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We quantitatively assessed the fit failure rate of N95 respirators according to the number of donning/doffing and hours worn.
A tertiary-care referral center in South Korea.
In total, 10 infection control practitioners participated in the fit test.
The first experiment comprised 4 consecutive 1-hour donnings and fit tests between each donning. The second experiment comprised 2 consecutive 3-hour donnings and fit tests between each donning. The final experiment comprised fit tests after an 1-hour donning or a 2-hour donning.
For 1-hour donnings, 60%, 70%, and 90% of the participants had fit failures after 2, 3, and 4 consecutive donnings, respectively. For 3-hour donnings, 50% had fit failure after the first donning and 70% had failures after 2 consecutive donnings. All participants passed the fit test after refitting whenever fit failure occurred. The final experiment showed that 50% had fit failure after a single use of 1 hour, and 30% had fit failure after a single use of 2 hours.
High fit-failure rates were recorded after repeated donning and extended use of N95 respirators. Caution is needed for reuse (≥1 time) and extended use (≥1 hour) of N95 respirators in high-risk settings such as those involving aerosol-generating procedures. Although adequate refitting may recover the fit factor, the use of clean gloves and strict hand hygiene afterward should be ensured when touching the outer surfaces of N95 respirators for refitting.
Background: Mumps, a contagious disease, is transmissible by respiratory droplet particles and is preventable by vaccination. In South Korea, mandatory vaccination against mumps has markedly reduced its incidence. However, both the incidence and the number of reported cases of mumps have persistently increased in South Korea since 2007. Despite high vaccination rates, mumps outbreaks continue to occur, and many studies have been conducted on mumps seroprevalence in children and adolescents. In comparison, few reports have been published regarding mumps seroprevalence in healthcare workers (HCWs) in South Korea. Objective: We investigated the seroprevalence of HCWs in South Korea. Methods: This study was conducted at Asan Medical Center, a 2,705-bed tertiary-care hospital in Seoul, South Korea, with 8,329 HCWs. In 2018, we performed mumps antibody testing for HCWs. We administered MMR vaccination to all HCWs whose antibody test yielded equivocal or negative results. However, we did not repeat mumps antibody testing after MMR vaccination. Results: In total, 6,055 HCWs (73%) underwent mumps antibody testing. The overall mumps seropositivity rate was 87% (95% CI, 86%–87%). Seropositivity rates of all birth cohorts ranged from 72% to 92%. Mumps seropositivity rates were 88% in HCWs born before 1970, 87% in those born between 1970 and 1989, and 88% in those born between 1990 and 1995 (P = .59). Mumps seropositivity rates for both women and men HCWs were 87% (3,770 of 4,311 women and 1,517 of 1,744 men); the difference was not statistically significant (P = .62). The overall mumps seropositivity rate was 87%, which was above the herd immunity threshold of 75%–86%. Conclusions: Our results revealed that the overall mumps seropositivity rate in South Korean HCWs was above the herd immunity threshold. On the basis of this finding, we recommend that MMR vaccination after serologic testing may be a more reasonable approach than universal MMR vaccination alone in Korea.
Background: Measles is a highly contagious disease that is transmissible by airborne particles but is preventable by vaccination. South Korea has maintained a highly immunized adult population; however, small local outbreaks of measles continued to occur, and there have been some reports of pockets of underimmunity among the young adult population. It is important to know the seroepidemiology of healthcare workers (HCWs) for policy-making process, but data on the seroprevalence of measles in HCWs in South Korea are limited. Methods: We investigated the seroprevalence of HCWs at Asan Medical Center, a 2,705-bed tertiary-care hospital in Seoul, South Korea, with 8,329 HCWs. In 2014, after an outbreak of measles occurred in a university in Seoul, Asan Medical Center required measles IgG tests for all HCWs born in and after 1967 for point-prevalence surveillance. In addition, we have routinely performed measles antibody test for new HCWs since 2014. In 2018, antibody tests were administered to HCWs who were born before 1967 or who had taken a leave of absence in 2014. We provided MMR vaccination to all HCWs whose antibody tests yielded negative results. Results: In total, 7,411 HCWs (89%) underwent measles antibody tests from 2014 to 2018. The overall seropositivity was 73% (95% CI, 72%–74%); seroprevalence was 73% in HCWs born in of after 1967, whereas the seroprevalence in HCWs born before 1967 was 98%. The seroprevalence sharply decreased from 85% in the 1986 birth cohort to 42% in the 1995 birth cohort. Conclusions: In conclusion, the proportion of measles-susceptible individuals was substantially high in HCWs, especially in young adults. Because the impact of measles outbreak in healthcare facilities would be critical, a policy regarding routine serologic screening followed by measles vaccination or routine measles vaccination in healthcare facilities should be considered, especially for young Korean HCWs.
The “organizational life” is an important part of the daily existence of North Koreans. Every adult in North Korea has to be a participant in a multitude of rituals that serve a dual purpose of surveillance and indoctrination. In this article, we describe how the organizational life is arranged and also explain the ways it contributes to maintaining the domestic stability of North Korea and to manufacturing consent for the current regime. The study is based largely on refugee interviews.
We investigated continuous fabrication of a large area 2-D metamaterial comprising a metal dot array on a dielectric coated substrate. We demonstrated patterning of metal dots arrays of varying patterns and shapes with diameter of about 2.5 μm and metal-to-metal spacing from 0.3 to 2.5 μm using a nano-imprinting stamp on a roller. The pattern was first fabricated on a standard photolithography mask, reproduced onto a silicon wafer master mold, and then transferred to a flexible polymer mold that was wrapped around a metal roller. The method was used to pattern a thin Al layer on top of SiO2 on a flexible polymer substrate. The aluminum was coated with a resist and the roller moved over the substrate with adjustable speed and pressure to imprint the fine pattern into the resist. The resist was cured, and a very thin layer of residual resist was removed by RIE, followed by a standard etching treatment for patterning the aluminum layer.
The as-etched pattern had very few defects and the optical properties of the metamaterial were excellent and correlated well with simulations. This work has shown that low cost, rapid roll-to-roll processing of 2-D metamaterial structures is possible.
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