ArticleMicroorganisms2021
Household Transmission of SARS-CoV-2: A Prospective Longitudinal Study Showing Higher Viral Load and Increased Transmissibility of the Alpha Variant Compared to Previous Strains.
Article in Microorganisms, 2021. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 22 papers, 5 of them syntheses that pooled it.
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
22 citing papers in PubMed, 5 syntheses or guidelines pooled it.
- Impact of disease severity, age, sex, comorbidity, and vaccination on secondary attack rates of SARS-CoV-2: a global systematic review and meta-analysis.BMC infectious diseases · 2025Pooled it
- Pooled it
- SARS-CoV-2 variants of concern in children and adolescents with COVID-19: a systematic review.BMJ open · 2023Pooled it
- The role of children in transmission of SARS-CoV-2 variants of concern within households: an updated systematic review and meta-analysis, as at 30 June 2022.Euro surveillance : bulletin Europeen sur les maladies transmissibles = European communicable disease bulletin · 2023Pooled it
- Systematic review of outbreaks of COVID-19 within households in the European region when the child is the index case.BMJ paediatrics open · 2023Pooled it
- Household transmission of SARS-CoV-2 in the paediatric age group and associated factors: an ambispective community-based study.Frontiers in public health · 2026Observational
- SARS-CoV-2 Infection With Alpha B.1.1.7 Virus Induced Higher Antibody Responses Than Earlier Non-VOC Variants During the First Waves of the COVID-19 Pandemic in Norway.APMIS : acta pathologica, microbiologica, et immunologica Scandinavica · 2025Article
- Research on Dynamic Outpatient Respiratory Nosocomial Infection Control Methods Through Multi-Data Prediction.Risk management and healthcare policy · 2025Article
- Article
- Uncovering strain- and age-dependent innate immune responses to SARS-CoV-2 infection in air-liquid-interface cultured nasal epithelia.iScience · 2024Article
- Predicting severe COVID-19 using readily available admission indicators: SpO2/FiO2 ratio, comorbidity index, and gender.Experimental biology and medicine (Maywood, N.J.) · 2024Article
- Observational
- Viral shedding patterns of symptomatic SARS-CoV-2 infections by periods of variant predominance and vaccination status in Gyeonggi Province, Korea.Epidemiology and health · 2023Article
- Transmission prevention behaviors in US households with SARS-CoV-2 cases in 2020.Frontiers in epidemiology · 2023Article
- Exhaled breath SARS-CoV-2 shedding patterns across variants of concern.International journal of infectious diseases : IJID : official publication of the International Society for Infectious Diseases · 2022Article
- Risk factors for SARS-CoV-2 transmission in student residences: a case-ascertained study.Archives of public health = Archives belges de sante publique · 2022Article
- The amount of SARS-CoV-2 RNA in wastewater relates to the development of the pandemic and its burden on the health system.iScience · 2022Article
- Impact of Age and Symptom Development on SARS-CoV-2 Transmission in Households With Children-Maryland, New York, and Utah, August 2020-October 2021.Open forum infectious diseases · 2022Article
- Transmission of SARS-CoV-2 within households: a remote prospective cohort study in European countries.European journal of epidemiology · 2022Article
- Comparing susceptibility and contagiousness in concurrent outbreaks with a non-VOC and the VOC SARS-CoV-2 variant B.1.1.7 in daycare centers in Hamburg, Germany.International journal of hygiene and environmental health · 2022Article
Corrections and comments
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Authors and funding
17 authors.
Funding
No grant is acknowledged in the PubMed record.
Abstract
We studied the secondary attack rate (SAR), risk factors, and precautionary practices of household transmission in a prospective, longitudinal study. We further compared transmission between the Alpha (B.1.1.7) variant and non-Variant of Concern (non-VOC) viruses. From May 2020 throughout April 2021, we recruited 70 confirmed COVID-19 cases with 146 household contacts. Participants donated biological samples eight times over 6 weeks and answered questionnaires. SARS-CoV-2 infection was detected by real-time RT-PCR. Whole genome sequencing and droplet digital PCR were used to establish virus variant and viral load. SARS-CoV-2 transmission occurred in 60% of the households, and the overall SAR for household contacts was 50%. The SAR was significantly higher for the Alpha variant (78%) compared with non-VOC viruses (43%) and was associated with a higher viral load. SAR was higher in household contacts aged ≥40 years (69%) than in younger contacts (40-47%), and for contacts of primary cases with loss of taste/smell. Children had lower viral loads and were more often asymptomatic than adults. Sleeping separately from the primary case reduced the risk of transmission. In conclusion, we found substantial household transmission, particularly for the Alpha variant. Precautionary practices seem to reduce SAR, but preventing household transmission may become difficult with more contagious variants, depending on vaccine use and effectiveness.
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Registered trials
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