Household transmission in people infected with SARS-CoV-2 (COVID-19) in Lima-Perú

ABSTRACTObjectiveDescribe the characteristics of SARS-CoV-2 infection among household members with a confirmed primary case of COVID-19 in low burden districts in Metropolitan Lima.Materials and MethodsA retrospective, secondary database review study was conducted. The information was collected from an epidemiological surveillance activity in close contacts (co-inhabitants) in 52 households in Metropolitan Lima with only one member with COVID-19. A reevaluation was carried out in 10 households. Epidemiological and clinical variables were evaluated and its association with the result of the rapid serological test (presence of IgG, IgM or both).ResultsSecondary cases were found in 40 households, which represents an average of 49.9% identification per household. A secondary attack rate of 53.0% (125 cases) was found among cohabitants, with 77.6% of cases being symptomatic (symptomatic / asymptomatic ratio: 3.5). The presence of fever and / or chills was found in 40.0% of people with a positive result, followed by a sore throat, in 39.2%. Ageusia and anosmia were present in 22.4% and 20.8% of cases, respectively. A reevaluation in 40 family members 33.6 ± 2.7 days after the first evaluation, show the persistence of positive IgM and IgG in the 20 positive cases in the first evaluation.ConclusionHaving a primary case of COVID-19 in home, the secondary attack rate of this infection is 53%; however, in a significant proportion of households evaluated there was no positive case, beyond the primary case. The epidemiological and clinical characteristics found in this case were in accordance with what has already been reported in other international series.

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High variability in transmission of SARS-CoV-2 within households and implications for control

PLoS ONE ◽

10.1371/journal.pone.0259097 ◽

2021 ◽

Vol 16 (11) ◽

pp. e0259097

Author(s):

Damon J. A. Toth ◽

Alexander B. Beams ◽

Lindsay T. Keegan ◽

Yue Zhang ◽

Tom Greene ◽

...

Keyword(s):

Test Data ◽

Attack Rate ◽

Serological Test ◽

Close Contact ◽

Antibody Test ◽

High Variability ◽

Test Accuracy ◽

Household Transmission ◽

Wide Range ◽

Test Specificity

Background Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) poses a high risk of transmission in close-contact indoor settings, which may include households. Prior studies have found a wide range of household secondary attack rates and may contain biases due to simplifying assumptions about transmission variability and test accuracy. Methods We compiled serological SARS-CoV-2 antibody test data and prior SARS-CoV-2 test reporting from members of 9,224 Utah households. We paired these data with a probabilistic model of household importation and transmission. We calculated a maximum likelihood estimate of the importation probability, mean and variability of household transmission probability, and sensitivity and specificity of test data. Given our household transmission estimates, we estimated the threshold of non-household transmission required for epidemic growth in the population. Results We estimated that individuals in our study households had a 0.41% (95% CI 0.32%– 0.51%) chance of acquiring SARS-CoV-2 infection outside their household. Our household secondary attack rate estimate was 36% (27%– 48%), substantially higher than the crude estimate of 16% unadjusted for imperfect serological test specificity and other factors. We found evidence for high variability in individual transmissibility, with higher probability of no transmissions or many transmissions compared to standard models. With household transmission at our estimates, the average number of non-household transmissions per case must be kept below 0.41 (0.33–0.52) to avoid continued growth of the pandemic in Utah. Conclusions Our findings suggest that crude estimates of household secondary attack rate based on serology data without accounting for false positive tests may underestimate the true average transmissibility, even when test specificity is high. Our finding of potential high variability (overdispersion) in transmissibility of infected individuals is consistent with characterizing SARS-CoV-2 transmission being largely driven by superspreading from a minority of infected individuals. Mitigation efforts targeting large households and other locations where many people congregate indoors might curb continued spread of the virus.

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High variability in transmission of SARS-CoV-2 within households and implications for control

10.1101/2021.01.29.20248797 ◽

2021 ◽

Author(s):

Damon J.A. Toth ◽

Alexander B. Beams ◽

Lindsay T. Keegan ◽

Yue Zhang ◽

Tom Greene ◽

...

Keyword(s):

Test Data ◽

Attack Rate ◽

Serological Test ◽

Close Contact ◽

Antibody Test ◽

High Variability ◽

Test Accuracy ◽

Household Transmission ◽

Wide Range ◽

Test Specificity

AbstractBackgroundSevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2) poses a high risk of transmission in close-contact indoor settings, which may include households. Prior studies have found a wide range of household secondary attack rates and may contain biases due to simplifying assumptions about transmission variability and test accuracy.MethodsWe compiled serological SARS-CoV-2 antibody test data and prior PCR test reporting from members of more than 9000 Utah households. We paired these data with a probabilistic model of household importation and transmission. We calculated a maximum likelihood estimate of the importation probability, mean and variability of household transmission probability, and sensitivity and specificity of test data. Given our household transmission estimates, we estimated the threshold of non-household transmission required for epidemic growth in the population.ResultsWe estimated that individuals in our study households had a 0.38% (95% CI 0.30% – 0.48%) chance of acquiring SARS-CoV-2 infection outside their household. Our household secondary attack rate estimate was 35% (26% – 47%), substantially higher than the crude estimate of 15% unadjusted for imperfect serological test specificity and other factors. We found evidence for high variability in individual transmissibility, with higher probability of no transmissions or many transmissions compared to standard models. With household transmission at our estimates, the average number of non-household transmissions per case must be kept below 0.40 (0.32 – 0.51) to avoid continued growth of the Utah epidemic.ConclusionsOur findings suggest that crude estimates of household secondary attack rate based on serology data without accounting for false positive tests may underestimate the true average transmissibility, even when test specificity is high. Our finding of potential high variability (overdispersion) in transmissibility of infected individuals is consistent with characterizing SARS-CoV-2 transmission being largely driven by superspreading from a minority of infected individuals. Mitigation efforts targeting large households and other locations where many people congregate indoors might curb continued spread of the virus.

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Secondary attack rate of COVID-19 among contacts and risk factors, Tamil Nadu, March–May 2020: a retrospective cohort study

BMJ Open ◽

10.1136/bmjopen-2021-051491 ◽

2021 ◽

Vol 11 (11) ◽

pp. e051491

Author(s):

Kolandaswamy Karumanagoundar ◽

Mohankumar Raju ◽

Manickam Ponnaiah ◽

Prabhdeep Kaur ◽

Vidhya viswanathan ◽

...

Keyword(s):

Cohort Study ◽

Retrospective Cohort Study ◽

Attack Rate ◽

Retrospective Cohort ◽

Tamil Nadu ◽

Significant Proportion ◽

Primary Case ◽

Factors Associated ◽

Household Contacts ◽

Increased Risk

ObjectiveTo describe the characteristics of contacts of patients with COVID-19 case in terms of time, place and person, to calculate the secondary attack rate (SAR) and factors associated with COVID-19 infection among contacts.DesignA retrospective cohort studySetting and participantsContacts of cases identified by the health department from 14 March 2020to 30 May 2020, in 9 of 38 administrative districts of Tamil Nadu. Significant proportion of cases attended a religious congregation.Outcome measureAttack rate among the contacts and factors associated with COVID-19 positivity.ResultsWe listed 15 702 contacts of 931 primary cases. Of the contacts, 89% (n: 14 002) were tested for COVID-19. The overall SAR was 4% (599/14 002), with higher among the household contacts (13%) than the community contacts (1%). SAR among the contacts of primary cases with congregation exposure were 5 times higher than the contacts of non-congregation primary cases (10% vs 2%). Being a household contact of a primary case with congregation exposure had a fourfold increased risk of getting COVID-19 (relative risk (RR): 16.4; 95% CI: 13 to 20) than contact of primary case without congregation exposure. Among the symptomatic primary cases, household contacts of congregation primaries had higher RR than household contacts of other cases ((RR: 25.3; 95% CI: 10.2 to 63) vs (RR: 14.6; 95% CI: 5.7 to 37.7)). Among asymptomatic primary case, RR was increased among household contacts (RR: 16.5; 95% CI: 13.2 to 20.7) of congregation primaries compared with others.ConclusionOur study showed an increase in disease transmission among household contacts than community contacts. Also, symptomatic primary cases and primary cases with exposure to the congregation had more secondary cases than others.

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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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Characteristics of Household Transmission of COVID-19

Clinical Infectious Diseases ◽

10.1093/cid/ciaa450 ◽

2020 ◽

Vol 71 (8) ◽

pp. 1943-1946 ◽

Cited By ~ 66

Author(s):

Wei Li ◽

Bo Zhang ◽

Jianhua Lu ◽

Shihua Liu ◽

Zhiqiang Chang ◽

...

Keyword(s):

Risk Factors ◽

Attack Rate ◽

Rt Pcr ◽

Spousal Relationship ◽

Telephone Interviews ◽

Household Contacts ◽

Household Transmission ◽

Household Members ◽

Baseline Characteristics ◽

Index Cases

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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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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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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The unwelcome houseguest: secondary household transmission of norovirus

Epidemiology and Infection ◽

10.1017/s0950268817002783 ◽

2017 ◽

Vol 146 (2) ◽

pp. 159-167 ◽

Cited By ~ 7

Author(s):

Z. A. MARSH ◽

S. P. GRYTDAL ◽

J. C. BEGGS ◽

E. LESHEM ◽

P. A. GASTAÑADUY ◽

...

Keyword(s):

Risk Factors ◽

Mixed Models ◽

Rate Ratio ◽

Incidence Rate Ratio ◽

Multivariate Models ◽

Primary Case ◽

Household Level ◽

Household Transmission ◽

The Usa ◽

Household Members

SUMMARYNorovirus is the leading cause of acute gastroenteritis in the USA. Although secondary household transmission of norovirus is frequently reported in outbreaks, little is known about specific risk factors for susceptibility and infectiousness in the household. Three norovirus outbreaks were investigated and data were collected on individuals exposed in the primary outbreak setting and their household members. Potential individual- and household-level risk factors for susceptibility and infectiousness were assessed using univariate and multivariate generalised linear mixed models. In the univariate models, the secondary attack rate (SAR) was significantly higher when living in a household with two or more primary cases (incidence rate ratio (IRR) = 2·1; 95% confidence interval (CI) 1·37–3·29), more than one primary case with vomiting (IRR = 1·9; CI 1·11–3·37), and at least one primary case with diarrhoea (IRR = 3·0; CI 1·46–6·01). After controlling for other risk factors in the multivariate models, the SAR was significantly higher among those living in a household with two or more primary cases (adjusted IRR = 2·0; CI 1·17–3·47) and at least one primary case with diarrhoea (adjusted IRR = 2·8; CI 1·35–5·93). These findings underscore the importance of maintaining proper hygiene and isolating ill household members to prevent norovirus transmission in the household.

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Household Secondary Attack Rate in Gandhinagar district of Gujarat state from Western India

10.1101/2020.09.03.20187336 ◽

2020 ◽

Cited By ~ 1

Author(s):

Komal Shah ◽

Nupur Desai ◽

Deepak Saxena ◽

Dileep Mavalankar ◽

Umang Mishra ◽

...

Keyword(s):

Attack Rate ◽

Contact Time ◽

Fatal Outcome ◽

Western India ◽

Primary Case ◽

Gujarat State ◽

Household Contacts ◽

Line Listing ◽

Average Expenditure ◽

Close Contacts

Objectives: Current retrospective study aims to evaluate household Secondary Attack Rate (SAR) of COVID-19 in Gandhinagar (rural) district of Gujarat, India. Methods: Line-listing of 486 laboratory-confirmed patients, tested between 28th March to 2nd July was collected, out of them 80 (15% of overall sample) cases were randomly selected. Demographic, clinical and household details of cases were collected through telephonic interview. During interview 28 more patients were identified from the same household and were added accordingly. So, study included 74 unrelated cluster of households with 74 primary cases and 386 close contacts. Results: SAR in household contacts of COVID-19 in Gandhinagar was 8.8%. Out of 108, 8 patients expired (7.4%), where higher mortality was observed in primary cases (9.5%) as compared to secondary cases (3%). Occupational analysis showed that majority of the secondary cases (88%) were not working and hence had higher contact time with patient. No out-of-pocket expenditure occurred in 94% of the patients, in remaining 6% average expenditure of 1,49,633INR (2027 USD) was recorded. Conclusions: Key observations from the study are 1) SAR of 8.8% is relatively low and hence home isolation of the cases can be continued 2) Primary case is more susceptible to fatal outcome as compared to secondary cases 3) Government has covered huge population of the COVID-19 patients under cost protection. However, more robust studies with larger datasets are needed to further validate the findings.

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