Hepatitis B infections among blood donors in England between 2009 and 2018: Is an occult hepatitis B infection a risk for blood safety?

Abstract

Introduction Hepatitis B virus (HBV) is one of the most frequent infections identified in blood donors in England and represents an ongoing blood safety risk. We have analyzed markers of HBV infections in blood donors in England between 2009 and 2018 and used these to estimate the likelihood of non‐detection of occult HBV infection (OBI). Methods We collected epidemiological, virological, and genotyping information on HBV cases identified in England, 2009–2018. The estimated risk of non‐detection and likely transmission of OBI were compared to lookback and transfusion‐transmitted infections surveillance data. Results Six‐hundered and fifty‐five HBV‐infected blood donors were identified in England during the 10‐year period; 598 chronic, 32 acute, and 25 occult HBV infections. However, most donors with chronic and occult infections were born in Eastern Europe, Africa, or Asia (451/544, 83% and 14/24, 58%); acute infections were largely seen in UK‐born donors (19/28, 68%). Genotyping of 266 HBV‐positive samples revealed five genotypes (A–E), reflecting ethnicity and country of birth. Most OBIs were identified in repeat donors (19/25); lookback data identified a transmission rate of 8.3%. It is estimated that at least 13 potentially infectious donations from donors with OBI remain undetected annually, equating to an overall residual transmission risk of 3.1 per million donations using our current screening strategy of HBsAg screening with HBV nucleic acid testing (NAT) in pools of 24. Conclusions OBI accounted for the majority of the HBV residual risk in England. Further cost–benefit analysis is required to estimate if our current HBV screening strategy should be changed.

Residual risk of transfusion‐transmitted hepatitis B virus (TT‐HBV) infection by NAT‐screened blood components: A review of observed versus modeled infectivity from donors with window period and occult HBV infections

“…3 However, the documented infectivity rates of MP-NAT nonreactive/ID-NAT yield donations from WP versus OBI transfusions in the Japanese lookback study of Satake et al 11 were substantially lower-50% (11/22) versus 3% (1/33). The modeled OBI infectivity rates were also considerably higher than the rates of 2%-8% observed in other systematic lookback studies in Australia, 21,22 the Netherlands, 23 and the United Kingdom, 26 but comparable to the estimated rate of 36% (range 24-85% for RBC and FFP) in a European lookback study. 18 In this latter study of Allain et al, the estimated OBI transmission rates of RBC and FFP transfusions were comparable to the percentages predicted by the Weusten model, 5 but this study was enriched by multiple donations from a few donors known to be infectious.…”

“…However, the modeled absolute risk was considerably higher than the rates observed in five of the six reviewed lookback studies. 11,18,[21][22][23]26 According to our modeling based on ID 50 values of 3.16 (1-10) versus 316 (100-1000) virions in WP and OBI stages, we predicted that 90 (72-100)% of the MP20-NAT nonreactive/ID-NAT reactive WP donations in Japan would be infectious and 16 % to 51 (32-81)% of OBI donations would transmit HBV depending on the transfusion plasma volume in the blood component (with the assumption that 50% of OBI NAT yield donations would be noninfectious due to presence of neutralizing anti-HBs antibodies). 3 However, the documented infectivity rates of MP-NAT nonreactive/ID-NAT yield donations from WP versus OBI transfusions in the Japanese lookback study of Satake et al 11 were substantially lower-50% (11/22) versus 3% (1/33).…”

“…11,17,18,[21][22][23]26 In a European multi-center lookback study, Allain and coinvestigators 18 estimated a significantly higher OBI transmission rate (36%) than the rates observed in the other more systematic national lookback studies, which ranged from 2% to 8%. 11,17,[21][22][23]26 Of particular interest, the Japanese lookback study of Satake and colleagues 11 was highly informative in comparing infectivity of ID-NAT-positive donations that were anti-HBc-positive (OBI) and anti-HBcnegative (WP). This study found a >10-fold higher HBV transmission rate by WP donations (11/22) than by OBI donations (1/33) or by anti-HBs-negative OBI donations (1/16).…”

“…This allowed us to compare the relative proportion of TT-HBV risk from WP versus OBI donations in our model with the proportions observed in TT-HBV studies. [11][12][13][14][15][17][18][19][20][21][22][23][24][25][26] 3 | RESULTS…”

“…16 However, over the last decade, additional HBV infectivity studies have been published. [17][18][19][20][21][22][23][24][25][26] One report challenged our assumption of HBV infectivity in that it claimed that the minimum infectious dose in OBI donations should be revised to a much lower number of 16 virions. 24 The aim of the current manuscript is to examine whether our assumption of a 100-fold difference in infectivity (and ID 50 ) between WP and OBI donations is supported by the observed TT-HBV infection data reviewed in this report.…”