scholarly journals Comparative Household Secondary Attack Rates associated with B.1.1.7, B.1.351, and P.1 SARS-CoV-2 Variants

2021 ◽  
Author(s):  
Kevin A Brown ◽  
Semra Tibebu ◽  
Nick Daneman ◽  
Kevin L Schwartz ◽  
Michael Whelan ◽  
...  
Keyword(s):  
Symptom Onset ◽  
Attack Rate ◽  
Surveillance System ◽  
Disease Surveillance ◽  
Index Case ◽  
Wild Type ◽  
Vaccination Rates ◽  
Household Contacts ◽  
Disease Surveillance System ◽  
Index Cases

Background: The emergence of SARS-CoV-2 variants associated with increased transmissibility are driving a 3rd global surge in COVID-19 incidence. There are currently few reliable estimates for the P.1 and B.1.351 lineages. We sought to compare the secondary attack rates of SARS-COV-2 mutations and variants in Canada's largest province of Ontario, using a previously validated household-based approach. Methods: We identified individuals with confirmed SARS-CoV-2 infection in Ontario's provincial reportable disease surveillance system. Cases were grouped into households based on reported residential address. Index cases had the earliest of symptom onset in the household. Household secondary attack rate was defined as the percentage of household contacts identified as secondary cases within 1-14 days after the index case. Results: We identified 26,888 index household cases during the study period. Among these, 7,555 (28%) were wild-type, 17,058 (63%) were B.1.1.7, 1674 (6%) were B.1.351 or P.1, and 601 (2%) were non-VOC mutants (Table 1). The secondary attack rates, according to index case variant were as follows: 20.2% (wild-type), 25.1% (B.1.1.7), 27.2% (B.1.351 or P.1), and 23.3% (non-VOC mutants). In adjusted analyses, we found that B.1.1.7, B.1.351, and P.1 index cases had the highest transmissibility (presumptive B.1.1.7 OR adjusted=1.49, 95%CI 1.36, 1.64; presumptive B.1.351 or P.1 OR adjusted=1.60, 95%CI 1.37, 1.87). Discussion: Substantially higher transmissibility associated with variants will make control of SARS-CoV-2 more difficult, reinforcing the urgent need to increase vaccination rates globally.

scholarly journals Household secondary attack rate of COVID-19 by household size and index case characteristics

2021 ◽  
Author(s):  
Semra Tibebu ◽  
Kevin A. Brown ◽  
Nick Daneman ◽  
Lauren A. Paul ◽  
Sarah A. Buchan
Keyword(s):  
Symptom Onset ◽  
Attack Rate ◽  
Index Case ◽  
Household Size ◽  
Residential Address ◽  
Household Contacts ◽  
Household Transmission ◽  
Case Characteristics ◽  
Index Cases

AbstractIn this population-wide study in Ontario, Canada, we investigated the household secondary attack rate (SAR) to understand its relationship to household size and index case characteristics. We identified all patients with confirmed COVID-19 between July 1 and November 30, 2020. Cases within households were matched based on reported residential address; households were grouped based on the number of household contacts. The majority of households (68.2%) had a SAR of 0%, while 3,442 (11.7%) households had a SAR ≥75%. Overall household SAR was 19.5% and was similar across household sizes, but varied across index case characteristics. Households where index cases had longer delays between symptom onset and test seeking, households with older index cases, households with symptomatic index cases, and larger households located in diverse neighborhoods, were associated with greater household SAR. Our findings present characteristics associated with greater household SARs and proposes immediate testing as a method to reduce household transmission and incidence of COVID-19.

scholarly journals Transmission and serotype features of hand foot mouth disease in household contacts in Dong Thap, Vietnam

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Cuong Quoc Hoang ◽  
Thao Thanh Thi Nguyen ◽  
Nguyen Xuan Ho ◽  
Hai Duc Nguyen ◽  
An Binh Nguyen ◽  
...  
Keyword(s):  
Attack Rate ◽  
Neutralizing Antibodies ◽  
Index Case ◽  
Fold Increase ◽  
Mouth Disease ◽  
Rt Pcr ◽  
Household Contacts ◽  
Two Samples ◽  
Household Members ◽  
Index Cases

Abstract Background Hand, foot and mouth disease (HFMD) has emerged as a major public health issue in Vietnam since 2003. We aimed to investigate the household transmission of HFMD and its causative viruses from 150 households in a high incidence province in Vietnam. Methods A longitudinal study was conducted in patients presenting to the provincial hospital with a HFMD-like syndrome, along with their household members between April and August 2014 in Dong Thap Province. Each participant was followed up for 2 weeks. We enrolled 150 patients aged under 15 who were clinically diagnosed with HFMD in Dong Thap Hospital, 600 household members, and 581/600 household members completed the study. All participants were interviewed using a standard questionnaire. Throat swabs and blood samples were taken for molecular detection of viruses and assessment of neutralizing antibodies, respectively. Index cases were defined using a clinical case definition, household contact cases were defined using a similar definition applied to the 2 weeks before admission and 2 weeks after discharge of the index case. Characteristics of index cases, household contacts, the attack rate, serotype features and related factors of HFMD were reported. Result Among 150 index cases, 113 were laboratory confirmed: 90/150 were RT-PCR-positive, 101/142 had a ≥ 4-fold increase of neutralizing antibody against Enterovirus A71 (EV-A71), Coxsackievirus (CV) A6 or CV-A16 across the two samples collected. 80/150 (53%) were males, and 45/150 (30%) were under the age of 1. The predominant serotype was CV-A6, identified in 57/87 (65.5%) of the specimens. No deaths were reported. Among 581 household contacts, 148 were laboratory confirmed: 12/581 were RT-PCR-positive, 142/545 had a ≥ 4-fold increase of neutralizing antibodies against EV-A71, CV-A6 or CV-A16; 4 cases experienced HFMD in the past 4 weeks. Attack rate among household contacts was 148/581 (25.5%). In 7/12 (58%) instances, the index and secondary cases were infected with the same serotype. Having a relationship to index case was significantly associated with EV infection. Conclusion The attack rate among household contacts was relatively high (25.5%) in this study and it seems justified to also consider the household setting as an additional target for intervention programs.

scholarly journals Risk of Secondary Household Transmission of COVID-19 from Health Care Workers in a Hospital in Spain

Epidemiologia ◽  
2021 ◽  
Vol 3 (1) ◽  
pp. 1-10
Author(s):  
Miren Remón-Berrade ◽  
Sara Guillen-Aguinaga ◽  
Isabel Sarrate-Adot ◽  
Maria Pilar Garcia-Garcia ◽  
Maria del Carmen Lerga-Berruezo ◽  
...  
Keyword(s):  
Risk Factors ◽  
Health Care ◽  
Health Care Workers ◽  
Attack Rate ◽  
Index Case ◽  
Acute Infection ◽  
Transmission Risk ◽  
Household Contacts ◽  
Care Workers ◽  
Index Cases

Background: Hospital health care workers are at high risk of developing COVID-19 and transmitting the disease to their family upon returning home; the aim here is to estimate the secondary attack rate of COVID-19 in household contacts of health care workers and their transmission risk factors. Material and Methods: COVID-19 cases in the health care workers of an academic hospital in Pamplona, Spain, from 2 March to 26 May 2020, were followed up. The secondary attack rate (SAR) was estimated from cases in household contacts of index cases and their risk factors by Poisson regression. Results: 89 index cases were studied from 99 notified cases in health care workers (89.0%), excluding secondary cases or those who lived alone. Forty-six secondary cases confirmed by the laboratory were found among 326 household contacts, a secondary attack rate of 14.11% (95% CI 10.75–18.31), and 33 household contacts with acute infection symptoms without microbiologic confirmation 10.12% (95% CI 7.30–13.87). Considering all the cases, the secondary attack rate was 27.3 (95% CI 22.75–32.38). Risk factors were the gender and profession of the index case, the number of people living in the household, and the number of persons per bedroom. When the index case health worker used a single room, it had a protective effect, with an incidence rate ratio (IRR) of 0.493 (95% CI 0.246–0.985); Conclusions: The secondary attack rate found among household contacts of health care workers is high. The preventive isolation of health care workers in individual rooms in their house may reduce the transmission in their families.

scholarly journals High transmissibility of COVID-19 near symptom onset

2020 ◽  
Author(s):  
Hao-Yuan Cheng ◽  
Shu-Wan Jian ◽  
Ding-Ping Liu ◽  
Ta-Chou Ng ◽  
Wan-Ting Huang ◽  
...  
Keyword(s):  
Symptom Onset ◽  
Attack Rate ◽  
Paired Data ◽  
Rapid Reduction ◽  
Social Distancing ◽  
Household Contacts ◽  
Exposure Windows ◽  
Index Cases ◽  
Over Time ◽  
Close Contacts

AbstractBackgroundThe dynamics of coronavirus disease 2019 (COVID-19) transmissibility after symptom onset remains unknown.MethodsWe conducted a prospective case-ascertained study on laboratory-confirmed COVID-19 cases and their contacts. Secondary clinical attack rate (considering symptomatic cases only) was analyzed for different exposure windows after symptom onset of index cases and for different exposure settings.ResultsThirty-two confirmed patients were enrolled and 12 paired data (index-secondary cases) were identified among the 1,043 contacts. The secondary clinical attack rate was 0.9% (95% CI 0.5–1.7%). The attack rate was higher among those whose exposure to index cases started within five days of symptom onset (2.4%, 95% CI 1.1–4.5%) than those who were exposed later (zero case from 605 close contacts, 95% CI 0–0.61%). The attack rate was also higher among household contacts (13.6%, 95% CI 4.7–29.5%) and non- household family contacts (8.5%, 95% CI 2.4–20.3%) than that in healthcare or other settings. The higher secondary clinical attack rate for contacts near symptom onset remained when the analysis was restricted to household and family contacts. There was a trend of increasing attack rate with the age of contacts (p for trend < 0.001).ConclusionsHigh transmissibility of COVID-19 near symptom onset suggests that finding and isolating symptomatic patients alone may not suffice to contain the epidemic, and more generalized social distancing measures are required. Rapid reduction of transmissibility over time implies that prolonged hospitalization of mild cases might not be necessary in large epidemics.

scholarly journals A meta-analysis on the role of children in SARS-CoV-2 in household transmission clusters

2020 ◽  
Author(s):  
Yanshan Zhu ◽  
Conor J Bloxham ◽  
Katina D Hulme ◽  
Jane E Sinclair ◽  
Zhen Wei Marcus Tong ◽  
...  
Keyword(s):  
Confidence Interval ◽  
Risk Ratio ◽  
Attack Rate ◽  
Index Case ◽  
Meta Analysis ◽  
Household Contacts ◽  
Household Transmission ◽  
Potential Vaccine ◽  
Index Cases

Abstract The role of children in the spread of SARS-CoV-2 remains highly controversial. To address this issue, we performed a meta-analysis of the published literature on household SARS-CoV-2 transmission clusters (n=213 from 12 countries). Only 8 (3.8%) transmission clusters were identified as having a paediatric index case. Asymptomatic index cases were associated with a lower secondary attack in contacts than symptomatic index cases (estimate risk ratio [RR], 0.17; 95% confidence interval [CI], 0.09-0.29). To determine the susceptibility of children to household infections the secondary attack rate (SAR) in paediatric household contacts was assessed. The secondary attack rate in paediatric household contacts was lower than in adult household contacts (RR, 0.62; 95% CI, 0.42-0.91). These data have important implications for the ongoing management of the COVID-19 pandemic, including potential vaccine prioritization strategies.

scholarly journals A meta-analysis on the role of children in SARS-CoV-2 in household transmission clusters

2020 ◽  
Author(s):  
Yanshan Zhu ◽  
Conor J. Bloxham ◽  
Katina D. Hulme ◽  
Jane E. Sinclair ◽  
Zhen Wei Marcus Tong ◽  
...  
Keyword(s):  
Confidence Interval ◽  
Family Member ◽  
Attack Rate ◽  
Index Case ◽  
Meta Analysis ◽  
Household Contacts ◽  
Household Transmission ◽  
Potential Vaccine ◽  
Index Cases

ABSTRACTThe role of children in the spread of SARS-CoV-2 remains highly controversial. To address this issue, we performed a meta-analysis of the published literature on household SARS-CoV-2 transmission clusters (n=213 from 12 countries). Only 8 (3.8%) transmission clusters were identified as having a paediatric index case. Asymptomatic index cases were associated with a lower secondary attack in contacts than symptomatic index cases (estimate risk ratio [RR], 0.17; 95% confidence interval [CI], 0.09-0.29). To determine the susceptibility of children to household infections the secondary attack rate (SAR) in paediatric household contacts was assessed. The secondary attack rate in paediatric household contacts was lower than in adult household contacts (RR, 0.62; 95% CI, 0.42-0.91). These data have important implications for the ongoing management of the COVID-19 pandemic, including potential vaccine prioritization strategies.40-word summaryIn household transmission clusters of SARS-CoV-2 children are unlikely to be the index case. Children are also less likely than adults to be infected with SARS-CoV-2 from a family member.

scholarly journals Investigation of Four Clusters of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) in Rwanda, 2020

2021 ◽  
Vol 18 (13) ◽  
pp. 7018
Author(s):  
Olivier Nsekuye ◽  
Edson Rwagasore ◽  
Marie Aime Muhimpundu ◽  
Ziad El-Khatib ◽  
Daniel Ntabanganyimana ◽  
...  
Keyword(s):  
High Risk ◽  
Severe Acute Respiratory Syndrome ◽  
Symptom Onset ◽  
Attack Rate ◽  
Positive Sample ◽  
Contact Tracing ◽  
Face To Face ◽  
Laboratory Confirmation ◽  
Closed Environment ◽  
Index Cases

We reported the findings of the first Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) four clusters identified in Rwanda. Case-investigations included contact elicitation, testing, and isolation/quarantine of confirmed cases. Socio-demographic and clinical data on cases and contacts were collected. A confirmed case was a person with laboratory confirmation of SARS-CoV-2 infection (PCR) while a contact was any person who had contact with a SARS-CoV-2 confirmed case within 72 h prior, to 14 days after symptom onset; or 14 days before collection of the laboratory-positive sample for asymptomatic cases. High risk contacts were those who had come into unprotected face-to-face contact or had been in a closed environment with a SARS-CoV-2 case for >15 min. Forty cases were reported from four clusters by 22 April 2020, accounting for 61% of locally transmitted cases within six weeks. Clusters A, B, C and D were associated with two nightclubs, one house party, and different families or households living in the same compound (multi-family dwelling). Thirty-six of the 1035 contacts tested were positive (secondary attack rate: 3.5%). Positivity rates were highest among the high-risk contacts compared to low-risk contacts (10% vs. 2.2%). Index cases in three of the clusters were imported through international travelling. Fifteen of the 40 cases (38%) were asymptomatic while 13/25 (52%) and 8/25 (32%) of symptomatic cases had a cough and fever respectively. Gatherings in closed spaces were the main early drivers of transmission. Systematic case-investigations contact tracing and testing likely contributed to the early containment of SARS-CoV-2 in Rwanda.

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