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1.
Jpn J Infect Dis ; 2021 Oct 29.
Article in English | MEDLINE | ID: covidwho-1865648

ABSTRACT

Characteristics of COVID-19 clusters in medical and social welfare facilities, and factors associated with cluster size are still not fully understood. We reviewed COVID-19 cases identified from January 15 to April 30 of 2020 in Japan, and analyzed factors associated with cluster size in medical and social welfare facilities. In the study, COVID-19 clusters were identified in 56 medical and 34 social welfare facilities. Numbers of cases in those facilities reached their peaks after the peak of general population. Duration of occurrence of new cases in clusters showed a positive correlation with the number of cases in both types of facilities (rho = 0.44, p < 0.001; and rho = 0.69, p < 0.001, respectively). However, number of days between the first case in the prefecture and the onset of clusters showed a negative correlation with the number of cases only in clusters in social welfare facilities (rho = -0.4, p = 0.004). Our results suggested that COVID-19 cases in those facilities were prevalent in the latter phase of the community transmissions, although the underlying mechanisms for such trend could be different between medical and social welfare facilities.

2.
Western Pac Surveill Response J ; 13(1): 1-6, 2022.
Article in English | MEDLINE | ID: covidwho-1856104

ABSTRACT

In response to the outbreak of coronavirus disease 2019 (COVID-19) in Japan, a national COVID-19 cluster taskforce (comprising governmental and nongovernmental experts) was established to support the country's Ministry of Health, Labour and Welfare in conducting daily risk assessment. The assessment was carried out using established infectious disease surveillance systems; however, in the initial stages of the pandemic these were not sufficient for real-time risk assessment owing to limited accessibility, delay in data entry and inadequate case information. Also, local governments were publishing anonymized data on confirmed COVID-19 cases on their official web sites as daily press releases. We developed a unique database for nationwide real-time risk assessment that included these case lists from local government web sites and integrated all case data into a standardized format. The database was updated daily and checked systematically to ensure comprehensiveness and quality. Between 15 January 2020 and 15 June 2021, 776 459 cases were logged in the database, allowing for analysis of real-time risk from the pandemic. This semi-automated database was used in daily risk assessments, and to evaluate and update control measures to prevent community transmission of COVID-19 in Japan. The data were reported almost every week to the Japanese Government Advisory Panel on COVID-19 for public health responses.


Subject(s)
COVID-19 , COVID-19/epidemiology , Humans , Japan/epidemiology , Pandemics , Public Health , Risk Assessment
3.
SSM Popul Health ; 18: 101114, 2022 Jun.
Article in English | MEDLINE | ID: covidwho-1852100

ABSTRACT

Immigrants in Japan face multiple health care challenges. There is limited research addressing how all-cause mortality differs between foreign residents and Japanese citizens, including the impact of the COVID-19 pandemic. We assessed whether all-cause mortality rates between Japanese citizens and foreign residents living in Japan differ, and whether these differentials changed after the start of the COVID-19 pandemic. We conducted a cross-sectional analysis using vital statistical data of all deaths among citizens and foreign residents that occurred within Japanese borders aggregated every 6 months between January 1, 2015 and June 30, 2021. Data were used to calculate sex-, region-, and 20-year age group-specific standardized mortality rates using the direct method based on the population distribution of Japanese citizens in 2021 by sex, region, and 20-year age groups. Chi-squared tests and linear regression were used to assess whether the pandemic was associated with changes in mortality rates among groups and changes in the mortality differentials between citizens and non-citizens, respectively. All-cause mortality increased monotonically with age for men and women. Men had higher mortality than women, regardless of age or nationality. All-cause mortality is lower among immigrants than Japanese citizens between the ages of 20-59, but higher under the age of 20 and over the age of 59. The pandemic was associated with significant changes in mortality in most groups, but no statistically significant changes in the mortality differentials between immigrants and Japanese citizens were detected. Young immigrants are generally healthier than their Japanese counterparts, in line with the healthy migrant hypothesis. Younger migrants are at higher risk of mortality, possibly due to increased vulnerability to psychologic stress. Older migrant mortality converged with citizen mortality, consistent with acculturation that occurs with longer duration of residence. The pandemic did not exacerbate health inequities for foreign residents with respect to mortality.

4.
Western Pac Surveill Response J ; 13(1): 1-5, 2022.
Article in English | MEDLINE | ID: covidwho-1835497

ABSTRACT

Objective: Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), was first reported in China and subsequently spread worldwide. In Japan, many clusters occurred during the first wave in 2020. We describe the investigation of an early outbreak in a Tokyo hospital. Methods: A COVID-19 outbreak occurred in two wards of the hospital from April to early May 2020. Confirmed cases were individuals with laboratory-confirmed SARS-CoV-2 infection linked to Wards A and B, and contacts were patients or workers in Wards A or B 2 weeks before the index cases developed symptoms. All contacts were tested, and cases were interviewed to determine the likely route of infection and inform the development of countermeasures to curb transmission. Results: There were 518 contacts, comprising 472 health-care workers (HCWs) and 46 patients, of whom 517 were tested. SARS-CoV-2 infection was confirmed in 42 individuals (30 HCWs and 12 patients). The proportions of SARS-CoV-2 infections in HCWs were highest among surgeons, nurses, nursing assistants and medical assistants. Several HCWs in these groups reported being in close proximity to one another while not wearing medical masks. Among HCWs, infection was thought to be associated with the use of a small break room and conference room. Discussion: Nosocomial SARS-CoV-2 infections occurred in two wards of a Tokyo hospital, affecting HCWs and patients. Not wearing masks was considered a key risk factor for infection during this outbreak; masks are now a mandated countermeasure to prevent the spread of SARS-CoV-2 infection in hospital settings.


Subject(s)
COVID-19 , Cross Infection , COVID-19/epidemiology , COVID-19/prevention & control , Cross Infection/epidemiology , Cross Infection/prevention & control , Disease Outbreaks/prevention & control , Hospitals , Humans , Japan/epidemiology , Pandemics/prevention & control , Patients' Rooms , SARS-CoV-2 , Tokyo/epidemiology
5.
Open Forum Infect Dis ; 9(5): ofac158, 2022 May.
Article in English | MEDLINE | ID: covidwho-1831309

ABSTRACT

Background: Singing in an indoor space may increase the risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. We conducted a case-control study of karaoke-related coronavirus disease 2019 (COVID-19) outbreaks to reveal the risk factors for SARS-CoV-2 infection among individuals who participate in karaoke. Methods: Cases were defined as people who enjoyed karaoke at a bar and who tested positive for SARS-CoV-2 by reverse-transcription polymerase chain reaction between 16 May and 3 July 2020. Controls were defined as people who enjoyed karaoke at the same bar during the same period as the cases and tested negative. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated. ORs of key variables adjusted for each other were also estimated (aOR). Results: We identified 81 cases, the majority of whom were active elderly individuals (median age, 75 years). Six cases died (case fatality ratio, 7%). Among the cases, 68 (84%) were guests, 18 of whom had visited ≧2 karaoke bars. A genome analysis conducted in 30 cases showed 6 types of isolates within 4 single-nucleotide variation difference. The case-control study revealed that singing (aOR, 11.0 [95% CI, 1.2-101.0]), not wearing a mask (aOR, 3.7 [95% CI, 1.2-11.2]), and additional hour spent per visit (aOR, 1.7 [95% CI, 1.1-2.7]) were associated with COVID-19 infection. Conclusions: A karaoke-related COVID-19 outbreak that occurred in 2 different cities was confirmed by the results of genome analysis. Singing in less-ventilated, indoor and crowded environments increases the risk of acquiring SARS-CoV-2 infection. Wearing a mask and staying for only a short time can reduce the risk of infection during karaoke.

6.
Western Pacific Surveillance and Response Journal : WPSAR ; 13(1):1-5, 2022.
Article in English | EuropePMC | ID: covidwho-1812988

ABSTRACT

Objective Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), was first reported in China and subsequently spread worldwide. In Japan, many clusters occurred during the first wave in 2020. We describe the investigation of an early outbreak in a Tokyo hospital. Methods A COVID-19 outbreak occurred in two wards of the hospital from April to early May 2020. Confirmed cases were individuals with laboratory-confirmed SARS-CoV-2 infection linked to Wards A and B, and contacts were patients or workers in Wards A or B 2 weeks before the index cases developed symptoms. All contacts were tested, and cases were interviewed to determine the likely route of infection and inform the development of countermeasures to curb transmission. Results There were 518 contacts, comprising 472 health-care workers (HCWs) and 46 patients, of whom 517 were tested. SARS-CoV-2 infection was confirmed in 42 individuals (30 HCWs and 12 patients). The proportions of SARS-CoV-2 infections in HCWs were highest among surgeons, nurses, nursing assistants and medical assistants. Several HCWs in these groups reported being in close proximity to one another while not wearing medical masks. Among HCWs, infection was thought to be associated with the use of a small break room and conference room. Discussion Nosocomial SARS-CoV-2 infections occurred in two wards of a Tokyo hospital, affecting HCWs and patients. Not wearing masks was considered a key risk factor for infection during this outbreak;masks are now a mandated countermeasure to prevent the spread of SARS-CoV-2 infection in hospital settings.

7.
Western Pacific Surveillance and Response Journal : WPSAR ; 13(1):1-6, 2022.
Article in English | EuropePMC | ID: covidwho-1812914

ABSTRACT

In response to the outbreak of coronavirus disease 2019 (COVID-19) in Japan, a national COVID-19 cluster taskforce (comprising governmental and nongovernmental experts) was established to support the country’s Ministry of Health, Labour and Welfare in conducting daily risk assessment. The assessment was carried out using established infectious disease surveillance systems;however, in the initial stages of the pandemic these were not sufficient for real-time risk assessment owing to limited accessibility, delay in data entry and inadequate case information. Also, local governments were publishing anonymized data on confirmed COVID-19 cases on their official web sites as daily press releases. We developed a unique database for nationwide real-time risk assessment that included these case lists from local government web sites and integrated all case data into a standardized format. The database was updated daily and checked systematically to ensure comprehensiveness and quality. Between 15 January 2020 and 15 June 2021, 776 459 cases were logged in the database, allowing for analysis of real-time risk from the pandemic. This semi-automated database was used in daily risk assessments, and to evaluate and update control measures to prevent community transmission of COVID-19 in Japan. The data were reported almost every week to the Japanese Government Advisory Panel on COVID-19 for public health responses.

8.
BMC Infect Dis ; 22(1): 411, 2022 Apr 28.
Article in English | MEDLINE | ID: covidwho-1813294

ABSTRACT

BACKGROUND: The prevalence of virus positivity in the upper respiratory tract of asymptomatic community-dwelling older people remains elusive. Our objective was to investigate the prevalence of respiratory virus PCR positivity in asymptomatic community-dwelling older people using saliva samples and nasopharyngeal and oropharyngeal swabs. METHODS: We analyzed 504 community-dwelling adults aged ≥ 65 years who were ambulatory and enrolled in a cross-sectional study conducted from February to December 2018 in Nagasaki city, Japan. Fourteen respiratory viruses were identified in saliva, nasopharyngeal and oropharyngeal samples using multiplex PCR assays. RESULTS: The prevalences of PCR positivity for rhinovirus, influenza A, enterovirus and any respiratory virus were 12.9% (95% CI: 10.1-16.1%), 7.1% (95% CI: 5.1-9.8%), 6.9% (95% CI: 4.9-9.5%) and 25.2% (95% CI: 21.5-29.2%), respectively. Rhinovirus was detected in 21.5% of subjects, influenza A in 38.9% of subjects, enterovirus in 51.4% of subjects and any virus in 32.3% of subjects using only saliva sampling. CONCLUSIONS: The prevalences of several respiratory viruses were higher than the percentages reported previously in pharyngeal samples from younger adults. Saliva sampling is a potentially useful method for respiratory virus detection in asymptomatic populations.


Subject(s)
Enterovirus Infections , Influenza, Human , Respiratory Tract Infections , Viruses , Adult , Aged , Cross-Sectional Studies , Humans , Independent Living , Influenza, Human/epidemiology , Multiplex Polymerase Chain Reaction/methods , Nasopharynx , Respiratory Tract Infections/diagnosis , Respiratory Tract Infections/epidemiology , Rhinovirus , Viruses/genetics
9.
Influenza Other Respir Viruses ; 2022 Apr 26.
Article in English | MEDLINE | ID: covidwho-1807133

ABSTRACT

BACKGROUND: The relative burden of COVID-19 has been less severe in Japan. One reason for this may be the uniquely strict restrictions imposed upon bars/restaurants. To assess if this approach was appropriately targeting high-risk individuals, we examined behavioral factors associated with SARS-CoV-2 infection in the community. METHODS: This multicenter case-control study involved individuals receiving SARS-CoV-2 testing in June-August 2021. Behavioral exposures in the past 2 weeks were collected via questionnaire. SARS-CoV-2 PCR-positive individuals were cases, while PCR-negative individuals were controls. RESULTS: The analysis included 778 individuals (266 [34.2%] positives; median age [interquartile range] 33 [27-43] years). Attending three or more social gatherings was associated with SARS-CoV-2 infection (adjusted odds ratio [aOR] 2.00 [95% CI 1.31-3.05]). Attending gatherings with alcohol (aOR 2.29 [1.53-3.42]), at bars/restaurants (aOR 1.55 [1.04-2.30]), outdoors/at parks (aOR 2.87 [1.01-8.13]), at night (aOR 2.07 [1.40-3.04]), five or more people (aOR 1.81 [1.00-3.30]), 2 hours or longer (aOR 1.76 [1.14-2.71]), not wearing a mask during gatherings (aOR 4.18 [2.29-7.64]), and cloth mask use (aOR 1.77 [1.11-2.83]) were associated with infection. Going to karaoke (aOR 2.53 [1.25-5.09]) and to a gym (aOR 1.87 [1.11-3.16]) were also associated with infection. Factors not associated with infection included visiting a cafe with others, ordering takeout, using food delivery services, eating out by oneself, and work/school/travel-related exposures including teleworking. CONCLUSIONS: We identified multiple behavioral factors associated with SARS-CoV-2 infection, many of which were in line with the policy/risk communication implemented in Japan. Rapid assessment of risk factors can inform decision making.

10.
EuropePMC; 2022.
Preprint in English | EuropePMC | ID: ppcovidwho-334295

ABSTRACT

Backgrounds: This study analysed secondary attack rates (SARs), comparing alpha variants, delta variants and non-variants of concern (non-VOCs), using clinical and close-contact tracing data.MethodsWe analysed coronavirus disease 2019 (COVID-19) case data from a database and contact tracing data between July and October 2020 (Cohort 1) and April 2021 (Cohort 2) and between July and August 2021 (Cohort 3) in a city in Toyama prefecture, Japan. Real-time polymerase chain reaction (PCR) was used to detect the N501Y (alpha variant) and L452R (delta variant) mutations. We calculated the SARs considering close contact, index case and contact setting characteristics. Relative risks (RRs) of secondary attack were analysed using Poisson regression models.ResultsAmong 123 index cases and 530 close contacts in Cohort 1, 246 index cases and 988 close contacts in Cohort 2, and 304 index cases and 984 close contacts in Cohort 3, the SARs associated with alpha and delta variant index cases were 1.47 times and 1.89 times higher than those associated with non-VOC index cases. Delta variant index cases were associated with the highest SAR (29.2%) in the same household and a 2.40-fold (95% CI: 1.62-3.56) higher risk of transmission than non-VOC index cases. The age and symptoms of index cases were associated with the SAR.ConclusionsWe confirmed that VOC index cases were associated with increased transmissibility. Population longitudinal surveillance data linked with contact-tracing data provide valuable information for elucidation of the characteristics of newly emerging variants.

11.
Clin Infect Dis ; 2022 Apr 19.
Article in English | MEDLINE | ID: covidwho-1795351

ABSTRACT

BACKGROUND: Although high vaccine effectiveness of messenger RNA (mRNA) coronavirus disease 2019 (COVID-19) vaccines was reported in studies in several countries, data is limited from Asian countries, especially against the Delta (B.1.617.2) variant. METHODS: We conducted a multicenter test-negative case-control study in patients aged 16 visiting hospitals or clinics with signs or symptoms consistent with COVID-19 from July 1 to September 30, 2021, when the Delta variant was dominant (90% of severe acute respiratory syndrome coronavirus 2 [SARS-CoV-2] infections) nationwide in Japan. Vaccine effectiveness of BNT162b2 or mRNA-1273 against symptomatic SARS-CoV-2 infections was evaluated. Waning immunity among patients aged 16 to 64 was also assessed. RESULTS: We enrolled 1936 patients, including 396 test-positive cases and 1540 test-negative controls for SARS-CoV-2. The median age was 49 years, 53.4% were male, and 34.0% had underlying medical conditions. Full vaccination (receiving two doses 14 days before symptom onset) was received by 6.6% of cases and 38.8% of controls. Vaccine effectiveness of full vaccination against symptomatic SARS-CoV-2 infections was 88.7% (95% confidence interval [CI], 78.8-93.9) among patients aged 16 to 64 and 90.3% (95% CI, 73.6-96.4) among patients aged 65. Among patients aged 16 to 64, vaccine effectiveness within one to three months after full vaccination was 91.8% (95% CI, 80.3-96.6), and was 86.4% (95% CI, 56.9-95.7) within four to six months. CONCLUSIONS: mRNA COVID-19 vaccines had high effectiveness against symptomatic SARS-CoV-2 infections in Japan during July 1 to September 30, 2021, when the Delta variant was dominant nationwide.

12.
Open forum infectious diseases ; 2022.
Article in English | EuropePMC | ID: covidwho-1787333

ABSTRACT

Background Singing in an indoor space may increase the risk of SARS-CoV-2 infection. We conducted a case-control study of karaoke-related COVID-19 outbreaks to reveal the risk factors for SARS-CoV-2 infection among individuals who participate in karaoke. Methods Cases were defined as people who enjoyed karaoke at a bar and who tested positive for SARS-CoV-2 by RT-PCR between May 16 and July 3, 2020. Controls were defined as people who enjoyed karaoke at the same bar during the same period as the cases and tested negative. Odds ratio (OR) and confidence interval (CI) were calculated. ORs were adjusted by variables with significantly high odds ratio (aOR). Results We identified 81 cases, the majority of whom were active elderly individuals (median age: 75 years). Six cases died (case fatality ratio: 7%). Among the cases, 68 (84%) were guests, 18 of whom had visited more than two karaoke bars. A genome analysis conducted in 30 cases showed six types of isolates within four single-nucleotide variations difference. The case-control study revealed that singing (aOR 11.0, 95% CI, 1.2-101.0), not wearing a mask (aOR 3.7, 95% CI 1.2-11.2) and time spent per visit (aOR 1.7, 95% CI 1.1-2.7) were associated with COVID-19 infection. Conclusions A karaoke-related COVID-19 outbreak that occurred in two different cities was confirmed by the results of genome analysis. Singing in less-ventilated, indoor and crowded environments increases the risk of acquiring SARS-CoV-2 infection. Wearing a mask and staying for only a short time can reduce the risk of infection during karaoke.

13.
Jpn J Infect Dis ; 75(2): 192-194, 2022 Mar 24.
Article in English | MEDLINE | ID: covidwho-1761195

ABSTRACT

An outbreak of coronavirus 2019 (COVID-19) occurred in Ueda City, Nagano prefecture, Japan, which has a population of 150,000. The residents were a population naïve to COVID-19, and many of them had only one chance of exposure, in which careful epidemiological investigation could reveal attack rates among close contact on the specific date of exposure. We identified 89 cases and 328 close contacts. Among the close contacts, 114 had only one chance of exposure to the 20 index cases. During the follow-up period, 17 close contacts tested positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), overall attack rate of 15%, after the exposure to 6 infectors. The median number of close contacts for the 6 infectors was 5.5 (range 2-14). Attack rates among these close contacts were 13% (1/8), 20% (2/5), 33% (2/6), 50% (1/2), 64% (4/9 and 5/5), and 100% (2/2), respectively. The transmission risk of SARS-CoV-2 appears to peak one day before symptom onset, and is at similar levels two days before (16%) and on the day (20%) of symptom onset. A multidisciplinary approach is needed to control the COVID-19 outbreak, in addition to investigation, which began after case identification.


Subject(s)
COVID-19 , SARS-CoV-2 , COVID-19/epidemiology , Disease Outbreaks , Humans , Incidence , Japan/epidemiology
15.
Front Public Health ; 10: 775486, 2022.
Article in English | MEDLINE | ID: covidwho-1715077

ABSTRACT

Two-sided messages that include two perspectives (i.e., risks and benefits) are more effective than one-sided messages that convey only one perspective (usually only the benefits). Refutational two-sided messages are effective for communicating risks regarding vaccines. To examine the effectiveness of refutational two-sided messages in risk communication regarding novel vaccines against emerging infectious diseases, we conducted the randomized controlled study based on a 3 × 3 × 2 mixed design (Intervention 1: vaccines against subcutaneous influenza, "novel severe infectious disease," or intranasal influenza; intervention 2: one-sided, non-refutational two-sided, or refutational two-sided messages; two questionnaires) using a Japanese online panel. Participants completed questionnaires before and after receiving an attack message (negative information). We evaluated the impact of attack messages on the willingness to be vaccinated, and the anticipated regret of inaction (ARI). Among 1,184 participants, there was a significant difference in the willingness to be vaccinated among the message groups (p < 0.01). After receiving the attack message, willingness to be vaccinated decreased in the one-sided message group and increased in the non-refutational two-sided and refutational two-sided message groups. Additionally, ARI in the refutational two-sided message groups was significantly higher than in the one-sided groups (p = 0.03). In conclusion, two-sided messages are more effective than one-sided messages in terms of willingness to be vaccinated. Furthermore, the high ARI in the refutational two-sided message group indicated that refutational two-sided messages were more effective than one-sided messages for communicating the risks of vaccines, especially those against emerging infectious diseases.


Subject(s)
COVID-19 , Communicable Diseases, Emerging , Influenza Vaccines , Attitude , COVID-19/prevention & control , Communicable Diseases, Emerging/prevention & control , Humans , Pandemics , SARS-CoV-2
16.
EuropePMC; 2021.
Preprint in English | EuropePMC | ID: ppcovidwho-305709

ABSTRACT

Since little is known about viral and host characteristics of breakthrough infections after COVID-19 vaccination, a nationwide investigation of breakthrough cases was initiated in Japan. 130 cases (90%+ received mRNA vaccines) were reported with respiratory specimens in 117 cases and sera in 68 cases. A subset of cases shed infectious virus regardless of symptom presence or viral lineages. Viral lineages for breakthrough infections matched both temporally and spatially with the circulating lineages in Japan with no novel mutations in spike receptor binding domain that may have escaped from vaccine-induced immunity were found. Anti-spike/neutralizing antibodies of breakthrough infections in the acute phase owing to vaccine-induced immunity were significantly higher than those from unvaccinated convalescent individuals but were comparable to vaccinated uninfected individuals, and followed by boosting in the convalescent phase. Symptomatic cases had low anti-spike/neutralizing antibodies in the acute phase with robust boosting in the convalescent phase, suggesting the presence of serological correlate for symptom development in COVID-19 vaccine breakthrough infections.

17.
Int J Infect Dis ; 116: 365-373, 2022 Mar.
Article in English | MEDLINE | ID: covidwho-1641323

ABSTRACT

OBJECTIVES: Super-spreading events caused by overdispersed secondary transmission are crucial in the transmission of COVID-19. However, the exact level of overdispersion, demographics, and other factors associated with secondary transmission remain elusive. In this study, we aimed to elucidate the frequency and patterns of secondary transmission of SARS-CoV-2 in Japan. METHODS: We analyzed 16,471 cases between January 2020 and August 2020. We generated the number of secondary cases distribution and estimated the dispersion parameter (k) by fitting the negative binomial distribution in each phase. The frequencies of the secondary transmission were compared by demographic and clinical characteristics, calculating the odds ratio using logistic regression models. RESULTS: We observed that 76.7% of the primary cases did not generate secondary cases with an estimated dispersion parameter k of 0.23. The demographic patterns of primary-secondary cases differed between phases, with 20-69 years being the predominant age group. There were higher proportions of secondary transmissions among older individuals, symptomatic patients, and patients with 2 days or more between onset and confirmation. CONCLUSIONS: The study showed the estimation of the frequency of secondary transmission of SARS-CoV-2 and the characteristics of people who generated the secondary transmission.


Subject(s)
COVID-19 , SARS-CoV-2 , COVID-19/epidemiology , Demography , Humans , Japan/epidemiology
18.
Int J Infect Dis ; 115: 109-115, 2022 Feb.
Article in English | MEDLINE | ID: covidwho-1560960

ABSTRACT

BACKGROUND: Following an outbreak of coronavirus disease 2019 (COVID-19) on the cruise ship Diamond Princess, passengers and crew were followed-up to determine prognosis. This study examined the epidemiological determinants of COVID-19 natural history using these follow-up data. METHODS: Infection status, diagnosis, clinical symptoms and prognosis were analysed for all passengers and crew members on the Diamond Princess. In addition, the risk of infection associated with exposure within cabin rooms, as well as the risks of various clinical manifestations of disease, along with their epidemiological determinants, were analysed. RESULTS: The adjusted odds ratio (aOR) of infection for individuals tested by polymerase chain reaction on or after 12 February 2020 compared with individuals tested before this date was 0.53 [95% confidence interval (CI) 0.39-0.72], reflecting decreased transmission during onboard quarantine. Among infected individuals, older age was associated with elevated odds of symptomatic illness (aOR 1.01, 95% CI 1.00-1.02), severe disease (aOR 1.08, 95% CI 1.05-1.12) and death (aOR 1.12, 95% CI 1.05-1.21). CONCLUSIONS: Severe COVID-19 disease, death and symptomatic illness were more frequent among older individuals on the Diamond Princess. Older elderly cases (age ≥80 years) had the highest risks of severe disease and death. Inter-room transmission was prevented successfully by the onboard quarantine.


Subject(s)
COVID-19 , SARS-CoV-2 , Aged , Aged, 80 and over , Disease Outbreaks , Humans , Quarantine , Ships
19.
Nihon Naika Gakkai Zasshi ; 109(11):2270-2275, 2020.
Article in Japanese | J-STAGE | ID: covidwho-1511916
20.
Int J Epidemiol ; 51(1): 75-84, 2022 02 18.
Article in English | MEDLINE | ID: covidwho-1493814

ABSTRACT

BACKGROUND: Coronavirus disease 2019 (COVID-19) continues to be a major global health burden. This study aims to estimate the all-cause excess mortality occurring in the COVID-19 outbreak in Japan, 2020, by sex and age group. METHODS: Daily time series of mortality for the period January 2015-December 2020 in all 47 prefectures of Japan were obtained from the Ministry of Health, Labour and Welfare, Japan. A two-stage interrupted time-series design was used to calculate excess mortality. In the first stage, we estimated excess mortality by prefecture using quasi-Poisson regression models in combination with distributed lag non-linear models, adjusting for seasonal and long-term variations, weather conditions and influenza activity. In the second stage, we used a random-effects multivariate meta-analysis to synthesize prefecture-specific estimates at the nationwide level. RESULTS: In 2020, we estimated an all-cause excess mortality of -20 982 deaths [95% empirical confidence intervals (eCI): -38 367 to -5472] in Japan, which corresponded to a percentage excess of -1.7% (95% eCI: -3.1 to -0.5) relative to the expected value. Reduced deaths were observed for both sexes and in all age groups except those aged <60 and 70-79 years. CONCLUSIONS: All-cause mortality during the COVID-19 outbreak in Japan in 2020 was decreased compared with a historical baseline. Further evaluation of cause-specific excess mortality is warranted.


Subject(s)
COVID-19 , Disease Outbreaks , Female , Humans , Interrupted Time Series Analysis , Japan/epidemiology , Male , Mortality , SARS-CoV-2
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