• About Us
    • Contact Us
    • Login
    • ObGFirst
  • COVID-19
  • Alerts
  • OB
  • 2T US Atlas
  • The Genome
  • GYN
    • GYN
    • Sexual Health
  • Primary Care
  • Your Practice
  • #GrandRounds
  • My Bookshelf
  • Now@ObG
  • Media
About Us Contact Us Login ObGFirst
  • COVID-19
  • Alerts
  • OB
  • 2T US Atlas
  • The Genome
  • GYN
    • 0 CME Hours
    • GYN
    • Sexual Health
  • Primary Care
  • Your Practice
  • #GrandRounds
  • My Bookshelf
  • Now@ObG
  • Media
#Grand Rounds

Household SARS-CoV-2 Transmission Risks: Presymptomatic vs Symptomatic

image_pdfFavoriteLoadingFavorite

BACKGROUND AND PURPOSE:

  • Li et al. (Lancet Infectious Diseases, 2021) examined household transmissibility of SARS-CoV-2 as well as risk factors associated with infectivity and susceptibility to infection

METHODS:

  • Retrospective cohort study
  • Setting
    • Wuhan, China
    • Cases confirmed between Dec 2, 2019, and April 18, 2020
  • Participants
    • All individuals positive for SARS-CoV-2 (lab or clinical tests) and their households
    • Asymptomatic and symptomatic
  • Study design
    • Household definition: Groups of family members who did not necessarily live at the same address
      • Households were considered epidemiologically linked if they shared common contacts
    •  A statistical transmission model was used to estimate household secondary attack rates and to quantify risk factors associated with infectivity and susceptibility to infection
      • The model accounted for individual-level exposure history
    • The effect of intervention policies on household reproductive number was also assessed
    • Reproductive number was defined as the mean number of household contacts a case can infect

RESULTS:

  • 27,101 households
    • Primary cases: 29,578
    • Household contacts: 57,581
  • Estimated secondary attack rate: 15.6% (95% CI, 15.2 to 16.0%)
    • This assumed a mean incubation period of 5 days and a max infectious period of 22 days
  • Individuals aged ≥60 years were at a higher risk of infection than all other age groups
  • Infants (≤1 year) were more likely to be infected than
    • Children aged 2 to 5 years: odds ratio (OR) 2.20 (95% CI, 1.40 to 3.44)
    • Children aged 6 to 12 years: OR 1.53 (95% CI, 1.01 to 2.34)
  • Given the same exposure time, children and adolescents <20 years were more likely to infect others than were adults ≥60 years
    • OR 1.58 (95% CI, 1.28 to 1.95)
  • Asymptomatic individuals were much less likely to infect others than were symptomatic individuals
    • OR 0.21 (95% CI, 0.14 to 0.31)
  • Symptomatic cases were more likely to infect others before their symptoms started than they were after symptom onset
    • OR 1.42 (95% CI, 1.30 to 1.55)
  • After mass isolation of cases, quarantine of household contacts, and restriction of movement policies were implemented, household reproductive numbers declined
    • Primary cases: 52% decline
      • From OR 0.25 (95% CI, 0.24 to 0.26) to 0.12 (95% CI, 0.10 to 0.13)
    • Secondary cases: 63% decline
      • From OR 0.17 (95% CI, 0.16 to 0.18) to 0.063 (95% CI, 0.057 to 0.070)

CONCLUSION:

  • Within households
    • Children were more likely to infect others than were older individuals, but children were also less susceptible to infection
    • Presymptomatic cases were more infectious
    • Asymptomatic cases were less infectious
  • The authors conclude

Although children and adolescents were much less likely to have severe disease, they were as likely as adults to develop symptoms

We confirmed the high infectiousness of cases during the incubation period and found asymptomatically infected individuals were about 80% less infectious than symptomatic cases

Learn More – Primary Sources:

Household transmission of SARS-CoV-2 and risk factors for susceptibility and infectivity in Wuhan: a retrospective observational study

Get COVID-19 Research Summaries Direct to Your Phone, with ObGFirst

ObGFirst® – Try It Free! »

image_pdfFavoriteLoadingFavorite
< Previous
All #Grand Rounds Posts
Next >

Related ObG Topics:

A Possible Explanation for Differing Rates of COVID-19 Infection between Adults and Children
Further Evidence for a 5 Day COVID-19 Incubation Period
Do Warmer Temperatures Decrease the Incidence of COVID-19?

Sections

  • COVID-19
  • Alerts
  • OB
  • GYN
    • GYN
    • Sexual Health
  • 2T US Atlas
  • The Genome
  • Primary Care
  • Your Practice
  • #Grand Rounds
  • My Bookshelf
  • Now@ObG
  • Media

ObG Library

  • Hysteroscopy
  • Fertility
  • Site Map/
  • © ObG Project/
  • Terms and Conditions/
  • Privacy/
  • Contact Us/
© ObG Project
SSL Certificate


  • Already an ObGFirst Member?
    Welcome back

    Log In

    Want to sign up?
    Get guideline notifications
    CME Included

    Sign Up

Get Guideline Alerts Direct to Your Phone
Try ObGFirst Free!

Sign In

Lost your password?

Sign Up for ObGFirst and Stay Ahead

  • - Professional guideline notifications
  • - Daily summary of a clinically relevant
    research paper
  • - Includes 1 hour of CME every month

ObGFirst Free Trial

Already a Member of ObGFirst®?

Please log in to ObGFirst to access the 2T US Atlas

Password Trouble?

Not an ObGFirst® Member Yet?

  • - Access 2T US Atlas
  • - Guideline notifications
  • - Daily research paper summaries
  • - And lots more!
ObGFirst Free Trial

Media - Internet

Computer System Requirements

OBG Project CME requires a modern web browser (Internet Explorer 10+, Mozilla Firefox, Apple Safari, Google Chrome, Microsoft Edge). Certain educational activities may require additional software to view multimedia, presentation, or printable versions of their content. These activities will be marked as such and will provide links to the required software. That software may be: Adobe Flash, Apple QuickTime, Adobe Acrobat, Microsoft PowerPoint, Windows Media Player, or Real Networks Real One Player.

Disclosure of Unlabeled Use

This educational activity may contain discussion of published and/or investigational uses of agents that are not indicated by the FDA. The planners of this activity do not recommend the use of any agent outside of the labeled indications.

The opinions expressed in the educational activity are those of the faculty and do not necessarily represent the views of the planners. Please refer to the official prescribing information for each product for discussion of approved indications, contraindications, and warnings.

Disclaimer

Participants have an implied responsibility to use the newly acquired information to enhance patient outcomes and their own professional development. The information
presented in this activity is not meant to serve as a guideline for patient management. Any procedures, medications, or other courses of diagnosis or treatment discussed or suggested in this activity should not be used by clinicians without evaluation of their patient’s conditions and possible contraindications and/or dangers in use, review of any applicable manufacturer’s product information, and comparison with recommendations of other authorities.

Jointly provided by

NOT ENOUGH CME HOURS

It appears you don't have enough CME Hours to take this Post-Test. Feel free to buy additional CME hours or upgrade your current CME subscription plan

Subscribe

JOIN OBGFIRST AND GET CME/CE CREDITS

One of the benefits of an ObGFirst subscription is the ability to earn CME/CE credits from the ObG entries you read. Tap the button to learn more about ObGFirst

Learn More
Leaving ObG Website

You are now leaving the ObG website and on your way to PRIORITY at UCSF, an independent website. Therefore, we are not responsible for the content or availability of this site