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Two reports show COVID-19 transmission has slowed, while most people still susceptible

Summary

Two new reports provide further confirmation that social distancing measures have reduced transmission of COVID-19 in King County.

Story

The number of COVID-19 infections in King County has been on the decline since the end of March, according to two recent reports that are consistent with data from Public Health – Seattle & King County.

The reports were completed by Bellevue-based Institute for Disease Modeling (IDM) and the Greater Seattle Coronavirus Assessment Network (SCAN), a disease surveillance initiative in partnership with Public Health – Seattle & King County.

The latest report from IDM and SCAN along with Public Health's COVID-19 surveillance data suggest increased confidence that physical distancing measures are leading to a decline in active infections. Projecting forward, if distancing measures were lifted in early May, IDM's new model predicts a rapid rise in the rate of cases that would likely exceed recent peak levels by the end of the month.

Key findings from the reports:

  • IDM estimates that approximately 200 people per 10,000 in King County have been infected with COVID-19. This translates into approximately 46,000 people infected, which is about 10 times the number that had been reported at that time.

  • The IDM model provides information about how many people, on average, will be infected for every one person who has the disease, known as the reproductive rate. In King County, the rate has declined from around three in early March to below the critical threshold of one since March 29, with the best estimate for April 15 at 0.64. Interventions like social distancing are important in driving down and sustaining this number below one.

  • The second data source from SCAN also provides preliminary information about how the virus is spreading in the community. As of April 26, SCAN had tested 8,443 samples from volunteer respondents. Among 5,194 samples from respondents with COVID-like illness (CLI) symptoms, 67 samples tested positive for COVID-19. Of 3,249 samples from people not reporting symptoms, five samples tested positive.

These valuable studies are showing us that there is more COVID-19 in the community than meets the eye, reinforcing the importance of continuing our current distancing measures," said Dr. Jeff Duchin, Health Officer for Public Health – Seattle & King County. "Although transmission has slowed, most people in our area remain vulnerable to infection and there are still too many cases reported each day. We need a better understanding of how people are being infected in order to further reduce the number of COVID-19 illnesses. At this time, staying home and away from others remains our best weapon against COVID-19."

SCAN participation: SCAN is still seeking more participation from children and adolescents, as well as among key demographic groups (Black, Hispanic, or Latinx, and Native Hawaiian or Pacific Islander) to more accurately reflect the population of King County. Individuals and parents of individuals who belong to these groups are encouraged to enroll in the study at scanpublichealth.org. SCAN's enrollment website is available in multiple languages. Click on the drop-down menu on the right-hand side for information in multiple languages.

For more information on the latest findings, view Public Health Insider's recent blog: Update: Latest reports show COVID-19 declining; infections found across King County, most still susceptible.

Testing update at correctional facility

In late April, Public Health deployed a testing team to King County's Maleng Regional Justice Center after six staff members reported testing positive since the pandemic began. One of the 188 staff members tested positive for COVID-19. Eight test results require additional review, while 179 tests came back negative. The Department of Adult and Juvenile Detention continues to test people in custody who exhibit symptoms of COVID-19.

Case updates

Daily totals for new COVID-19 cases and deaths are available on Public Health's Data Dashboard webpage, which updates as soon as data are available, typically between 1-3 p.m.

Isolation and quarantine facilities update

Isolation and quarantine is a proven public health practice for reducing the spread of disease.

Fifty-two people are currently staying in King County isolation, quarantine and recovery facilities. The number of residents at King County's isolation and quarantine sites is included in regular updates provided by Public Health. No other identifying or personal information will be provided.

Additional information

  • Information about COVID-19 and the response in King County, be sure to check our webpage: www.kingcounty.gov/covid
  • Public Health publishes new information frequently through the Public Health Insider blog – please consider becoming a subscriber by choosing the option to "Follow Blog Via Email."