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

  1. Huong Q. McLean
  2. Carlos G. Grijalva
  3. Kayla E. Hanson
  4. Yuwei Zhu
  5. Jessica E. Deyoe
  6. Jennifer K. Meece
  7. Natasha B. Halasa
  8. James D. Chappell
  9. Alexandra M. Mellis
  10. Carrie Reed
  11. Edward A. Belongia
  12. H. Keipp Talbot
  13. Melissa A. Rolfes

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Abstract

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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  1. Version published to 10.1542/peds.2021-054178
  2. ScreenIT

    SciScore for 10.1101/2021.08.16.21262121: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    EthicsIRB: The study protocol was approved by Institutional Review Boards at VUMC and MCHS.
    Sex as a biological variablenot detected.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.

    Table 2: Resources

    Software and Algorithms
    SentencesResources
    Analyses were performed using SAS 9.4 (SAS Institute Inc., Cary, NC).
    SAS Institute
    suggested: (Statistical Analysis System, RRID:SCR_008567)

    Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).

    Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:
    This study has several limitations. First, delayed identification of index cases prevented complete capture of transmission events. Participants may have become infected, but remain asymptomatic, between the time the index case was tested and study enrollment. Thus, duration of positivity and symptoms captured during the enrollment period may be subject to both right and left censoring and may be an underestimate. Second, we assumed secondary infections among contacts resulted from household exposure rather than community transmission. Ongoing exposure from the community may lead to an overestimation of transmission in household settings, especially among age groups more likely to be exposed outside the household. Although patients were instructed to isolate at home or quarantine while waiting for results,38 compliance may have declined as the pandemic progressed. Third, we did not account for reported interactions between the primary case and contacts before and during illness in the primary case. While physical contact between the primary case and household contacts was common, mask use by the primary case was not common before or after illness onset. Differences in age-related interactions may explain or help clarify associations between age and transmission events. Fourth, the study population was largely non-Hispanic White, and findings may not be generalizable to other racial and ethnic groups. Finally, small sample size limited the precision of estimates of SIR and our...

    Results from TrialIdentifier: No clinical trial numbers were referenced.

    Results from Barzooka: We did not find any issues relating to the usage of bar graphs.

    Results from JetFighter: We did not find any issues relating to colormaps.

    Results from rtransparent:
    • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
    • Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
    • No protocol registration statement was detected.

    Results from scite Reference Check: We found no unreliable references.

    About SciScore

    SciScore is an automated tool that is designed to assist expert reviewers by finding and presenting formulaic information scattered throughout a paper in a standard, easy to digest format. SciScore checks for the presence and correctness of RRIDs (research resource identifiers), and for rigor criteria such as sex and investigator blinding. For details on the theoretical underpinning of rigor criteria and the tools shown here, including references cited, please follow this link.

  3. Version published to 10.1101/2021.08.16.21262121 on medRxiv