Background: Laboratory staff is at higher risk of infection owing to the handling and testing of coronavirus disease 2019 (COVID-19) patient samples. Reviewing the existing risk assessment and improving risk management are essential for preventing laboratory acquired infections (LAIs) related to Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) testing during the COVID-19 epidemic. We present herein the steps taken to prevent LAIs related to SARS-CoV-2 testing in a tertiary care hospital in Vietnam. Methods: A SARS-CoV-2-focused risk assessment exercise was conducted for laboratory processes and workflow. Risk management strategies, including engineering, administrative and operations control procedures, were established. Standard operating procedure (SOP), staff training, COVID-19 symptom reporting, enhanced cleaning and decontamination, and inventory monitoring protocols were implemented. Sample reception and results reported from February 1, 2020 to September 17, 2020 were documented. Results: Based on risk assessment, a risk management strategy for SARS-CoV-2 testing was developed. This strategy includes the use of dedicated facility, instrument, and cold chain units for testing; SOPs; training (testing, decontamination and cleaning staff); the introduction of biosafety level (BSL)2+ laboratory practices; enhanced cleaning protocols for testing; and the assigning of additional staff for testing and safety system implementation. In total, 38,377 (daily mean and range: 166; 3 – 2,377) samples were received, including 301 (0.8%) samples that were rejected. The turnaround time (median ± standard deviation (SD)) was 3.54 ± 2.97 days. Altogether, 32 staff members were involved with SARS-CoV-2 testing and biosafety management, and there were no reports of COVID-19 symptoms among them. Conclusion: For epidemics and outbreak diagnostics, risk assessment and risk management strategies are important for the prevention of LAIs. Clear instruction on revised risk management protocols, necessary training, and leadership in risk management strategy implementation are essential.
This paper presents the variations of the rate of change of Total Electron Content (TEC) index (ROTI), characterizing the occurrence of ionospheric plasma irregularities over Vietnam and neighboring countries in the Southeast Asian region using the continuous GPS data during the 2008-2018 period. The results showed that the occurrence of strong ROTI in all stations is maximum in equinox months March/April and September/October and depends on solar activity. The ROTI is weak during periods of low solar activity and strong during periods of high solar activity. There is an asymmetry between the two equinoxes. During maximum and declining phases of 2014-2016, occurrence rates in March equinox are larger than in September equinox, but during the descending period of 2010-2011, the occurrence rates in September equinox at almost all stations are larger than in March equinox. The correlation coefficients between the monthly occurrence rate of irregularities and the F10.7 solar index at the stations in the equatorward EIA crest region are higher than at those in the magnetic equatorial and the poleward EIA crest regions. The irregularity occurrence is high in the pre-midnight sector, maximum between 2000 LT to 2200 LT. The maximum irregularity occurrence is located around 4-5° degrees in latitude equator-ward away from the anomaly crests.
The quasi-biennial oscillation (QBO) signals at two Equatorial ionization anomaly (EIA) crests of the ionosphere have been studied using the continuous GNSS network data in Vietnam and adjacent regions during the 2008- 2021 period. The monthly mean EIA crests amplitudes are calculated. The Lomb-Scargle periodogram method was applied to the residuals of the EIA crests magnitudes, DTEC, which are obtained from subtracting the fittings with solar index, F10.7. The Lomb-Scargle spectrum shows the quasi-biennial component in the residuals DTEC with the picks at 18, 25, and 29-30 months. The ionosphere QBO at two EIA crests was found out by the band-pass filter centered at 25 months with haft-power points at 17 and 33 months. The zonal wind data at 50 hPa (~ 20 km) of the tropical equatorial stratosphere is used as the stratosphere QBO (SQBO) to consider the relationship between the SQBO and the obtained ionosphere QBO. The direct comparison and the cross wavelet transform of the SQBO and ionosphere QBO data series show that during 2008-2009, the ionosphere QBO signal is low, the SQBO and ionosphere QBO are in phase during the 2010-2013 and 2018-2021 periods, but anti-phase during the 2014-2017 period. For the 2010-2013, 2014-2017 and 2018-2021 periods, the correlation coefficients are 0.623, 0.637, -0.646 in the northern crest, and 0.571, 0.53, -0.530 in the southern crest, respectively. Furthermore, we also observed that the SQBO and the ionosphere QBO signals were shortened during the 2015-2016 period, approximately 1.5 years. Previous studies showed that the ENSO (El Niño - Southern Oscillation) warm phase, also known as El-Niño existed during 2015-2016. The results of this study allow us to assume that the SQBO influences the ionosphere QBO. Our results show that the SQBO is the main factor affecting the ionospheric QBO at two EIA crests. However, the physical theoretical interpretation of the mechanisms of action is a challenge for scientists and requires further research.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.