ABSTRACT
The COVID-19 pandemic, which began in 2019, has highlighted the importance of testing and tracking infected individuals as a means of mitigating the spread of the virus. In this context, the development of sensitive and rapid methods for the detection of SARS-CoV-2, the virus responsible for COVID-19, is crucial. Here, a biosensor based on oligonucleotide-gated nanomaterials for the specific detection of SARS-CoV-2 spike protein is presented. The sensing system consists of a nanoporous anodic alumina disk loaded with the fluorescent indicator rhodamine B and capped with a DNA aptamer that selectively binds the SARS-CoV-2 spike protein. The system is initially evaluated using pseudotype virus systems based on vesicular stomatitis virus carrying different SARS-CoV-2 S-proteins on their surface. When the pseudotype virus is present, the cap of the solid is selectively removed, triggering the release of the dye from the pore voids to the medium. The nanodevice demonstrated its ability to detect pseudotype virus concentrations as low as 7.5·103 PFU mL. In addition, the nanodevice is tested on nasopharyngeal samples from individuals suspected of having COVID-19. © 2023 The Authors. Advanced Materials Technologies published by Wiley-VCH GmbH.
ABSTRACT
Study question Can be the SARS-CoV-2 present in human semen samples from patients infected with COVID-19? Summary answer Our research confirms the presence of SARS-CoV-2 in human ejaculate. What is known already In December 2019 WHO was informed of cases of pneumonia of unknown etiology. This was the beginning of a global pandemic that we are suffering still. COVID-19 disease may damage the male reproductive system. The issue of the presence of SARS-CoV-2 in human semen has been addressed in many studies. Most of them concluded that this virus is not present in human semen. However, until now four groups have reported the presence of SASR-CoV-2. It is quite clear that there is an important controversy about the presence of this virus in semen. Further research is needed to clarify this issue. Study design, size, duration Prospective and experimental cohort study to evaluate the presence of SARS-CoV-2 in human semen. Men, COVID-19 disease confirmed, were asked to donate semen sample from July 2020 to March 2021. The patients were recruited with written informed consent. Explicit instructions were given to the correct collection of samples. Participants were interviewed to confirm that collection and transport took place under hygienic conditions. Semen samples were accepted only when instructions were adequately followed. Participants/materials, setting, methods Semen samples were obtained from 50 men (aged 20-51 years) who were diagnosed with qRT-PCR-COVID19 positive (Ct < 40) in nasopharyngeal swab. Patients were closely followed while in hospital or at home. Each semen sample was divided in three aliquots (1 milliliter each) in order to: 1. Perform a spermiogram, 2. Evaluate SARS-CoV-2 with qRT-PCR-COVID19 and 3. Freeze for later use, if necessary. Patients were asked to provide a new specimen if PCR in semen was positive. Main results and the role of chance Patients included in the study showed different types of pneumonia: mild/moderate (N = 46) and severe (N = 6). Patients with severe symptoms had to be placed in intensive care unit. Average time from admission to hospital to sperm collection was 5,8 days. The study did not find any correlation between fresh semen parameters (volume, pH, count and motility) and severity of illness. SARS-CoV-2 was detected in one of fifty (1/50) fresh semen samples. The patient with SARS-CoV-2 in semen had mild symptoms of pneumonia (fever, headache and muscle pain). The patient was asked about how the semen sample was collected. Standards of hygiene during semen collection were confirmed by patient. Presence of SARS-CoV-2 in patient’s semen sample was verified. Limitations, reasons for caution It is possible (though unlikely) that semen sample collection and transportation were incorrect or unhygienic (it was refuted by patient). Besides that, we cannot exclude a false positive in PCR analysis. Although this test has very high specificity with a practical absence of false positives. Wider implications of the findings Although it is evident that the presence of SARS-CoV-2 in human semen is extremely rare, at least four studies confirm this view. In any case the presence of this virus in human semen samples cannot be completely ruled out, on the contrary, further studies are required to confirm this presence. Trial registration number 2020-310-1
ABSTRACT
COVID-19 vaccination has proven to be effective at preventing symptomatic disease but there are scarce data to fully understand whether vaccinated individuals can still behave as SARS-CoV-2 transmission vectors. Based on viral genome sequencing and detailed epidemiological interviews, we report a nosocomial transmission event involving two vaccinated health care-workers (HCWs) and four patients, one of them with fatal outcome. Strict transmission control measures, as during the prevaccination period, must be kept between HCWs and HCWs-patients in nosocomial settings. IMPORTANCE COVID-19 vaccination has proven to be effective at preventing symptomatic disease. Although some transmission events involving vaccinated cases have also been reported, scarce information is still available to fully understand whether vaccinated individuals may still behave as vectors in SARS-CoV-2 transmission events. Here, we report a SARS-CoV-2 nosocomial transmission event, supported on whole genome sequencing, in early March 2021 involving two vaccinated HCWs and four patients in our institution. Strict transmission control measures between HCWs and HCWs - patients in nosocomial settings must not be relaxed, and should be kept as strictly as during the prevaccination period.