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Objectives: We aimed to determine epidemiological characteristics and serologic markers among chronically hepatitis B virus (HBV)-infected pregnant women during the assessment of tenofovir disoproxil fumarate (TDF) prescription in Vietnam. Methods: We consecutively recruited 375 pregnant women with chronic HBV (cHBV) infection at week 25±2 of pregnancy, at which time they were assessed for TDF use as pre-prophylaxis and/or pre-treatment at the Hospital for Tropical Diseases in southern Vietnam during December 2019-April 2021. Demographic characteristics, serological biomarkers, and prenatal liver ultrasounds were obtained through interviews and reviews of medical records. Results: The median age of pregnant women was 29 years (interquartile range: 26-32). More than half of pregnant women (208/375; 55.5%) started TDF for prevention of mother-to-child transmission of HBV and/or treatment of chronic hepatitis B (CHB). Among the pregnant women initiating TDF, 96.1% (198/206) tested positive for hepatitis B e antigen, and 21.6% (45/208) had quantitative hepatitis B surface antigen (qHBsAg) ≤104 IU/mL. A relatively strong correlation between qHBsAg and HBV deoxyribonucleic acid (DNA) (r = 0.81; 95% CI: 0.76-0.85) was observed in pregnant women starting TDF. Conclusions: Our results demonstrate the high need for TDF prescription for prevention and/or treatment purposes in pregnant women with cHBV infection. Pregnant women with qHBsAg levels ≤104 IU/mL may prioritize HBV DNA testing over qHBsAg to decide on TDF prescription.
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We studied the development and persistence of neutralising antibodies against SARS-CoV-2 ancestral strain, and Delta and Omicron (BA.1 and BA.2) variants in Vietnamese healthcare workers (HCWs) up to 15 weeks after booster vaccination. We included 47 HCWs with different pre-existing immune statuses (group 1 (G1): n=21, and group 2 (G2): n=26 without and with prior breakthrough Delta variant infection, respectively). The study participants had completed primary immunisation with ChAdOx1-S and booster vaccination with BNT162b2. Neutralising antibodies were measured using a surrogate virus neutralisation assay. Of the 21 study participants in G1, neutralising antibodies against ancestral strain, Delta variant, BA.1 and BA.2 were (almost) abolished at month 8 after the second dose, but all had detectable neutralising antibodies to the study viruses at week two post booster dose. Of the 26 study participants in G2, neutralising antibody levels to BA.1 and BA.2 were significantly higher than those to the corresponding viruses measured at week 2 post breakthrough infection and before the booster dose. At week 15 post booster vaccination, neutralising antibodies to BA.1 and BA.2 dropped significantly, with more profound changes observed in those without breakthrough Delta variant infection. Booster vaccination enhanced neutralising activities against ancestral strain and Delta variant, as compared to those induced by primary vaccination. These responses were maintained at high levels for at least 15 weeks. Our findings emphasise the importance of the first booster dose in producing cross-neutralising antibodies against Omicron variant. A second booster dose might be needed to maintain long-term protection against Omicron variant.
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BACKGROUND: Recent outbreaks of avian influenza A (H5N1) in poultry throughout Asia have had major economic and health repercussions. Human infections with this virus were identified in Vietnam in January 2004. METHODS: We report the clinical features and preliminary epidemiologic findings among 10 patients with confirmed cases of avian influenza A (H5N1) who presented to hospitals in Ho Chi Minh City and Hanoi, Vietnam, in December 2003 and January 2004. RESULTS: In all 10 cases, the diagnosis of influenza A (H5N1) was confirmed by means of viral culture or reverse transcriptase-polymerase chain reaction with primers specific for H5 and N1. None of the 10 patients (mean age, 13.7 years) had preexisting medical conditions. Nine of them had a clear history of direct contact with poultry (median time before onset of illness, three days). All patients presented with fever (temperature, 38.5 to 40.0 degrees C), respiratory symptoms, and clinically significant lymphopenia (median lymphocyte count, 700 per cubic millimeter). The median platelet count was 75,500 per cubic millimeter. Seven patients had diarrhea. In all patients, there were marked abnormalities on chest radiography. There was no definitive evidence of human-to-human transmission. Eight patients died, one patient has recovered, and one is recovering. CONCLUSIONS: Influenza A (H5N1) infection, characterized by fever, respiratory symptoms, and lymphopenia, carries a high risk of death. Although in all 10 cases the infection appears to have been acquired directly from infected poultry, the potential exists for genetic reassortment with human influenzaviruses and the evolution of human-to-human transmission. Containment of influenza A (H5N1) in poultry throughout Asia is therefore urgently required.