Background Data on breakthrough SARS-CoV-2 Delta variant infections in vaccinated individuals are limited. Methods We studied breakthrough infections among Oxford-AstraZeneca vaccinated healthcare workers in an infectious diseases hospital in Vietnam. We collected demographic and clinical data alongside serial PCR testing, measurement of SARS-CoV-2 antibodies, and viral whole-genome sequencing. Findings Between 11 th –25 th June 2021 (7-8 weeks after the second dose), 69 staff tested positive for SARS-CoV-2. 62 participated in the study. Most were asymptomatic or mildly symptomatic and all recovered. Twenty-two complete-genome sequences were obtained; all were Delta variant and were phylogenetically distinct from contemporary viruses obtained from the community or from hospital patients admitted prior to the outbreak. Viral loads inferred from Ct values were 251 times higher than in cases infected with the original strain in March/April 2020. Median time from diagnosis to negative PCR was 21 days (range 8–33). Neutralizing antibodies (expressed as percentage of inhibition) measured after the second vaccine dose, or at diagnosis, were lower in cases than in uninfected, fully vaccinated controls (median (IQR): 69.4 (50.7-89.1) vs. 91.3 (79.6-94.9), p=0.005 and 59.4 (32.5-73.1) vs. 91.1 (77.3-94.2), p=0.002). There was no correlation between vaccine-induced neutralizing antibody levels and peak viral loads or the development of symptoms. Interpretation Breakthrough Delta variant infections following Oxford-AstraZeneca vaccination may cause asymptomatic or mild disease, but are associated with high viral loads, prolonged PCR positivity and low levels of vaccine-induced neutralizing antibodies. Epidemiological and sequence data suggested ongoing transmission had occurred between fully vaccinated individuals. Funding Wellcome and NIH/NIAID

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As of 13 July 2016, 13 countries have reported fetal Zika virus (ZIKV) infection. Here we report a case of fetal ZIKV infection that resulted from an infection originating in Vietnam. Funding StatementThe author(s) received no specific funding for this work. ReportOn March 30, 2016, a woman at eight weeks of pregnancy presented with one day of rash, conjunctivitis, and fatigue to a hospital in Ho Chi Minh City, Vietnam. Blood samples were collected and tested for ZIKV using primers and probes as previously described 1 . Real-time RT-PCR was positive for ZIKV and negative for rubella virus. Two days after the initial blood draw, a repeat blood sample and a urine sample were collected. The urine sample tested positive for ZIKV by RT-PCR, but the later blood sample was negative. Viral RNA isolated from the urine sample was amplified using previously defined primers ZIKVENVF and ZIKVENVR and sequenced 2 . Sequence results indicate that the strain isolated from this patient is most closely related to those isolated previously in Malaysia (2012) and French Polynesia (2013).The patient reported no recent travel. Her husband had been working in Malaysia, returning to visit Vietnam from March 16th to 19th. He reported no symptoms in the month prior to his visit to Vietnam, and no cases of Zika had been reported in the area where he worked. The patient denied any sexual contact 12 days prior to the onset of symptoms, the assumed longest incubation period for Zika 5 . The patient's two-year old daughter experienced similar symptoms three days before her mother, however samples were only collected after the resolution of symptoms and were negative by RT-PCR.Seven days after her onset of symptoms the patient was seen in a prenatal clinic for counseling regarding ZIKV infection during pregnancy. A 8-week ultrasound performed the week before had shown a viable fetus, however at the visit, a repeat ultrasound was performed that indicated fetal demise. The following day a suction aspiration abortion was performed, during which samples were taken from both the placenta and fetus. Both the fetal and placental samples were positive by ZIKV RT-PCR, while negative for rubella.The previous lack of reported microcephaly in Asia and Africa had led to speculation regarding ZIKV strain differences in relation to teratogenicity. This case indicates that the viral strain present in Asia also has the ability to cause infection in utero. It is possible fetal infection was not previously noted in Asia due to limited surveillance systems for birth defects, or to early in life infection that provides immunity at child bearing age, or possibly, due to a more gradual spread of the disease.This report is one of the first documented cases of ZIKV infection in Vietnam, however it is likely that infection has been occurring for many years without detection or diagnosis. Since the increased awareness of the risk of ZIKV infection, three tourists have been identified who were infected while traveling in Veitnam and two local cases have been conf...

We studied the immunogenicity of the Oxford-AstraZeneca vaccine in health-care workers of a major infectious diseases hospital in Vietnam. We measured neutralizing antibodies before and 14 days after each dose, and at day 28 and month 3 after dose 1. A total of 554 workers (136 men and 418 women; age range, 22–71 years; median age, 36 years) participated with the study. Of the 144 participants selected for follow-up after dose 1, 104 and 94 gave blood for antibody measurement at weeks 6 and 8, and at month 3 after dose 1, respectively. The window time between the two doses was 6 weeks. At baseline, none had detectable neutralizing antibodies. After dose 1, the proportion of participants with detectable neutralizing antibodies increased from 27.3% (151 of 554) at day 14 to 78.0% (432 of 554) at day 28. Age correlated negatively with the development and the levels of neutralizing antibodies. However, at day 28, these differences were less profound, and women had a greater seroconversion rate and greater levels of neutralizing antibodies than men. After dose 2, these age and gender associations were not observable. In addition, the proportion of study participants with detectable neutralizing antibodies increased from 70.2% (73 of 104) before dose 2 (week 6, after dose 1) to 98.1% (102 of 104) 14 days later. At month 3, neutralizing antibodies decreased and 94.7% (89 of 94) of the study participants remained seropositive. The Oxford-AstraZeneca COVID-19 vaccine is immunogenic in Vietnamese health-care workers. These data are critical to informing the deployment of the COVID-19 vaccine in Vietnam and in Southeast Asia, where vaccination coverage remains inadequate.

In this study, TiO2 nanowires on TiO2 nanotubes arrays (TNWs/TNAs) and Au-decorated TNWs/TNAs nanostructures are designed and fabricated as a new type of photoanode for photoelectrochemical (PEC) water splitting. The TNWs/TNAs were fabricated on Ti folds by anodization using an aqueous NH4F/ethylene glycol solution, while Au nanoparticles (NPs) and Au nanorods (NRs) were synthesized by Turkevich methods. We studied the crystal structure, morphology, and PEC activity of four types of nanomaterial photoanodes, including TNWs/TNAs, Au NPs- TNWs/TNAs, Au NRs-TNWs/TNAs, and Au NPs-NRs-TNWs/TNAs. The TiO2 and Au-TiO2 samples exhibited pure anatase phase of TiO2 with (0 0 4), (1 0 1), and (1 0 5) preferred orientations, while Au-TiO2 presented a tiny XRD peak of Au (111) due to a small Au decorated content of 0.7 ± 0.2 at.%. In addition, the samples obtained a well-defined and uniformed structure of TNAs/TNWs; Au NPs (size of 19.0 ± 1.9 nm) and Au NRs (width of 14.8 ± 1.3 nm and length of 99.8 ± 15.1 nm) were primarily deposited on TNWs top layer; sharp Au/TiO2 interfaces were observed from HRTEM images. The photocurrent density (J) of the photoanode nanomaterials was in the range of 0.24–0.4 mA/cm2. Specifically, Au NPs-NRs- decorated TNWs/TNAs attained the highest J value of 0.4 mA/cm2 because the decoration of Au NPs and Au NRs mixture onto TNWs/TNAs improved the light harvesting capability and the light absorption in the visible-infrared region, enhanced photogenerated carriers’ density, and increased electrons’ injection efficiency via the localized surface plasmon resonance (LSPR) effect occurring at the Au nanostructures. Furthermore, amongst the investigated nanophotocatalysts, the Au NPs-NRs TNWs/TNAs exhibited the highest photocatalytic activity in the degradation of methylene blue with a high reaction rate constant of 0.7 ± 0.07 h−1, which was 2.5 times higher than that of the pristine TNWs/TNAs.