How much can HIV genetic sequence data add to an outbreak investigation beyond tracing people's partners?

Details

The Massachusetts Department of Public Health and the Centers for Disease Control and Prevention collaborated to characterize a human immunodeficiency virus (HIV) outbreak in northeastern Massachusetts and prevent further transmission. The study assessed how HIV sequence data contributed to defining the outbreak.

This outbreak investigation analyzed HIV surveillance and partner services data to understand social and molecular links within the outbreak. Cases were defined as HIV infections diagnosed during 2015–2018 among people who inject drugs with connections to northeastern Massachusetts, or HIV infections among other people named as partners of a case or whose HIV polymerase sequence linked to another case, regardless of diagnosis date or geography.

Of 184 cases, 65 (35%) were first identified as part of the outbreak through molecular analysis. Twenty-nine cases outside northeastern Massachusetts were molecularly linked to the outbreak. Large molecular clusters containing 75, 28, and 11 people were identified. Among 161 named partners, 106 had HIV; of those, 40 (38%) were diagnosed through partner services.

The researchers concluded that HIV sequence data increased the case count by 55% and expanded the geographic scope of the outbreak. HIV sequence data and partner services data each identified cases that the other method would not have identified, maximizing prevention and care opportunities for people with HIV and their partners.