News Scan for Mar 28, 2022

Contact tracing may have averted 1.4 million US COVID cases in 2 monthsA Centers for Disease Control and Prevention (CDC) modeling study used data from 59 US case investigation and contact tracing (CICT) programs to estimate that the programs prevented 1.11 to 1.36 million COVID-19 cases, and 27,000 to 34,000 hospitalizations over 60 days in winter 2020-21, well before the Delta and Omicron variant surges.

The researchers collected data from Nov 25, 2020, to Jan 23, 2021, for analysis from July to September 2021. The 22 states and 1 territory studied covered 42.5% of the US population, spanned all four US Census regions, and reported data that reflected all 59 federally funded CICT programs.Under a high-impact scenario in which 80% of all interviewed COVID-19 survivors and monitored contacts, as well as 30% of notified contacts, complied 100% with quarantine recommendations, CICT programs prevented 1.11 million infections and 27,231 hospitalizations.In a low-impact scenario in which all COVID-19 survivors and monitored contacts followed quarantine guidelines, those estimates rose to 1.36 million infections and 33,527 hospitalizations.Across all scenarios and jurisdictions, CICT prevented an estimated median of 21.2% (range, 1.3% to 65.8%) of infections not averted by vaccination and nonpharmaceutical interventions.

CICT jurisdictions in the Midwest averted the most cases (1,444 to 1,600 cases per 100,000 people in low- and high-impact scenarios, respectively), while those in the West averted the fewest (488 to 568 cases per 100 000 in the low- and high-impact scenarios).In February 2022, the study authors had previously assessed data from five US states and nine local health districts to estimate that CICT programs