Estimating case fatality risk of severe Yellow Fever cases: systematic literature review and meta-analysis

Abstract

Background Case fatality risk (CFR), commonly referred to as a case fatality ratio or rate, represents the probability of a disease case being fatal. It is often estimated for various diseases through analysis of surveillance data, case reports, or record examinations. Reported CFR values for Yellow Fever vary, offering wide ranges. Estimates have not been found through systematic literature review, which has been used to estimate CFR of other diseases. This study aims to estimate the case fatality risk of severe Yellow Fever cases through a systematic literature review and meta-analysis. Methods A search strategy was implemented in PubMed and Ovid Medline in June 2019 and updated in March 2021, seeking reported severe case counts, defined by fever and either jaundice or hemorrhaging, and the number of those that were fatal. The searches yielded 1,133 studies, and title/abstract review followed by full text review produced 14 articles reporting 32 proportions of fatal cases, 26 of which were suitable for meta-analysis. Four studies with one proportion each were added to include clinical case data from the recent outbreak in Brazil. Data were analyzed through an intercept-only logistic meta-regression with random effects for study. Values of the I2 statistic measured heterogeneity across studies. Results The estimated CFR was 39 % (95 % CI: 31 %, 47 %). Stratifying by continent showed that South America observed a higher CFR than Africa, though fewer studies reported estimates for South America. No difference was seen between studies reporting surveillance data and studies investigating outbreaks, and no difference was seen among different symptom definitions. High heterogeneity was observed across studies. Conclusions Approximately 39 % of severe Yellow Fever cases are estimated to be fatal. This study provides the first systematic literature review to estimate the CFR of Yellow Fever, which can provide insight into outbreak preparedness and estimating underreporting.

Epidemiology of yellow fever virus in humans, arthropods, and non-human primates in sub-Saharan Africa: A systematic review and meta-analysis

“…The estimated CFR of YFV in humans identified in this review is consistent with that recently reported in a global review with a CFR of 36% for Africa [77]. Such a high CFR could be due to delays or deterrents in seeking care during the early less sever phase of the disease or delayed clinical diagnosis of cases [62,76].…”

“…Such a high CFR could be due to delays or deterrents in seeking care during the early less sever phase of the disease or delayed clinical diagnosis of cases [62,76]. It should also be noted that African population is more at risk of contracting the yellow fever virus and of developing severe forms and death due to a low rate of vaccination coverage and daily activities that bring them closer to vectors such as agriculture, livestock, hunting, and deforestation [77][78][79][80]. Also, the existence in Africa of other health conditions such as malnutrition, tuberculosis, malaria and, HIV are other factors that could be associated with this high of YFV CFR [81][82][83].…”

Epidemiological profile, trend, seasonality, and factors associated with Yellow fever disease and barriers to vaccination: a retrospective observational study of multi-season national surveillance data in Nigeria, 2017 - 2021

“…Infected persons present with a broad spectrum of clinical disease, ranging from asymptomatic infections and mild febrile illness to severe disease and death. It is estimated that 15-25% of infected symptomatic persons progress to severe disease with a case fatality rate of 20-60% [6,14].…”

Factors Involved in the Apoptotic Cell Death Mechanism in Yellow Fever Hepatitis

“…Viruses 2022, 14, 1204 2 of 10 been a concern for public authorities owing to the low vaccination coverage in non-endemic and endemic areas [1][2][3][4]. Epidemiologically, fatality in severe cases of YF is estimated to be approximately 31-45%, indicating the public health importance of this disease [5].…”

“…The virus is then released into the bloodstream and is transported to multiple organs such as the kidney, heart, spleen, lung, and liver. The liver is the most affected organ in humans [5][6][7].…”