COVID-19: Community Transmission of SARS-CoV-2 at Two Family Gatherings in Chicago

COVID-19: Community Transmission of SARS-CoV-2 at Two Family Gatherings – Chicago. Spencer EA, Heneghan C.

Published on July 2, 2020

Reference Ghinai I, Woods S, Ritger KA, et al. Community Transmission of SARS-CoV-2 at Two Family Gatherings - Chicago, Illinois, February-March 2020. MMWR Morb Mortal Wkly Rep. 2020;69(15):446-450. 2020
Study type
Country USA
Setting Family gathering
Funding Details Non reported
Transmission mode Person to person, Close contact
Exposures Family gatherings, funeral and birthday party

Bottom Line

Gatherings likely to involve physical greetings and prolonged close proximity probably increase transmission of SARS-CoV-2.

Evidence Summary

A cluster of 16 cases of confirmed or probable COVID-19 were identified, including three deaths. 

Epidemiological data gathered suggested that these cases resulted from transmission of SARS-CoV-2 at two family gatherings: a funeral and a birthday party. 

What did they do?

In February and March 2020, the Chicago Department of Public Health (CDPH) investigated a large, multifamily cluster of COVID-19. 

Patients with confirmed COVID-19 and their close contacts were interviewed to better understand nonhousehold, community transmission of SARS-CoV-2. 

Contact tracing interviews were conducted with patients with confirmed COVID-19 using a structured questionnaire designed to identify the date of symptom onset and any person with whom the patient had close contact since that date. The type of contact and setting in which the contact occurred were recorded. Close contacts of patients with confirmed or probable COVID-19 were interviewed and enrolled in active symptom monitoring.

Patients were classified as having confirmed COVID-19 if SARS-CoV-2 was detected by real-time reverse transcription-polymerase chain reaction testing of a nasopharyngeal or oropharyngeal specimen. 

Patients were classified as having probable COVID-19 if they developed new symptoms of fever, cough, or shortness of breath within 14 days of contact with a patient with confirmed or probable COVID-19 but did not undergo laboratory testing.

Study reliability

Lack of laboratory testing for “probable” cases means some probable COVID-19 patients might have instead experienced unrelated illnesses. Phylogenetic data, which could confirm presumed epidemiologic linkages, were unavailable.

Clearly defined setting Demographic characteristics described Follow-up length was sufficient Transmission outcomes assessed Main biases are taken into consideration
Yes Yes Unclear Yes Unclear

What else should I consider?

Transmission may have been through these gatherings but may also have occurred elsewhere.

About the authors

Carl Heneghan

Carl is Professor of EBM & Director of CEBM at the University of Oxford. He is also a GP and tweets @carlheneghan. He has an active interest in discovering the truth behind health research findings

Elizabeth Spencer

Dr Elizabeth Spencer; MMedSci, PhD. Epidemiologist, Nuffield Department for Primary Care Health Sciences, University of Oxford.