Increased Secondary Attack Rates among the Household Contacts of Patients with the Omicron Variant of the Coronavirus Disease 2019 in Japan

Ogata, Tsuyoshi; Tanaka, Hideo; Tanaka, Emiko; Osaki, Natsumi; Noguchi, Etsuko; Osaki, Yukino; Tono, Ayane; Wada, Koji

doi:10.3390/ijerph19138068

Cited by 13 publications

(17 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We also observed, as other epidemiological studies have, 8,18,19,31-33 that infection with the Omicron variant was associated with increased transmission compared with ancestral viral variants. However, the use of rapid nasal-swab tests (as opposed to other test types) to detect index cases had a similar conditional direct effect on transmission to household contacts as infection with the Omicron variant.…”

Section: Discussionsupporting

confidence: 89%

“…Our results were also consistent with previous observations that infection with the Omicron variant is associated with greater transmission than ancestral variants. 8,18,19,31-33 Increased transmissibility of the Omicron variant compared to ancestral variants was observed in our study by both aOR (3.64, 95% CI 0.88–15.07), as well as aSAR stratified by whether the index case was infected with the Omicron variant (46.9%, 95% CI 32.3%-61.6%) or an ancestral variant (27.3%, 95% CI 17.7%-36.9%). Increased transmissibility of the Omicron variant was not observed in the univariable model ( Table S2 ), likely because this model does not correct for a compensating, protective effect of vaccination, which was more prevalent among individuals from households infected with the Omicron variant (76.7%) than ancestral variants (17.5%, Table S1 ).…”

Section: Resultsmentioning

confidence: 99%

“…The overall SAR (34.4%) we observed was similar to what others have reported. 5,12,18,31,65,66 Relatedly, in one of those studies 5 , household transmission was monitored by daily high-analytical-sensitivity screening testing and the SAR calculated using only nasal-swab test data was lower than when both saliva and nasal-swab test data were used, which supports that even high-analytical-sensitivity nasal-swab testing may miss some infected individuals, and that the specimen type used for evaluation can impact estimates of transmission.…”

Section: Discussionmentioning

confidence: 99%

“…14,18,[23][24][25] Lastly, SARS-CoV-2 variants such as Delta and Omicron have been shown in large studies to have greater transmissibility compared with ancestral variants. 8,18,19,[26][27][28][29][30][31][32][33] Early identification of an infectious individual is a critical step to reduce subsequent transmission, including within households. Because transmission of SARS-CoV-2 occurs during both the asymptomatic and symptomatic periods of infection, [34][35][36][37] diagnostic testing to quickly prompt infection control practices has been effective to limit additional exposures and transmission.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Index Cases First Identified by Nasal-Swab Rapid COVID-19 Tests Had More Transmission to Household Contacts Than Cases Identified by Other Test Types

Winnett

Shelby

et al. 2023

Preprint

View full text Add to dashboard Cite

Importance: At-home rapid COVID-19 tests utilize nasal-swab specimens and require high viral loads to reliably give positive results. Longitudinal studies from the onset of infection have found infectious virus can present in oral specimens days before nasal. Detection and initiation of infection-control practices may therefore be delayed when nasal-swab rapid tests are used, resulting in greater exposure and transmission to contacts. Objective: We assessed whether index cases first identified by rapid nasal-swab COVID-19 tests had more transmission to household contacts than index cases who used other test types (tests with higher analytical sensitivity but longer turnaround times, and/or that utilize non-nasal specimen types). Design: In this observational cohort study, members of households with a recent COVID-19 case were screened for infection at least daily by RT-qPCR on one or more self-collected upper-respiratory specimen types. Participants reported demographic/medical information (including COVID-19 testing), symptom and exposure information, and household infection-control practices. A two-level random intercept model was used to assess the association between the infection outcome of household contacts and each covariable (household size, race/ethnicity, age, vaccination status, viral variant, infection-control practices, and whether a rapid nasal-swab test was used to initially identify the household index case). Setting: Southern California, September 2020-June 2021 and November 2021-March 2022. Participants: Cohort of 370 individuals from 85 households. Main Outcome(s) and Measure(s): Transmission was quantified by adjusted secondary attack rates (aSAR) and adjusted odds ratios (aOR). Results: An aSAR of 53.6% (95%CI 38.8-68.3%) was observed among households where the index case first tested positive by a rapid nasal-swab COVID-19 test, which was significantly higher than the aSAR for households where the index case utilized another test type (27.2% [19.5-35.0%], P=0.003 pairwise comparisons of predictive margins). We observed an aOR of 4.90 (95%CI 1.65-14.56) for transmission to household contacts when a nasal-swab rapid test was used to identify the index case, compared to other test types. Conclusions and Relevance: Use of nasal-swab rapid COVID-19 tests for initial detection of infection and initiation of infection control may not limit transmission as well as other test types.

show abstract

Section: Discussionsupporting

confidence: 89%

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Index Cases First Identified by Nasal-Swab Rapid COVID-19 Tests Had More Transmission to Household Contacts Than Cases Identified by Other Test Types

Winnett

Shelby

et al. 2023

Preprint

View full text Add to dashboard Cite

show abstract

“…, unpub. data, https://www.medrxiv.org/content /10.1101/2021.12.27.21268278v1), Japan (25.2%)(12), Northern Spain (24%)(13), and those published in a systematic review and meta-analysis (22.5%) (14) but was similar to the 43.1% SAR reported in South Korea(15). For the Omicron variant, the SAR in our study was higher than those reported in Denmark (31%) (F.P.…”

mentioning

confidence: 99%

SARS-CoV-2 Secondary Attack Rates in Vaccinated and Unvaccinated Household Contacts during Replacement of Delta with Omicron Variant, Spain

López-Muñoz¹,

Torrella²,

López-Quílez³

et al. 2022

Emerg. Infect. Dis.

View full text Add to dashboard Cite

T he mass vaccination against SARS-CoV-2 that began at the end of 2020 reduced COVID-19-related mortality and severity in countries where substantial vaccine coverage was achieved (1,2). The vaccines also had a protective effect against the most recent variants (3,4). However, expectations that vaccines would stop community transmission of SARS-CoV-2 through herd immunity were quickly dampened by the early observation of infection and re-infection among vaccinated persons; waning vaccine effectiveness against transmission (VET) over time was observed (1,3) and confirmed in a large systematic literature review (5). Despite these results, protective effects of vaccination against infection among contacts have been reported (6). The vaccination status of index case-patients was also shown to play a role (6), underscoring the importance of vaccination for reducing the circulation of SARS-CoV-2. Nonetheless, the emergence of new variants of concern (VOC) with increased infectivity is an ongoing challenge for VET of currently licensed vaccines; early reports have shown a substantially lower VET for the Delta variant (B.1.617.2) compared with previous VOCs (7). Furthermore, rapid replacement of the Delta variant by Omicron (B.1.1.529) began in late 2021; the Omicron variant showed a transmission advantage because of its shorter generation time (S. Abbott et al., unpub. data, https://www.medrxiv.org/content/10.1101/2 022.01.08.22268920v1).Evaluating both variant virulence and SARS-CoV-2 VET under high vaccine coverage levels has major epidemiologic, social, and policy implications. We report the results of an observational study of household contacts of SARS-CoV-2-infected index case-patients during a Delta variant-dominant period from September to December 2021 and an Omicron variant-dominant period during January 2022 in a north-metropolitan area of Barcelona, Spain. We

show abstract

Nasal spray of an IgM‐like ACE2 fusion protein HH‐120 prevents SARS‐CoV‐2 infection: Two investigator‐initiated postexposure prophylaxis trials

Song,

Chen,

et al. 2023

Journal of Medical Virology

View full text Add to dashboard Cite

HH‐120, an IgM‐like angiotensin converting enzyme 2 (ACE2) fusion protein, has been developed as a nasal spray against Severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) and is currently undergoing human trials. HH‐120 nasal spray was assessed for postexposure prophylaxis (PEP) in two investigator‐initiated (NS01 and NS02) trials with different risk levels of SARS‐CoV‐2 exposure. NS01 enrolled family caregiver participants who had continuous contacts with laboratory‐confirmed index cases; NS02 enrolled participants who had general contacts (Part 1) or close contacts (Part 2) with index cases. The primary endpoints were safety and laboratory‐confirmed and/or symptomatic SARS‐CoV‐2 infection. In NS01 trial (14 participants), the SARS‐CoV‐2 infection rates were 25% in the HH‐120 group and 83.3% in the external control group (relative risk reduction [RRR]: 70.0%). In NS02‐Part 1 (193 participants), the infection rates were 4% (HH‐120) versus 11.3% (placebo), symptomatic infection rates were 0.8% versus 3.5%, hence with a RRR of 64.6% and 77.1%, respectively. In Part 2 (76 participants), the infection rates were 17.1% (HH‐120) versus 30.4% (placebo), symptomatic infection rates were 7.5% versus 27.3%, with a RRR of 43.8% and 72.5%, respectively. No HH‐120‐related serious adverse effects were observed. The HH‐120 nasal spray used as PEP was safe and effective in preventing laboratory‐confirmed and symptomatic SARS‐CoV‐2 infection.

show abstract

Increased Secondary Attack Rates among the Household Contacts of Patients with the Omicron Variant of the Coronavirus Disease 2019 in Japan

Cited by 13 publications

References 27 publications

Index Cases First Identified by Nasal-Swab Rapid COVID-19 Tests Had More Transmission to Household Contacts Than Cases Identified by Other Test Types

Index Cases First Identified by Nasal-Swab Rapid COVID-19 Tests Had More Transmission to Household Contacts Than Cases Identified by Other Test Types

SARS-CoV-2 Secondary Attack Rates in Vaccinated and Unvaccinated Household Contacts during Replacement of Delta with Omicron Variant, Spain

Nasal spray of an IgM‐like ACE2 fusion protein HH‐120 prevents SARS‐CoV‐2 infection: Two investigator‐initiated postexposure prophylaxis trials

Contact Info

Product

Resources

About