Household transmission of SARS-CoV-2; a prospective longitudinal study showing higher viral load and transmissibility of the Alpha variant compared to previous strains

Julin, Cathinka H.; Robertson, Anna Hayman; Hungnes, Olav; Tunheim, Gro; Bekkevold, Terese; Laake, Ida; Aune, Idunn Forland; Rykkvin, Rikard; Dorenberg, Dagny Haug; Stene‐Johansen, Kathrine; Berg, Einar Sverre; Bodin, Johanna; Oftung, Fredrik; Steens, Anneke; Næss, Lisbeth Meyer

doi:10.1101/2021.08.15.21261478

Cited by 4 publications

(2 citation statements)

References 34 publications

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“…However, the viral trajectory such as mean peak Ct value, mean proliferative stage duration, clearance stage duration and days from peak between them was different, and the Ct peak in SARS-CoV-2 infection was earlier than SARS-CoV and MERS-CoV [6]. Also, various factors such as individual characters; age, sex, underlying disease, and obesity [3,[7][8][9], virus types of SARS-CoV-2 [10][11][12][13][14][15][16][17][18], treatment, and vaccination history of infectors affected the curve from beginning to end in periods of SARS-CoV-2 infection [19][20][21][22]. So, it is not clear exactly when the viral shedding peak is and how much the difference in viral load at the peak in SARS-CoV-2 virus infection.…”

Section: Many Studies Have Shown That Like Other Respiratory Viruses ...mentioning

confidence: 99%

“…This may have been affected by increased transmissibility of high viral load, or it could also be a warning about the emergence of new variants in a situation where viral sequencing test for the entire infector is impossible [37]. Alpha, delta and omicron variants increased viral load compared to those of wild type [11,12,18,22], and delta was higher than alpha [14], but there was no significant difference between delta and omicron variants [15][16][17].…”

Section: E P U B a H E A D O F P R I N Tmentioning

confidence: 99%

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Viral shedding patterns of symptomatic SARS-CoV-2 infections by periods of variant predominance and vaccination status in Gyeonggi Province, Korea

Choi¹,

Lim²,

Choi³

et al. 2022

Epidemiol Health

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Section: Many Studies Have Shown That Like Other Respiratory Viruses ...mentioning

confidence: 99%

Section: E P U B a H E A D O F P R I N Tmentioning

confidence: 99%

Viral shedding patterns of symptomatic SARS-CoV-2 infections by periods of variant predominance and vaccination status in Gyeonggi Province, Korea

Choi¹,

Lim²,

Choi³

et al. 2022

Epidemiol Health

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Transmission of SARS-CoV-2 within households: a remote prospective cohort study in European countries

et al. 2022

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Household transmission studies are useful to quantify SARS-CoV-2 transmission dynamics. We conducted a remote prospective household study to quantify transmission, and the effects of subject characteristics, household characteristics, and implemented infection control measures on transmission. Households with a laboratory-confirmed SARS-CoV-2 index case were enrolled < 48 h following test result. Follow-up included digitally daily symptom recording, regular nose-throat self-sampling and paired dried blood spots from all household members. Samples were tested for virus detection and SARS-CoV-2 antibodies. Secondary attack rates (SARs) and associated factors were estimated using logistic regression. In 276 households with 920 participants (276 index cases and 644 household members) daily symptom diaries and questionnaires were completed by 95%, and > 85% completed sample collection. 200 secondary SARS-CoV-2 infections were detected, yielding a household SAR of 45.7% (95% CI 39.7–51.7%) and per-person SAR of 32.6% (95%CI: 28.1-37.4%). 126 (63%) secondary cases were detected at enrollment. Mild (aRR = 0.57) and asymptomatic index cases (aRR = 0.29) were less likely to transmit SARS-CoV-2, compared to index cases with an acute respiratory illness (p = 0.03 for trend), and child index cases (< 12 years aRR = 0.60 and 12-18 years aRR = 0.85) compared to adults (p = 0.03 for trend). Infection control interventions in households had no significant effect on transmission. We found high SARs with the majority of transmissions occuring early after SARS-CoV-2 introduction into the household. This may explain the futile effect of implemented household measures. Age and symptom status of the index case influence secondary transmission. Remote, digitally-supported study designs with self-sampling are feasible for studying transmission under pandemic restrictions.

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Susceptibility and infectiousness of SARS-CoV-2 in children versus adults, by variant (wild-type, Alpha, Delta): a systematic review and meta-analysis of household contact studies

Uthman

Lyngse

Anjorin

et al. 2022

Preprint

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Importance: Understanding the susceptibility and infectiousness of children and adolescents in comparison to adults is important to appreciate their role in the COVID-19 pandemic. Objective: To determine SARS-CoV-2 susceptibility and infectiousness of children and adolescents with adults as comparator for three variants (wild-type, Alpha, Delta) in the household setting. We aimed to identify the effects independent of vaccination. Data Sources: We searched EMBASE, PubMed and medRxiv up to January 2022. Additional studies were identified through contacting subject experts. Study Selection: Two reviewers independently identified studies providing secondary attack rates (SAR) for SARS-CoV-2 infection in children (0-9 years), adolescents (10-19 years) or both compared with adults (20 years and older) derived from household data. Data Extraction and Synthesis: Two reviewers independently performed data extraction. We assessed risk of bias of included studies using a critical appraisal checklist and a random-effects meta-analysis model to pool association estimates. Main Outcomes and Measures: Odds ratio (OR) for SARS-CoV-2 infection comparing children and adolescents with adults stratified by wild-type, Alpha, and Delta variant, respectively. Susceptibility was defined as the secondary attack rate (SAR) among susceptible household contacts irrespective of the age of the index case. Infectiousness was defined as the SAR irrespective of the age of household contacts when children/adolescents/adults were the index case. Results: Twenty-eight studies (308,857 contacts) were included in the susceptibility analysis, for Delta only one (large) study was available. Compared to adults children and adolescents were less susceptible to the wild-type and Delta variant, but equally susceptible to the Alpha variant. In the infectiousness analysis, 21 studies (201,199 index cases) were included. Compared to adults, children and adolescents were less infectious when infected with the wild-type and Delta variant. Alpha variant-related infectiousness remained unclear, 0-9 year old children were at least as infectious as adults. SAR among household contacts was highest during circulation of the Alpha variant, lowest during wild-type circulation and intermediate during Delta circulation. Conclusions and Relevance: When considering the potential role of children and adolescents, for each variant susceptibility, infectiousness, age group and overall transmissibility need to be assessed to guide public health policy.

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Household transmission of SARS-CoV-2; a prospective longitudinal study showing higher viral load and transmissibility of the Alpha variant compared to previous strains

Cited by 4 publications

References 34 publications

Viral shedding patterns of symptomatic SARS-CoV-2 infections by periods of variant predominance and vaccination status in Gyeonggi Province, Korea

Viral shedding patterns of symptomatic SARS-CoV-2 infections by periods of variant predominance and vaccination status in Gyeonggi Province, Korea

Transmission of SARS-CoV-2 within households: a remote prospective cohort study in European countries

Susceptibility and infectiousness of SARS-CoV-2 in children versus adults, by variant (wild-type, Alpha, Delta): a systematic review and meta-analysis of household contact studies

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