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. 2022 Mar 1;149(3):e2021054178.
doi: 10.1542/peds.2021-054178.

Household Transmission and Clinical Features of SARS-CoV-2 Infections

Huong Q McLean  1 , Carlos G Grijalva  2 , Kayla E Hanson  1 , Yuwei Zhu  2 , Jessica E Deyoe  3 , Jennifer K Meece  1 , Natasha B Halasa  2 , James D Chappell  2 , Alexandra M Mellis  3 , Carrie Reed  3 , Edward A Belongia  1 , H Keipp Talbot  2 , Melissa A Rolfes  3
Affiliations

Household Transmission and Clinical Features of SARS-CoV-2 Infections

Huong Q McLean et al. Pediatrics. .

Abstract

Objectives: Examine age differences in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission risk from primary cases and infection risk among household contacts and symptoms among those with SARS-CoV-2 infection.

Methods: People with SARS-CoV-2 infection in Nashville, Tennessee and central and western Wisconsin and their household contacts were followed daily for 14 days to ascertain symptoms and secondary transmission events. Households were enrolled between April 2020 and April 2021. Secondary infection risks (SIR) by age of the primary case and contacts were estimated using generalized estimating equations.

Results: The 226 primary cases were followed by 198 (49%) secondary SARS-CoV-2 infections among 404 household contacts. Age group-specific SIR among contacts ranged from 36% to 53%, with no differences by age. SIR was lower in primary cases age 12 to 17 years than from primary cases 18 to 49 years (risk ratio [RR] 0.42; 95% confidence interval [CI] 0.19-0.91). SIR was 55% and 45%, respectively, among primary case-contact pairs in the same versus different age group (RR 1.47; 95% CI 0.98-2.22). SIR was highest among primary case-contact pairs age ≥65 years (76%) and 5 to 11 years (69%). Among secondary SARS-CoV-2 infections, 19% were asymptomatic; there was no difference in the frequency of asymptomatic infections by age group.

Conclusions: Both children and adults can transmit and are susceptible to SARS-CoV-2 infection. SIR did not vary by age, but further research is needed to understand age-related differences in probability of transmission from primary cases by age.

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Conflict of interest statement

CONFLICT OF INTEREST DISCLOSURES: Dr Halasa reports grants from Sanofi and Quidel. Dr Grijalva reports grants from Campbell Alliance/Syneos, the National Institutes of Health, the Food and Drug Administration, the Agency for Health Care Research and Quality and Sanofi-Pasteur, and consultation fees from Pfizer, Merck, and Sanofi-Pasteur. Other authors have no conflicts of interest relevant to this article to disclose.

Figures

Figure 1.
Figure 1.
Households and individuals enrolled in a prospective study of SARS-CoV-2 household transmission — Tennessee and Wisconsin, April 2020–April 2021
Figure 2.
Figure 2.
Estimated transmission risk from the primary case and infection risk among household contacts by age — Prospective study of SARS-CoV-2 household transmission, Tennessee and Wisconsin, April 2020–April 2021. Secondary infection risks and risk ratios estimated by using generalized estimating equations, accounting for clustering among household members
Figure 3.
Figure 3.
Estimated secondary infection risk by age of the primary case and age of the household contacts — Prospective study of SARS-CoV-2 household transmission, Tennessee and Wisconsin, April 2020–April 2021
Figure 4.
Figure 4.
Reported symptoms, timing, and duration of symptoms by age group among persons with SARS-CoV-2 infection in a prospective study of SARS-CoV-2 household transmission — Tennessee and Wisconsin, April 2020–April 2021
See this image and copyright information in PMC

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