ABSTRACT
Background: This is a case report on a cluster infection of novel severe acute respiratory syndrome coronavirus 2 delta AY.1 variant at an accommodation facility and the subsequent attempts to isolate individuals who tested positive. Methods The background that facilitated this cluster was investigated, and the conditions in which infection was established, the infection route, and the effectiveness of routine measures were evaluated. Ninety-nine staff members had been working at the accommodation facility at the time of infection, and it was estimated that 10 members were infected with the delta AY.1 variant. Results Our results suggest that infection of staff from a patient staying overnight should be excluded. The factors contributing to the cluster infection involved short-distance conversations with individuals wearing non-woven three-layer masks moved out of position (non-woven) and gathering together with individuals wearing non-woven masks in hypoventilated conditions. Our findings also indicate that this variant is possibly airborne and can infect individuals in enclosed spaces with poor ventilation, even when either infected or exposed individuals wear non-woven masks. Conclusions The routine maintenance of systems established for the detection of infections and prompt and appropriate preventive measures following the identification of positive individuals will help prevent further cluster infections.
Subject(s)
COVID-19 , Coronavirus Infections , HypoventilationABSTRACT
This is a case report on a cluster infection of novel severe acute respiratory syndrome coronavirus 2 delta AY.1 variant at an accommodation facility and the subsequent attempts to isolate individuals who tested positive. The background that facilitated this cluster was investigated, and the conditions in which infection was established, the infection route, and the effectiveness of routine measures were evaluated. Ninety-nine staff members had been working at the accommodation facility at the time of infection, and it was estimated that 10 members were infected with the delta AY.1 variant. Our results suggest that infection of staff from a patient staying overnight should be excluded. The factors contributing to the cluster infection involved short-distance conversations with individuals wearing non-woven three-layer masks moved out of position (non-woven) and gathering together with individuals wearing non-woven masks in hypoventilated conditions. Our findings also indicate that this variant is possibly airborne and can infect individuals in enclosed spaces with poor ventilation, even when either infected or exposed individuals wear non-woven masks. The routine maintenance of systems established for the detection of infections and prompt and appropriate preventive measures following the identification of positive individuals will help prevent further cluster infections.
Subject(s)
COVID-19 , Coronavirus Infections , HypoventilationABSTRACT
Background: The risk of SARS-CoV-2 infection when people handle the linens used by coronavirus disease (COVID-19) patients is uncertain. We examined the risk of SARS-CoV-2 infection among workers who change and wash the linens contaminated by SARS-CoV-2.Methods: This was a randomized controlled trial. Participants at a hospital and an accommodation facility who tested positive for SARS-CoV-2 were registered from September 16 to November 19, 2020. One of five washing (water, detergent, or softener) and disinfection (80℃ 10 min or 250 ppm sodium hypochlorite) methods was assigned to each facility on each washing day (the day of admission (day 1) and day 3) using static simple randomization. Samples before and after washing/disinfection were tested for RT-PCR and virus isolation on day 1 and day 3. The air in the workspace and the personal protective equipment worn by linen-handling people were also tested on days 1, 3, 5 and 7.Findings: Among 700 samples from 13 COVID-19 participants and their surrounding environment, SARS-CoV-2 RNA was detected from 14% (52/362) of the linens used by COVID-19 patients (cycle threshold (Ct) value:33-40). After washing or disinfection, SARS-CoV-2 RNA was detected from samples washed by laundry detergent or fabric softener with high Ct values (>36). SARS-CoV-2 RNA was also detected with high Ct values (>36) from 10% of gowns from people who handled used linens (5/52) but not from goggles nor N95 masks, and from 15% of air samples in the rooms where linens were retrieved (16/104). No SARS-CoV-2 was isolated from any samples.Interpretation: The risk of SARS-CoV-2 infection in handling linens used by COVID-19 patients exists but seems to be low and the contaminated linens were safe after washing by laundry detergent.Funding: This study was supported by the grant from Ministry of Health, Labour and Welfare (Grant No. 20CA2036).Declaration of Interest: All authors declare that they have no conflict of interest.Ethical Approval: This study was approved by the Institutional Review Boards of the National Institute of Infectious Diseases Japan (approval No. 1167) and International University of Health and Welfare (approval No. 20-Nr-066).
Subject(s)
COVID-19 , Coronavirus Infections , Communicable DiseasesABSTRACT
BackgroundAfter the first case of COVID-19 in Japan on 15 January 2020, multiple nationwide COVID-19 clusters were identified by the end of February. The Japanese government focused on mitigating emerging COVID-19 clusters by conducting active nationwide epidemiological surveillance. However, an increasing number of cases appeared until early April, many with unclear infection routes exhibiting no recent history of travel outside Japan. We aimed to evaluate the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) genome sequences from COVID-19 cases until early April and characterise the genealogical networks to demonstrate possible routes of spread in Japan. MethodsNasopharyngeal specimens were collected from patients and a quantitative reverse transcription polymerase chain reaction testing for SARS-CoV-2 was performed. Positive RNA samples were subjected whole genome sequencing and a haplotype network analysis was performed. FindingsSome of the primary clusters identified during January and February in Japan directly descended from Wuhan-Hu-1-related isolates in China and other distinct clusters. Clusters were almost contained until mid-March; the haplotype network analysis demonstrated that COVID-19 cases from late March through early April may have caused an additional large cluster related to the outbreak in Europe, leading to additional spread within Japan. National self-restraint during February was effective in mitigating the COVID-19 spread, but late action on stopping immigration and declaring national emergency in Japan might be involved in the later increase in cases. InterpretationGenome surveillance suggested that at least two distinct SARS-CoV-2 introductions from China and other countries occurred. FundingJapan Agency for Medical Research and Development.
Subject(s)
COVID-19ABSTRACT
Background A COVID-19 outbreak occurred in a cruise ship with 3711 passengers and crew in 2020. This study is to test the hypothesis that environmental surfaces played important roles in transmission for SARS-CoV-2 during this outbreak. Methods We sampled environmental surfaces including air from common areas in the cruise ship and cabins in which confirmed COVID-19 cases and non-cases had stayed after they left the cabins. We tested the samples for SARS-CoV-2 by rt-PCR and conducted viral isolation. Findings Of 601 samples tested, SARS-CoV-2 RNA was detected from 58 samples (10%) from case-cabins from which they left 1-17 days before sampling, but not from non-case-cabins. Except for one sample from an air hood in a corridor, SARS-CoV-2 RNA was not detected from samples in common areas. SARS-CoV-2 RNA was not detected from all 14 air samples. RNA was most often detected on the floor around toilet in the bathroom (39%, 13/33, cycle quantification (Cq): 26.21-37.62) and bed pillow (34%, 11/32, Cq: 34.61-38.99). There was no difference in the detection proportion between cabins for symptomatic (15%, 28/189, Cq: 29.79-38.86) and asymptomatic cases (21%, 28/131, Cq: 26.21-38.99). No SARS-CoV-2 virus was isolated from any of the samples. Interpretation The environment around the COVID-19 cases was extensively contaminated from SARS-CoV-2 during COVID-19 outbreak in the cruise ship. Transmission risk of SARS-CoV-2 from symptomatic and asymptomatic patients seems to be similar and the environmental surface could involve viral transmission through direct contact.
Subject(s)
COVID-19ABSTRACT
The Diamond Princess (DP) cruise ship was put under quarantine offshore Yokohama, Japan, after a passenger who disembarked in Hong Kong was confirmed as a COVID-19 case. We performed whole genome sequencing of SARS-CoV-2 directly from PCR-positive clinical specimens and conducted a haplotype network analysis of the outbreak. All tested isolates exhibited a transversion at G11083T, suggesting that SARS-CoV-2 dissemination on the DP originated from a single introduction event before the quarantine started. Although further spreading might have been prevented by quarantine, some progeny clusters were linked to transmission through mass-gathering events in the recreational areas and direct transmission among passengers who shared cabins during the quarantine. This study demonstrates the usefulness of haplotype network analysis in identifying potential infection routes.