The isolation of infected individuals and quarantine of their contacts are usually employed to mitigate the transmission of SARS-CoV-2. Although 14-day isolation of infected individuals could effectively reduce the risk of subsequent transmission, it also substantially impacts the patient's psychological and emotional well-being. It is, therefore, vital to investigate how the isolation duration could be shortened when effective vaccines are available. Here, an individual-based modeling approach was employed to estimate the likelihood of secondary infections and the likelihood of an outbreak following the isolation of a primary case for a range of isolation periods. Our individual-based model integrated the viral loads and infectiousness profiles of vaccinated and unvaccinated infected individuals. The effects of waning vaccine-induced immunity against infection were also considered. By simulating the transmission of the SARS-CoV-2 Delta (B.1.617.2) variant in a community, we found that in the baseline scenario in which all individuals were unvaccinated and nonpharmaceutical interventions were not used, there was an approximately 3% chance that an unvaccinated individual would lead to at least one secondary infection after being isolated for 14 days, and a sustained chain of transmission could occur with a less than 1% chance. With the outbreak risk equivalent to that of the 14-day isolation in the baseline scenario, we found that the isolation duration could be shortened to 7.33 days (95% CI 6.68–7.98) if 75% of people in the community were fully vaccinated with the BNT162b2 vaccine within the last three months. In the best-case scenario in which all individuals in the community are fully vaccinated, isolation of Delta variant-infected individuals may no longer be necessary. However, to keep the outbreak risk lower than 1%, a booster vaccination may be necessary three months after full vaccination.
Background: Isolation of infected individuals and quarantine of their contacts are usually employed to mitigate the transmission of SARS-CoV-2. While 14-day isolation of infected individuals could effectively reduce the risk of subsequence transmission, it also significantly impacts the patient's financial, psychological, and emotional well-being. It is, therefore, vital to investigate how the isolation duration could be shortened when effective vaccines are available and in what circumstances we can live with COVID-19 without isolation and quarantine. Methods: An individual-based modeling approach was employed to estimate the likelihood of secondary infections and the likelihood of an outbreak following the isolation of an index case for a range of isolation periods. Our individual-based model integrates the viral load and infectiousness profiles of vaccinated and unvaccinated infected individuals. The effects of waning vaccine-induced immunity against Delta and Omicron variant transmission were also investigated. Results: In the baseline scenario in which all individuals are unvaccinated, and no nonpharmaceutical interventions are employed, there is a chance of about 3% that an unvaccinated index case will make at least one secondary infection after being isolated for 14 days, and a sustained chain of transmission can occur with a chance of less than 1%. We found that at the outbreak risk equivalent to that of 14-day isolation in the baseline scenario, the isolation duration can be shortened to 7.33 days (95% CI 6.68-7.98) if 75% of people in the community are fully vaccinated during the last three months. In the best-case scenario in which all individuals in the community are fully vaccinated, isolation of infected individuals may no longer be necessary, at least during the first three months after being fully vaccinated, indicating that booster vaccination may be required after being fully vaccinated for three to four months. Finally, our simulations showed that the reduced vaccine effectiveness against Omicron variant transmission does not much affect the risk of an outbreak if the vaccine effectiveness against infection is maintained at a high level via booster vaccination. Conclusions: The isolation duration of a vaccine breakthrough infector could be safely shortened if a majority of people in the community are immune to SARS-CoV-2 infection. A booster vaccination may be necessary three months after full vaccination to keep the outbreak risk low.
Riceberry brown rice is regarded as a source of various nutrients; often richer than white rice. Non-thermal plasma has recently been gaining a role for improving properties of cereal grains, especially brown rice. A number of methods of plasma treatment has been proposed including discharges as capacitive coupled plasma (CCP) and inductive coupled plasma (ICP). ICP has two operation modes as capacitive (E-mode) and inductive (H-mode) discharge with rather distinct characters. In this study we have focused on using ICP Ar/O2 plasma in both E-and H mode for plasma treatment on riceberry brown rice. The input power for plasma generation were set to 50 and 250 W for E-and H-mode, respectively. Plasma in H-mode was having higher plasma density than that in E-mode, as observed in the optical emission spectrum. The surface morphology of riceberry brown rice before and after Ar/O2 plasma treatment was evaluated using a scanning electron microscope without or with an energy dispersive spectroscopy (SEM and SEM/EDS). It has been found that the bran layer was richer in elemental compositions than the endosperm. The surface of rice sample was found to be etched and more porous after plasma treatment. The Ar/O2 plasma in H-mode was observed to offer higher effect. The surface contact angle was found to decrease from 120.1o ± 0.9o in untreated samples to 79.3o ± 0.6o and 99.2o ± 0.8o in plasma treated samples on E-and H-mode, respectively.
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