Apr 9, 2020 - Health

CDC officials tracked large Chicago outbreak to family gatherings

Empty Michigan Avenue is seen in Chicago

An empty Michigan Avenue in Chicago. Photo: Kamil Krzaczynski/AFP via Getty Images

A case study on contact tracing in Chicago showed how one person who showed up to a family funeral with mild symptoms of the coronavirus set off a chain reaction of infections to 16 more family members, including three deaths, data from the Centers for Disease Control and Prevention show.

Why it matters: The events, which took place in February, detail powerful consequences of death and illness when family members did not social distance or avoid social gatherings. The broader Chicago community was also exposed due to these events.

By the numbers: 16 people between the ages of 5 and 86 had been infected — seven confirmed and nine probable — with three dead.

contact tracing form
Contact tracing graph from the CDC.

The state of play: The transmissions were tracked between a funeral and birthday party that were held three days apart. The person, named "Patient A1.1," was the traveling carrier with mild respiratory symptoms.

  • The person shared a takeout meal with two family members at the funeral for three hours. Both dinner hosts and a third family member who was hugged ended up infected.
  • At a birthday party days later, the person hugged guests and shared food for three hours. Seven of the nine attendees later got sick.

A few of these people were hospitalized and subsequently infected more family who came to visit them and hugged without any personal protective equipment. Others attended church and infected another person.

The bottom line: These clusters ultimately exposed the greater Chicago community and probably contributed to more cases, the CDC hypothesizes.

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