Characteristics of Household Transmission of COVID-19

Abstract Background Since December 2019, SARS-CoV-2 has extended to most parts of China with >80 000 cases and to at least 100 countries with >60 000 international cases as of 15 March 2020. Here we used a household cohort study to determine the features of household transmission of COVID-19. Methods A total of 105 index patients and 392 household contacts were enrolled. Both index patients and household members were tested by SARS-CoV-2 RT-PCR. Information on all recruited individuals was extracted from medical records and confirmed or supplemented by telephone interviews. The baseline characteristics of index cases and contact patients were described. Secondary attack rates of SARS-CoV-2 to contact members were computed and the risk factors for transmission within the household were estimated. Results Secondary transmission of SARS-CoV-2 developed in 64 of 392 household contacts (16.3%). The secondary attack rate to children was 4% compared with 17.1% for adults. The secondary attack rate to the contacts within the households with index patients quarantined by themselves since onset of symptoms was 0% compared with 16.9% for contacts without quarantined index patients. The secondary attack rate to contacts who were spouses of index cases was 27.8% compared with 17.3% for other adult members in the households. Conclusions The secondary attack rate of SARS-CoV-2 in household is 16.3%. Age of household contacts and spousal relationship to the index case are risk factors for transmission of SARS-CoV-2 within a household. Quarantine of index patients at home since onset of symptoms is useful to prevent the transmission of SARS-Co-2 within a household.

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

BMC Infectious Diseases ◽

10.1186/s12879-019-4583-1 ◽

2019 ◽

Vol 19 (1) ◽

Cited By ~ 3

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.

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401. Natural History of Shedding and Household Transmission of Severe Acute Respiratory Syndrome Coronavirus 2 Using Intensive High-Resolution Sampling

Open Forum Infectious Diseases ◽

10.1093/ofid/ofab466.602 ◽

2021 ◽

Vol 8 (Supplement_1) ◽

pp. S302-S302

Author(s):

Jonathan Altamirano ◽

Prasanthi Govindarajan ◽

Andra Blomkalns ◽

Sean Leary ◽

India Robinson ◽

...

Keyword(s):

Risk Factors ◽

Index Case ◽

Socioeconomic Indicators ◽

Rt Pcr ◽

Viral Spread ◽

Household Contacts ◽

Household Transmission ◽

Secondary Infections ◽

History Of ◽

Index Cases

Abstract Background In order to mitigate the spread of SARS-CoV-2 and the COVID-19 pandemic, public health officials have recommended self-isolation, self-quarantine of exposed household contacts (HHC), and mask use to limit viral spread within households and communities. While household transmission of SARS-CoV-2 is common, risk factors for HHC transmission are poorly understood. Methods In this prospective cohort study, we enrolled 37 households with at least one reverse transcription polymerase chain reaction-confirmed (RT-PCR) COVID-19 index case from March 2020 - March 2021, in order to calculate secondary attack rates (SAR) and define risk factors for secondary infections. Participants were tested daily for SARS-CoV-2 via RT-PCR, using self-collected lower nasal samples. Households were followed until all members tested negative for seven consecutive days. We collected demographics, medical conditions, relationship to index case, and socioeconomic indicators. Subgroup data analysis was conducted and stratified by positivity status. Results Of 99 enrolled participants, 37 were index cases and 62 were household contacts (HHC), of whom 25 HHC were infected (40.3%). Secondary attack rate (SAR) was highest among adults caring for a parent (n=4/4, 100%) and parents of index cases (5/10, 50%). Households whose income came from service work had greater risk of transmission compared to households whose primary income was technology (n=5/7; 71.4% vs 3/8; 37.5% respectively). Pediatric contacts were at lower risk of infection when compared to adult contacts (n=5/18, 27.8% vs n=20/44, 45.5% respectively). Conclusion This study suggests that household transmission represents a key source of community-based infection of SARS-CoV-2. Allocating resources for education/training regarding prevention among infected individuals and their close contacts will be critical for control of future outbreaks of SARS-CoV-2. Disclosures All Authors: No reported disclosures

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High attack rates of SARS-CoV-2 infection through household-transmission: a prospective study

10.1101/2020.11.02.20224485 ◽

2020 ◽

Author(s):

Kanika Kuwelker ◽

Fan Zhou ◽

Bjørn Blomberg ◽

Sarah Lartey ◽

Karl Albert Brokstad ◽

...

Keyword(s):

Attack Rate ◽

Index Case ◽

Rt Pcr ◽

Younger Adults ◽

Household Transmission ◽

Antibody Titres ◽

Household Members ◽

Polymerase Chain ◽

A Prospective Study ◽

Rule Out

AbstractBackgroundHousehold attack rates of SARS-CoV-2 ranging from 7% to 38% have been reported, using reverse transcription polymerase chain reaction (RT-PCR) of respiratory samples. Lower attack rates were described in children, but the importance of age in household transmission dynamics remains to be clarified.MethodsDuring the first month of the outbreak, we enrolled 112 households (291 participants) in a prospective case-ascertained study, collecting demographic and clinical data from index cases and household members. Sera were collected 6-8 weeks after index case symptom onset, to measure SARS-CoV-2-specific antibodies.FindingsT Local Ethics Committee (#118664). he overall household attack rate was 45% assessed by seroconversion, and 47% when also including RT-PCR positives. Serology identified a significantly higher number of infected household members than RT-PCR. Attack rates were equally high in children (43%) and young adults (46%), but highest among household members aged ≥60 years (72%). The attack rate was 16% in asymptomatic household members, and 42% in RT-PCR negative household members. Older adults generally had higher antibody titres than younger adults. The risk of household transmission was higher when the index case had fever or dyspnoea during acute illness but not associated with cough.InterpretationSerological assays provide more accurate estimates of household secondary attack rate than RT-PCR, especially among children who have a lower RT-PCR positivity rate. Children are equally susceptible to infection as adults, but elderly show higher attack rates. Negative RT-PCR or lack of symptoms are not sufficient to rule out infection in household members.FundingHelse Vest (F-11628), Trond Mohn Foundation (TMS2020TMT05).

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Role of children in household transmission of COVID-19

Archives of Disease in Childhood ◽

10.1136/archdischild-2020-319910 ◽

2020 ◽

pp. archdischild-2020-319910 ◽

Cited By ~ 13

Author(s):

Jieun Kim ◽

Young June Choe ◽

Jin Lee ◽

Young Joon Park ◽

Ok Park ◽

...

Keyword(s):

Attack Rate ◽

Index Case ◽

Clinical Findings ◽

International Travel ◽

Contact Tracing ◽

Secondary Case ◽

Household Transmission ◽

Household Members ◽

Index Cases

ObjectiveTransmissibility of COVID-19 by children in the household is not clear. Herein, we describe children’s role in household transmission of COVID-19.Design and settingAll paediatric COVID-19 index cases and their household members reported from 20 January to 6 April 2020 in South Korea were reviewed. The secondary attack rate (SAR) from child index case to household secondary case was calculated. Epidemiological and clinical findings of child index case-household secondary case pair was assessed.ResultsA total of 107 paediatric COVID-19 index cases and 248 of their household members were identified. One pair of paediatric index-secondary household case was identified, giving a household SAR of 0.5% (95% CI 0.0% to 2.6%). The index case was self-quarantined at home after international travel, stayed in her room, but shared a meal table with the secondary case.ConclusionThe SAR from children to household members was low in the setting of social distancing, underscoring the importance of rigorous contact tracing and early isolation in limiting transmission within households.

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Household SARS-CoV-2 transmission and children: a network prospective study

Clinical Infectious Diseases ◽

10.1093/cid/ciab228 ◽

2021 ◽

Cited By ~ 2

Author(s):

Antoni Soriano-Arandes ◽

Anna Gatell ◽

Pepe Serrano ◽

Mireia Biosca ◽

Ferran Campillo ◽

...

Keyword(s):

Risk Factors ◽

Index Case ◽

Viral Transmission ◽

Transmission Risk ◽

School Interventions ◽

Household Transmission ◽

Household Members ◽

School Period ◽

Index Cases

Abstract Background The role of children in household transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) remains uncertain. Here, we describe the epidemiological and clinical characteristics of children with COVID-19 in Catalonia (Spain) and investigate the dynamics of household transmission. Methods Prospective, observational, multicenter study performed during summer and school periods (1 July-31 October, 2020), in which epidemiological and clinical features, and viral transmission dynamics were analyzed in COVID-19 patients <16 years. A pediatric index case was established when a child was the first individual infected within a household. Secondary cases were defined when another household member tested positive for SARS-CoV-2 before the child. The secondary attack rate (SAR) was calculated, and logistic regression was used to assess associations between transmission risk factors and SARS-CoV-2 infections. Results The study included 1040 COVID-19 patients <16 years. Almost half (47.2%) were asymptomatic, 10.8% had comorbidities, and 2.6% required hospitalization. No deaths were reported. Viral transmission was common among household members (62.3%). More than 70% (756/1040) of pediatric cases were secondary to an adult, whereas 7.7% (80/1040) were index cases. The SAR was significantly lower in households with COVID-19 pediatric index cases during the school period relative to summer (p=0.02), and when compared to adults (p=0.006). No individual or environmental risk factors associated with the SAR were identified. Conclusions Children are unlikely to cause household COVID-19 clusters or be major drivers of the pandemic even if attending school. Interventions aimed at children are expected to have a small impact on reducing SARS-CoV-2 transmission.

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Secondary Attack Rate among Non-Spousal Household Contacts of Coronavirus Disease 2019 in Tsuchiura, Japan, August 2020–February 2021

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18178921 ◽

2021 ◽

Vol 18 (17) ◽

pp. 8921

Author(s):

Tsuyoshi Ogata ◽

Fujiko Irie ◽

Eiko Ogawa ◽

Shifuko Ujiie ◽

Aina Seki ◽

...

Keyword(s):

Risk Factors ◽

Attack Rate ◽

Transmission Rate ◽

Diagnostic Delay ◽

Household Size ◽

Household Contacts ◽

Size Number ◽

Mixed Regression ◽

Household Members ◽

Linear Mixed Regression Model

Household secondary attack rate (HSAR) by risk factor might have a higher transmission rate between spouses. We investigated risk factors for the HSAR among non-spousal household contacts of patients with coronavirus disease 2019 (COVID-19). We studied household contacts of index cases of COVID-19 in Tsuchiura, Japan, from August 2020 through February 2021. The HSARs of the whole household contacts and non-spousal household contacts were calculated and compared across risk factors. We used a generalized linear mixed regression model for multivariate analysis. We enrolled 496 household contacts of 236 index COVID-19 cases. The HSAR was higher for spousal household contacts (37.8%) than for other contacts (21.2%). The HSAR was lower for non-spousal household contacts with a household size (number of household members) of two (18.2%), compared to the HSAR for contacts with a household size ≥4. The HSAR was higher for non-spousal household contacts of index patients with ≥3 days of diagnostic delay (period between onset and diagnosis) (26.0%) compared to those with ≤2 days’ delay (12.5%) (p = 0.033). Among non-spousal household contacts, the HSAR was low for those with a household size of two and was high for contacts of index patients with a long diagnostic delay.

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High secondary attack rate and persistence of SARS-CoV-2 antibodies in household transmission study participants, Finland 2020

10.1101/2021.07.25.21260925 ◽

2021 ◽

Author(s):

Timothee Dub ◽

Hanna Nohynek ◽

Lotta Hagberg ◽

Oona Liedes ◽

Anu Haveri ◽

...

Keyword(s):

Attack Rate ◽

Neutralizing Antibodies ◽

Serum Samples ◽

Household Transmission ◽

Transmission Study ◽

Household Members ◽

Transmission Studies ◽

Study Participants ◽

Index Cases

Background Household transmission studies offer the opportunity to assess both secondary attack rate and persistence of SARS-CoV-2 antibodies over time. Methods We invited confirmed COVID-19 cases and their household members to attend up to four household visits with collection of nasopharyngeal and serum samples over 28 days after index case onset. We calculated secondary attack rates (SAR) based on the presence of SARS-CoV-2 nucleoprotein IgG antibodies (IgG Ab) and/or neutralizing antibodies (NAb) overall and per households. Three and six months later, we assessed the persistence of SARS-CoV-2 antibodies. Findings We recruited 39 index cases and 90 household members. Among 87 household members evaluated, SAR was 48% (n=42), including 37 symptomatic secondary cases. In total, 80/129 (62%) participants developed both IgG Ab and NAb, while three participants only developed IgG Ab. Among participants who had both IgG Ab and NAb during the initial follow-up, 68/69 (99%) and 63/70 (90%) had IgG Ab and NAb at 3 months, while at 6 months, 59/75 (79%) and 63/75 (84%) had IgG Ab and NAb, respectively. Participants who required hospital care had initially 5-fold IgG Ab concentrations compared to cases with mild symptoms and 8-fold compared to asymptomatic cases. Interpretation Following detection of a COVID-19 case in a household, other members had a high risk of becoming infected. Follow-up of participants showed strong persistence of antibodies in most cases. Funding This study was supported by THL coordinated funding for COVID-19 research (Finnish Government's supplementary budget) and by the Academy of Finland (Decision number 336431).

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

Epidemiologia ◽

10.3390/epidemiologia3010001 ◽

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.

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Efficacy of baloxavir marboxil on household transmission of influenza infection

Journal of Pharmaceutical Health Care and Sciences ◽

10.1186/s40780-020-00178-4 ◽

2020 ◽

Vol 6 (1) ◽

Author(s):

Takumi Umemura ◽

Yoshikazu Mutoh ◽

Takato Kawamura ◽

Masayuki Saito ◽

Takahito Mizuno ◽

...

Keyword(s):

Risk Factors ◽

Influenza Virus ◽

Attack Rate ◽

Influenza Infection ◽

Alternative Therapy ◽

Virus Transmission ◽

Household Transmission ◽

Independent Risk Factors ◽

Household Members ◽

Oseltamivir Phosphate

Abstract Background Baloxavir marboxil (baloxavir) is a new anti-influenza virus agent that is comparable to oseltamivir phosphate (oseltamivir). Since the efficacy of baloxavir in preventing household transmission of influenza is not well established, we compared the secondary household influenza virus transmission rates between patients on baloxavir vs oseltamivir. Methods Between October 2018 and March 2019, we enrolled index patients (diagnosed with influenza and treated with baloxavir or oseltamivir) and household members. The secondary attack rate of household members was compared between index patients treated with baloxavir vs oseltamivir. Risk factors of household transmission were determined using multivariate logistic analyses. Results In total, 169 index patients with influenza type A were enrolled. The median age was 27.0 (interquartile range; 11–57) years. The number of index patients treated with baloxavir and oseltamivir was 49 and 120, respectively. The secondary attack rate was 9.0% (95% confidence interval [CI]: 4.6–15.6) in the baloxavir group and 13.5% (95% CI: 9.8–17.9) in the oseltamivir group. In the multivariate analysis, independent risk factors were 0–6 years of age (odds ratio [OR] 2.78, 95% CI: 1.33–5.82, p < 0.01) and not being on baloxavir treatment. (OR: 0.63, 95% CI: 0.30–1.32, p = 0.22). Conclusion The household secondary attack rate of influenza was comparable in patients treated with baloxavir vs oseltamivir. Therefore, baloxavir can be used as an alternative therapy to oseltamivir in reducing household transmission of influenza. Trial registration Patients in this study were retrospectively registered. https://www.tosei.or.jp/clinical/pdf/2_influenza.pdf.

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

Clinical Infectious Diseases ◽

10.1093/cid/ciaa1825 ◽

2020 ◽

Cited By ~ 2

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.

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