Background & Aim: This study aims to evaluate the prevalence of undiagnosed hepatitis delta in southern Spain (Andalusia) and assess the effectiveness and cost-efficiency of implementing reflex testing for hepatitis D detection in HBsAg-positive patients. Patient & Methods: A multicenter ambispective study was conducted in 17 hospitals in Andalusia. The retrospective phase analyzed diagnostic processes for hepatitis delta from January 2018 to June 2022, focusing on HBsAg-positive patients. The prospective phase, from October 2022 to March 2023, implemented reflex testing, performing anti-HDV serology on all HBsAg-positive patients without prior testing. HDV RNA testing was conducted on those who tested positive for anti-HDV. Results: In the retrospective phase, out of 18,583 HBsAg-positive patients, anti-HDV tests were performed on 3,436 (18%), identifying 205 (6%) positive cases. HDV RNA was tested in 158 (77%) anti-HDV-positive patients, with 69 (44%) testing positive. In the prospective phase, out of 2,384 HBsAg-positive patients without prior anti-HDV testing, 2,293 (96%) were tested, identifying 109 (4.7%) positive cases. HDV RNA was analyzed in 97 (89%) anti-HDV-positive patients, with 30 (31%) testing positive. Reflex testing increased anti-HDV detection by 77%, resulting in a fourfold increase in detecting anti-HDV-positive patients and a threefold increase in detecting HDV RNA-positive patients, reducing undiagnosed HDV RNA-positive cases to 4% compared to 45% with clinical practice. Cost analysis indicated a saving of €265,954 with reflex testing. Discussion: Reflex testing significantly improves HDV detection and reduces healthcare costs. It simplifies the diagnostic process, increasing the detection rate of hidden chronic hepatitis delta patients and proving to be an efficient strategy for managing chronic hepatitis B patients.

Background: SARS-CoV-2 variation represents a serious challenge to current COVID-19 vaccines. Recent reports suggest that B.1.351 and other variants may escape the neutralization activity of the antibodies generated by current vaccines. Methods: Ninety-nine healthcare workers undertaking BNT162b2 mRNA vaccination were sampled at baseline, on the day of the second dose, and 14 days after the latter. Neutralization activity against SARS-CoV-2 B.1, B.1.1.7 and B.1.351 was investigated using a Vero-E6 model. Results: Eleven of the study participants had prior infection with SARS-CoV-2. Neutralization titers against the B.1 and the B.1.1.7 variants were not statistically different and were significantly higher than titers against the B.1.351 variant across pre-exposed and non-pre-exposed vaccinated individuals ( p<0.01). While all vaccinated individuals presented neutralizing antibodies against B.1 and B 1.1.7 after the second dose, 14% were negative against B.1.351, and 76% had low titers (1/20-1/80). Pre-exposed vaccinated individuals showed higher titers than non-pre-exposed after the first (median titers of 1/387 versus 1/28, respectively) and the second doses (1/995 versus 1/703, respectively). As high as 72% of the pre-exposed vaccinees presented titers >1/80 after a single dose, while only 11% of non-exposed vaccinated individuals had titers >1/80. Conclusions: BNT162b2 mRNA-induced antibodies show a lower in vitro neutralizing activity against B.1.351 variant compared to neutralization against B.1.1.7 or B.1 variants. Interestingly, for individuals pre-exposed to SARS-CoV-2, one dose of BNT162b2 mRNA may be adequate to produce neutralizing antibodies against B.1.1.7 and B.1, while two doses of BNT162b2 mRNA provide optimal neutralizing antibody response against B.1.351 too.