Meghan Weinberg, PhD, MPH and Tiffany Henderson, MPH

The SARS-CoV-2 variant strain B.1.617 and three sublineages (B.1.617.1, B.1.617.2, B.1.617.3) were originally detected in India. On June 14, 2021, the Centers for Disease Control and Prevention (CDC) classified B.1.617.2 (Delta) as a variant of concern (VOC) due to evidence of increased transmissibility and potential reduction in neutralization by some EUA monoclonal antibody treatments and post-vaccination sera and the potential to cause more severe disease¹. CDC currently classifies B.1.617.1 (Kappa) and B.1.617.3 as variants of interest (VOI).

According to the World Health Organization (WHO), B.1.617.2 (Delta) has been identified in at least 96 countries/territories², including the United States where the estimated proportion of B.1.617.2 (Delta) has increased from 10.0% for the two-week period ending June 5 to 20.6% for the two-week period ending June 19³. Both B.1.617.2 (Delta) and B.1.617.1 (Kappa) cases have been confirmed in Michigan.  Recent studies indicate COVID-19 vaccines are effective against variants of concern, including B.1.617.2; however, completion of the series is necessary for maximum protection⁴.

To slow the introduction of variants of concern in Michigan, the Michigan Department of Health and Human Services (MDHHS) recommends that Local Health Departments treat cases with an international travel history during their incubation period (i.e., 14 days prior to symptom onset or positive diagnostic test) as a suspected variant of concern infection and to perform enhanced follow-up.

Enhanced follow-up includes to:

• Re-visit the investigation for both the case and any ill household contacts.
• Confirm isolation was met appropriately.
• Re-check for additional contacts including extending the communicable period back an additional day (i.e., starting the communicable period three days prior to onset or first positive diagnostic test if asymptomatic).
• Recommend appropriate quarantine of contacts without the option for ending quarantine early.
• Recommend testing of all contacts. MDHHS BOL is available for COVID-19 PCR testing.
• Send PCR positive specimens for the index case and epi-linked cases to MDHHS BOL for sequencing.

Guidance for Travelers Returning from International Travel

Upon arriving in the United States, CDC recommends international travelers:

• Get tested with a viral test (e.g., PCR or antigen) 3-5 days after travel. If the traveler has recovered from a documented COVID-19 infection within the last three months, they do not need to be tested after travel unless they are symptomatic.
• Self-monitor for COVID-19 symptoms; isolate and get tested if symptoms develop.
• Should stay home and self-quarantine for 7 days after travel (if not fully vaccinated). Even if they test negative, they should stay home and self-quarantine for 7 days. If they do not get tested, they should stay home and self-quarantine for 10 days. Regardless of testing, travelers should avoid contact with people who are at risk for severe illness for 14 days.               

Please see the following SARS-CoV-2 Variants of Concern CDC websites for more information:

• CDC SARS-CoV 2 Variant Classifications and Definitions
• WHO Weekly epidemiological update on COVID-19 - 29 June 2021
• CDC COVID Data Tracker Weekly Review for June 25, 2021
• CDC Science Brief:  COVID-19 Vaccines and Vaccination, updated May 27, 2021