10 years old with Typhoid Conjugate Vaccine (Typbar-TCV®) was conducted in high-risk areas of Hyderabad during 2018. About 207,000 children were vaccinated. Here we report the adverse events following immunization (AEFI) during the campaign. The campaign was carried out using outreach and fixed centre strategy. Community mobilizers visited each household ...[more]

PMID: 32201138

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Project description:BackgroundSalmonella enterica serotype Typhi (S Typhi) is a major public health problem in low-income and middle-income countries. We aimed to investigate the effectiveness and impact of the typhoid conjugate vaccine Typbar-TCV against S Typhi among children in an outbreak setting of extensively drug-resistant (XDR) S Typhi in Pakistan.MethodsThis cohort study was done from Feb 21, 2018, to Dec 31, 2019. A census survey of all households located in the Qasimabad and Latifabad subdistricts of Hyderabad, Pakistan, was done at baseline, and 174 005 households were registered in the census. The Typbar-TCV immunisation campaign was initiated at temporary vaccination centres and 207 000 children aged 6 months to 10 years were vaccinated from Feb 21, 2018, to Dec 31, 2018. Social mobilisers informed parents about the vaccination process. Vaccination records were maintained electronically and linked with the household census surveys. Active surveillance for suspected and blood-culture-confirmed S Typhi was established in hospitals, clinics, and laboratories to assess the following outcomes: cases of suspected typhoid fever, culture-confirmed S Typhi, and antimicrobial resistance. An age-stratified cohort of 1100 vaccinated children was randomly selected from the vaccination registry, tested for Vi-IgG antibodies (data not reported), and followed up fortnightly (via telephone calls or household visits) until Dec 31, 2019, for ascertainment of outcomes during the study period. 20 847 vaccinated and unvaccinated children were randomly selected from the census registry as a quality control cohort and followed up from Oct 1 to Dec 31, 2019, for ascertainment of outcomes. Vaccine effectiveness against suspected, culture-confirmed, and XDR S Typhi was calculated.Findings23 407 children from the census registry and surveillance system were included in the vaccine effectiveness analysis. 13 436 (57·4%) children were vaccinated, 12 214 (52·2%) were male, and 10 168 (43·4%) were aged 6-59 months. 5378 (23·0%) of 23 407 children had suspected S Typhi, among whom 775 (14·4%) had culture-confirmed S Typhi and 361 (68·6%) of 526 had XDR S Typhi. Vaccine effectiveness was 55% (95% CI 52-57) against suspected S Typhi (regardless of culture confirmation), 95% (93-96) against culture-confirmed S Typhi, and 97% (95-98) against XDR S Typhi.InterpretationTypbar-TCV is effective in protecting children against S Typhi infection in an outbreak setting, and was able, with moderate deployment, to curtail a major XDR S Typhi outbreak in a densely populated setting. The vaccine shows efficacy against S Typhi irrespective of antimicrobial resistance.FundingBill & Melinda Gates Foundation.

Project description:BackgroundSeveral prolonged typhoid fever epidemics have been reported since 2010 throughout eastern and southern Africa, including Malawi, caused by multidrug-resistant Salmonella Typhi. The World Health Organization recommends the use of typhoid conjugate vaccines (TCVs) in outbreak settings; however, current data are limited on how and when TCVs might be introduced in response to outbreaks.MethodologyWe developed a stochastic model of typhoid transmission fitted to data from Queen Elizabeth Central Hospital in Blantyre, Malawi from January 1996 to February 2015. We used the model to evaluate the cost-effectiveness of vaccination strategies over a 10-year time horizon in three scenarios: (1) when an outbreak is likely to occur; (2) when an outbreak is unlikely to occur within the next ten years; and (3) when an outbreak has already occurred and is unlikely to occur again. We considered three vaccination strategies compared to the status quo of no vaccination: (a) preventative routine vaccination at 9 months of age; (b) preventative routine vaccination plus a catch-up campaign to 15 years of age; and (c) reactive vaccination with a catch-up campaign to age 15 (for Scenario 1). We also explored variations in outbreak definitions, delays in implementation of reactive vaccination, and the timing of preventive vaccination relative to the outbreak.ResultsAssuming an outbreak occurs within 10 years, we estimated that the various vaccination strategies would prevent a median of 15-60% of disability-adjusted life-years (DALYs). Reactive vaccination was the preferred strategy for WTP values of $0-300 per DALY averted. For WTP values > $300, introduction of preventative routine TCV immunization with a catch-up campaign was the preferred strategy. Routine vaccination with a catch-up campaign was cost-effective for WTP values above $890 per DALY averted if no outbreak occurs and > $140 per DALY averted if implemented after the outbreak has already occurred.ConclusionsCountries for which the spread of antimicrobial resistance is likely to lead to outbreaks of typhoid fever should consider TCV introduction. Reactive vaccination can be a cost-effective strategy, but only if delays in vaccine deployment are minimal; otherwise, introduction of preventive routine immunization with a catch-up campaign is the preferred strategy.

Project description:BACKGROUND:Salmonella Typhi is a major cause of fever in children in low- and middle-income countries. A typhoid conjugate vaccine (TCV) that was recently prequalified by the World Health Organization was shown to be efficacious in a human challenge model, but data from efficacy trials in areas where typhoid is endemic are lacking. METHODS:In this phase 3, randomized, controlled trial in Lalitpur, Nepal, in which both the participants and observers were unaware of the trial-group assignments, we randomly assigned children who were between 9 months and 16 years of age, in a 1:1 ratio, to receive either a TCV or a capsular group A meningococcal conjugate vaccine (MenA) as a control. The primary outcome was typhoid fever confirmed by blood culture. We present the prespecified analysis of the primary and main secondary outcomes (including an immunogenicity subgroup); the 2-year trial follow-up is ongoing. RESULTS:A total of 10,005 participants received the TCV and 10,014 received the MenA vaccine. Blood culture-confirmed typhoid fever occurred in 7 participants who received TCV (79 cases per 100,000 person-years) and in 38 who received MenA vaccine (428 cases per 100,000 person-years) (vaccine efficacy, 81.6%; 95% confidence interval, 58.8 to 91.8; P<0.001). A total of 132 serious adverse events (61 in the TCV group and 71 in the MenA vaccine group) occurred in the first 6 months, and 1 event (pyrexia) was identified as being vaccine-related; the participant remained unaware of the trial-group assignment. Similar rates of adverse events were noted in the two trial groups; fever developed in 5.0% of participants in the TCV group and 5.4% in the MenA vaccine group in the first week after vaccination. In the immunogenicity subgroup, seroconversion (a Vi IgG level that at least quadrupled 28 days after vaccination) was 99% in the TCV group (677 of 683 participants) and 2% in the MenA vaccine group (8 of 380 participants). CONCLUSIONS:A single dose of TCV was immunogenic and effective in reducing S. Typhi bacteremia in children 9 months to 16 years of age. (Funded by the Bill and Melinda Gates Foundation; Current Controlled Trials number, ISRCTN43385161.).

Project description:IntroductionThe rapid rollout of coronavirus disease 2019 (COVID-19) vaccines for a large proportion of the population necessitates a strong emphasis on safety. Complementary to the existing spontaneous reporting system, The Netherlands Pharmacovigilance Centre Lareb conducted patient-reported cohort event monitoring (CEM).ObjectiveThe primary aim was to investigate differences in the frequencies of any and commonly reported, 'well-known', systemic adverse events following immunization (AEFIs) with four COVID-19 vaccines (Pfizer's Comirnaty®, Moderna's Spikevax®, AstraZeneca's Vaxzevria® and the Janssen vaccine). As a secondary aim, we analyzed the frequencies of well-known systemic adverse events after the first and, if applicable, second COVID-19 vaccinations, taking into account age, sex and prior COVID-19 infection.MethodsPatient-reported outcomes (PROs) in the Netherlands starting in February 2021 were analyzed using a prospective cohort design.ResultsData of 27,554 participants who received one vaccination and 20,682 participants who received complete immunization were analyzed. The percentage of patients reporting any AEFI was high and ranged from approximately 53% for the Pfizer vaccine to approximately 94% for the Moderna vaccine. The frequency of serious AEFIs was low, with the highest frequency found for the AstraZeneca vaccine (0.228%). AEFIs were most often experienced by participants receiving the first dose of the AstraZeneca and Janssen vaccines and the second dose of the Moderna vaccine; the Pfizer vaccine was associated with the lowest rate of AEFIs. Participants with a COVID-19 history before vaccination experienced commonly reported systemic AEFIs more frequently after the first vaccination than after the second vaccination. Women and young people experienced more AEFIs than men and older people, respectively.ConclusionsThe analysis of a large cohort provides important information about the rates of AEFIs across age groups, among brands of vaccines and between those with and without prior COVID-19 infection. Participants reported a high number of AEFIs in general, but the frequency of serious AEFIs was low.

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Adverse events following immunization with typhoid conjugate vaccine in an outbreak setting in Hyderabad, Pakistan.

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Adverse events following immunization with typhoid conjugate vaccine in an outbreak setting in Hyderabad, Pakistan.

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