The numbers are in, and they give us some clue about what we might expect if more superspreader events happen in East Lansing as MSU students return.
A total of 192 confirmed coronavirus cases – 146 primary and 46 secondary – have now been tied to the Covid-19 superspreader event at Harper’s Restaurant and Brew Pub.
Ingham County Health Officer Linda Vail has shared with ELi the state’s epidemiological analysis. The statistics show just how quickly and far the disease spread after hundreds of people gathered in a crowded area without people wearing masks.
The data also show how difficult it can be to stop an outbreak that takes off.
Harper’s was opened from June 8-20. We now know that at least one individual who visited Harper’s began to exhibit symptoms as early as June 13.
When Harper’s shut down, about 14 cases had presented themselves. Ten times that number would ultimately present as primary cases.
By June 23 – when news of the cluster began to break – almost half of the people who would ultimately be identified in the primary case cluster were already exhibiting symptoms.
In fact, at least one person with a secondary case – believed to be caught from someone who had been at Harper’s – was showing symptoms.
For every known case by June 23, there were roughly five more people infected who were not yet referred as cases.
The first person was referred for testing on June 15, but the results were only made public June 22, giving the virus time to spread undetected.
Those who attended Harper’s passed the illness along to older adults.
People age 20-29 accounted for 89 percent of all primary cases, and individuals age 18-19 accounted for 11 percent. No one over the age of 30 contracted COVID-19 at Harper’s.
Individuals age 20-29 accounted for 54 percent of all secondary cases, but people age 50-59 accounted for nearly 20 percent of secondary cases. One person in his or her 70s was infected secondarily.
Eighteen Michigan counties ultimately saw cases linked to the Harper’s outbreak.
Many of the counties were in Mid and Southeastern Michigan, but counties as far as Manistee and Berrien were affected.
One COVID-19 positive individual linked to Harper’s traveled outside the United States. Another thirteen traveled to states outside of Michigan.
No one tied to the outbreak has been hospitalized.
But not all have yet recovered, defined by the Health Department as “alive 30 days after onset date.” Seventy-three percent of primary cases, and 61 percent of secondary cases are counted as “recovered” in the data provided.
Symptoms varied, and asymptomatic carriers were in the minority.
Asymptomatic individuals who tested positive accounted for 30 percent of primary and 20 percent of secondary cases. Some of the most common symptoms mimicked hangovers—headaches, fatigue, and body aches.
Coughs, congestion, and digestive issues also occurred, but fever was not particularly common. It was found only in 20 percent of primary cases and 40 percent of secondary.
A comparison of the primary and secondary cases suggest those in the secondary cluster may have felt sicker, as they suffered more fever, fatigue, and headaches.
The data also show breakdown by race and sex. Caucasians accounted for 87 percent of both primary and secondary cases. Women accounted for 56 percent of primary cases and 50 percent of secondary cases.
The latest science suggests that mask-wearing could have prevented at least some of these cases. Social-distancing would also have helped. Read more about the science from the Wall Street Journal.