RESUMO
ObjectiveãWe examined the effectiveness of governmental declarations on the changing temporal trends in the incidence of COVID-19 cases with unknown transmission routes (unlinked cases) before SARS-CoV-2 vaccines became available in Osaka.MethodsãSeven-day moving averages of the incidence of unlinked COVID-19 cases were calculated using daily reports posted on the official website of the Osaka Prefectural Government for the third (October 10, 2020-February 28, 2021) and fourth COVID-19 waves and about one week before and after (February 23, 2021-June 27, 2021). Then, we calculated daily percentage changes and identified dates of significant change ("Joinpoint") with a Joinpoint regression analysis. The date of a major change in the behavior of prefectural residents associated with the risk of infection (the date of a sudden change in behavior) was defined as the date counting backward from each Joinpoint date and considering the incubation period and interval between the date of onset and disclosure of the daily report. Subsequently, we examined the temporal relationships between the declaration date and defined date of the sudden change in behavior associated with the risk of infection.ResultsãFive Joinpoint dates contributing to a significant downward trend were identified: November 23, 2020, and in 2021, January 7, January 18, April 12, and April 30. We defined dates of sudden changes in behavior from each Joinpoint date from the corresponding time lag (8 to 9.9 days): in 2020, November 13 and December 30; in 2021, January 9, April 4, and April 22. Regarding the five estimated dates, the second emergency declaration was issued on January 9, 2021. Further, the first introduction of priority preventive measures was given on April 4, 2021. April 22 fell between the date that the third emergency declaration was requested and the date of its issuance.ConclusionãThese descriptive epidemiological findings suggest that the issuance of these declarations could be triggers that reinforced infection avoidance behavior among Osaka prefectural residents, which resulted in the downward trends in unlinked COVID-19 cases.
Assuntos
COVID-19 , Humanos , COVID-19/epidemiologia , SARS-CoV-2 , Vacinas contra COVID-19 , IncidênciaRESUMO
ObjectivesãThere is little evidence supporting the transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from presymptomatic or asymptomatic SARS-CoV-2-infected individuals in Japan, where the incidence of SARS-CoV-2 infection is lower than that in other developed countries. This study aimed to determine whether SARS-CoV-2 transmission can occur from presymptomatic or asymptomatic SARS-CoV-2-infected individuals.MethodsãWe surveyed all directors of Japanese public health centers for index cases and secondary patients who possibly contracted SARS-CoV-2 infection from a presymptomatic or asymptomatic SARS-CoV-2-infected individual who came under their care before June 20, 2020. The professional staff at the centers routinely perform contact tracing of infected persons based on the guidelines of the Infection Control Act. Four authors independently reviewed reports of 9 index cases of SARS-CoV-2-infected individuals with 17 secondary patients from 8 prefectures and examined the cases to determine whether transmission from a SARS-CoV-2-infected individual in the presymptomatic or asymptomatic state occurred.ResultsãWe reported 7 index cases with 13 secondary patients. 1) An elderly woman acquired SARS-CoV-2 infection from her sustained asymptomatic granddaughter at home, 2) 4 guests and 1 accompanying child waiting at a hair salon acquired infection from the presymptomatic female hair stylist, 3) 2 inpatients acquired infection from a presymptomatic nurse while providing nursing care in close contact, 4) an elderly couple acquired SARS-CoV-2 infection from their presymptomatic relative who was in the 50s during household care at their home, 5) a man acquired SARS-CoV-2 infection from a presymptomatic adult neighbor in an enclosed space with poor ventilation, 6) a presymptomatic man had transmitted infection to another man at a coffee shop while having a discussion on business, and 7) a man in his 50s acquired SARS-CoV-2 infection from a presymptomatic man during 50 minutes of close contact at their office and in a car. These secondary patients had no other likely routes of infection. The interval between the date of symptom onset in the presymptomatic index case and the secondary patient ranged from 2 to 6 days. The incidence rates at the time these infections occurred in the corresponding prefectures ranged from 0.00 to 6.56 cases/1 million person-days.ConclusionãWe report the first case of SARS-CoV-2 transmission from a sustained asymptomatic index case in Japan. All secondary patients came into close contact with presymptomatic index cases in areas with poor ventilation.
Assuntos
Doenças Assintomáticas/epidemiologia , COVID-19/epidemiologia , COVID-19/transmissão , Portador Sadio/epidemiologia , Portador Sadio/transmissão , Busca de Comunicante , SARS-CoV-2 , Adulto , Idoso , Feminino , Humanos , Período de Incubação de Doenças Infecciosas , Japão/epidemiologia , Masculino , Pessoa de Meia-Idade , Adulto JovemRESUMO
Severe fever with thrombocytopenia syndrome (SFTS) is a novel tick-borne infectious disease, therefore, the information on the whole genome of the SFTS virus (SFTSV) is still limited. This study demonstrates a nearly whole genome of the SFTSV identified in Osaka in 2017 and 2018 by next-generation sequencing (NGS). The evolutionary lineage of two genotypes, C5 and J1, was identified in Osaka. The first case in Osaka belongs to suspect reassortment (L:C5, M:C5, S:C4), the other is genotype J1 (L: J1, M: J1, S: J1) according to the classification by a Japanese group. C5 was identified in China, indicating that C5 identified in this study may be transmitted by birds between China and Japan. This study revealed that different SFTSV genotypes were distributed in two local areas, suggesting the separate or focal transmission patterns in Osaka.