Case Fatality Rate of Enteric Fever in Endemic Countries: A Systematic Review and Meta-analysis

Pieters, Zoë; Saad, Neil J.; Antillón, Marina; Pitzer, Virginia E.; Bilcke, Joke

doi:10.1093/cid/ciy190

Cited by 33 publications

(26 citation statements)

References 48 publications

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“…Furthermore, typhoid incidence varies over both space and time. The probability for hospital admission and case fatality are also very heterogeneous 19 and are difficult to assess without confirming cases through laboratory culture. Because precise incidence, hospital admission, and mortality rate estimates are difficult to obtain, we identified the minimum values at which TCV vaccination becomes optimal compared with no vaccination in each country, which could be helpful in identifying priority regions to target for vaccination.…”

Section: Discussionmentioning

confidence: 99%

“…Estimates of country-specific vaccine coverage were based on Gavi's demand forecast (appendix pp 18–20). We identified country-specific data on case-fatality rates (eight countries), 19 hospital admission rates (four countries), 20 and costs of vaccine delivery for routine (four countries) and campaign doses (13 countries) 26, 27, 28. For countries without such data, we did random-effects meta-analyses, using all these available studies to inform common estimates (appendix p 22).…”

Section: Methodsmentioning

confidence: 99%

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Cost-effectiveness of routine and campaign use of typhoid Vi-conjugate vaccine in Gavi-eligible countries: a modelling study

Bilcke

Antillón

Pieters

et al. 2019

The Lancet Infectious Diseases

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Summary Background Typhoid fever is a major cause of morbidity and mortality in low-income and middle-income countries. In 2017, WHO recommended the programmatic use of typhoid Vi-conjugate vaccine (TCV) in endemic settings, and Gavi, The Vaccine Alliance, has pledged support for vaccine introduction in these countries. Country-level health economic evaluations are now needed to inform decision-making. Methods In this modelling study, we compared four strategies: no vaccination, routine immunisation at 9 months, and routine immunisation at 9 months with catch-up campaigns to either age 5 years or 15 years. For each of the 54 countries eligible for Gavi support, output from an age-structured transmission-dynamic model was combined with country-specific treatment and vaccine-related costs, treatment outcomes, and disability weights to estimate the reduction in typhoid burden, identify the strategy that maximised average net benefit (ie, the optimal strategy) across a range of country-specific willingness-to-pay (WTP) values, estimate and investigate the uncertainties surrounding our findings, and identify the epidemiological conditions under which vaccination is optimal. Findings The optimal strategy was either no vaccination or TCV immunisation including a catch-up campaign. Routine vaccination with a catch-up campaign to 15 years of age was optimal in 38 countries, assuming a WTP value of at least US$200 per disability-adjusted life-year (DALY) averted, or assuming a WTP value of at least 25% of each country's gross domestic product (GDP) per capita per DALY averted, at a vaccine price of $1·50 per dose (but excluding Gavi's contribution according to each country's transition phase). This vaccination strategy was also optimal in 48 countries assuming a WTP of at least $500 per DALY averted, in 51 with assumed WTP values of at least $1000, in 47 countries assuming a WTP value of at least 50% of GDP per capita per DALY averted, and in 49 assuming a minimum of 100%. Vaccination was likely to be cost-effective in countries with 300 or more typhoid cases per 100 000 person-years. Uncertainty about the probability of hospital admission (and typhoid incidence and mortality) had the greatest influence on the optimal strategy. Interpretation Countries should establish their own WTP threshold and consider routine TCV introduction, including a catch-up campaign when vaccination is optimal on the basis of this threshold. Obtaining improved estimates of the probability of hospital admission would be valuable whenever the optimal strategy is uncertain. Funding Bill & Melinda Gates Foundation, Research Foundation–Flanders, and the Belgian–American Education Foundation.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Cost-effectiveness of routine and campaign use of typhoid Vi-conjugate vaccine in Gavi-eligible countries: a modelling study

Bilcke

Antillón

Pieters

et al. 2019

The Lancet Infectious Diseases

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“…The hospitalization and case fatality rates are particularly influential when estimating the cost-effectiveness of typhoid vaccination strategies [31–33]. However, studies have found considerable heterogeneity in the hospitalization and case fatality rates of typhoid fever cases in different parts of the world [34, 35]. In particular, estimates of the case fatality rate that are derived only from blood culture–confirmed patients may overestimate the mortality rate, as these cases could represent the more severe end of the spectrum of illness.…”

Section: Predicting Typhoid Burden and Vaccine Impactmentioning

confidence: 99%

Generating the Evidence for Typhoid Vaccine Introduction: Considerations for Global Disease Burden Estimates and Vaccine Testing Through Human Challenge

Meiring

Giubilini

Savulescu

et al. 2019

Clinical Infectious Diseases

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Typhoid fever has had a major impact on human populations, with the causative pathogen Salmonella enterica serovar Typhi implicated in many outbreaks through history. The current burden of disease is estimated at 11–18 million infections annually, with the majority of infections located in Africa and South Asia. Data that have been used to estimate burden are limited to a small number of blood-culture surveillance studies, largely from densely populated urban centers. Extrapolating these data to estimate disease burden within and across countries highlights the lack of precision in global figures. A number of approaches have been developed, characterizing different geographical areas by water-based risk factors for typhoid infection or broader measures of health and development to more accurately extrapolate incidence. Recognition of the substantial disease burden is essential for policy-makers considering vaccine introduction. Typhoid vaccines have been in development for >100 years. The Vi polysaccharide (ViPS) and Ty21a vaccines have had a World Health Organization (WHO) recommendation for programmatic use in countries with high burden for 10 years, with 1 ViPS vaccine also having WHO prequalification. Despite this, uptake and introduction of these vaccines has been minimal. The development of a controlled human infection model (CHIM) enabled the accelerated testing of the newly WHO-prequalified ViPS–tetanus toxoid protein conjugate vaccine, providing efficacy estimates for the vaccine, prior to larger field trials. There is an urgency to the global control of enteric fever due to the escalating problem of antimicrobial resistance. With more accurate burden of disease estimates and a vaccine showing efficacy in CHIM, that control is now a possibility.

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“…Untreated, case fatality ratios range from 2.49% in enteric fever,75 0-39.7% in icteric leptospirosis,76 and 0-33% in scrub typhus 77…”

Section: What Are the Possible Complications?mentioning

confidence: 99%

Assessment and initial management of acute undifferentiated fever in tropical and subtropical regions

Bhargava

Ralph

Chatterjee

et al. 2018

BMJ

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Case Fatality Rate of Enteric Fever in Endemic Countries: A Systematic Review and Meta-analysis

Abstract: We conducted a systematic literature review and meta-analysis and estimated the case fatality rate of enteric fever to be 2.49% (95% confidence interval, 1.65%–3.75%; n = 44), 2.5 times higher than what was assumed up until now.

Cited by 33 publications

References 48 publications

Cost-effectiveness of routine and campaign use of typhoid Vi-conjugate vaccine in Gavi-eligible countries: a modelling study

Cost-effectiveness of routine and campaign use of typhoid Vi-conjugate vaccine in Gavi-eligible countries: a modelling study

Generating the Evidence for Typhoid Vaccine Introduction: Considerations for Global Disease Burden Estimates and Vaccine Testing Through Human Challenge

Assessment and initial management of acute undifferentiated fever in tropical and subtropical regions

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