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COVID-19 contact tracing numbers fall, where is tracing best?

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Posted at 5:35 PM, Dec 03, 2021

PHOENIX — New data from Arizona’s largest county shows that in the past six months the number of people notified of COVID-19 exposure has dropped.

Of COVID-19 cases reported from June to November, on average there are around 12,700 close contacts, according to data from Maricopa County’s Public Health Department. Of those, about 1/3 of the contacts are able to be notified of their exposure.

A spokesperson for MCPHD tells ABC15, “If a contact is reported without any contact information or the close contact does not answer the phone, MCDPH is unable to notify them.”

Contact tracing is a tool used to help slow the spread of COVID-19 by identifying positive cases and connecting close exposures to those who came into contact with a positive person.

According to Arizona’s Department of Health Services a case investigator is assigned to a positive case, “An investigator assigned to the case calls the COVID-19 positive individual (the “case”) to collect information about their illness, explore where they may have contracted the disease and to discuss anyone they spent time with (their “contacts”).”

The data shared with ABC15 shows the percent of contacts notified who were able to be reached.

Over the summer, health officials were able to notify 45% of close contacts, but in November that number has dropped to under 22.9%.

Month (2021)Contacts IdentifiedContacts NotifiedContacts Enrolled
n% of Identifiedn% of Identified% of Notified
June155462140.0%29418.9%47.3%
July166174845.0%40924.6%54.7%
August23413725331.0%392816.8%54.2%
September19529534227.4%306915.7%57.5%
October13162360227.4%202915.4%56.3%
November17073390322.9%217212.7%55.6%

A few notes about the data from MCPHD:

  • All counts are based on the month the contact was first imported into our contact tracing system (i.e. someone imported June 30 and contacted July 1 will be counted in the June numbers).
  • Contacts Identified: # of close contacts reported to MCDPH by COVID-19 cases (regardless of whether contact information or the correct contact information is provided)
  • Contacts Notified: # of close contacts that are able to be reached at their correct phone number and notifying them of their exposure. Someone who declines to talk with them more or enroll in Sara Alert for symptom monitoring is still considered “notified”. Incorrect phone numbers and voicemails (even for the correct person) are not considered a notification, they are lost to follow up.
  • Contacts Enrolled: # of close contacts that elect to enroll in post-exposure symptom monitoring in the Sara Alert system.

Will Humble, with the Arizona Public Health Association, tells ABC15 that while contact tracing for the community at large may not be the best use of time, he says for institutions it is still helpful, “it is a good use of time in schools, assisted living centers, skilled nursing facilities, places that provide services for persons with developmental disabilities, contact tracing is still valuable there.”