OTTAWA -- It doesn’t take much for COVID-19 to spread, and it can start with an outdoor gathering.

That’s the message from Ottawa Public Health this week, sharing a real-world example of what community transmission of COVID-19 looks like.

The example started with an outdoor barbecue in a park. It ended with more than 100 people having to self-isolate for two weeks and get tested for the virus.

“You can see how a group of 40, a couple of people ill, quickly can lead to 105 people having to stay home and multiple more people testing positive,” medical officer of health Dr. Vera Etches told the city’s board of health Monday night.”

Of the 40 people at the outdoor gathering, two people went on to develop symptoms of COVID-19, Etches said. One of those people went on to have close contacts in their household, who tested positive.

But the other person with symptoms had a far wider impact.

“It really had a significant impact in terms of two workplace outbreaks,” Etches said.

One of those outbreaks was in a child care setting, where there was transmission among staff. Then two other children became symptomatic and went to two different schools on two different buses.

That led to parents having to miss work and kids having to miss school, after extensive contact tracing efforts by public health officials.

“There were 105 high-risk contacts who then needed to self-isolate for 14 days and go and get tested,” Etches said.

The party ultimately led to 27 positive COVID-19 cases.

Earlier this month, Etches shared an example at city council of 10 people who attended a cottage party. One person with symptoms quickly became 40 people who tested positive for COVID-19 within nine days.

The province has since instituted limits on private gatherings of 10 people indoors and 25 people outdoors.

Under these rules, the 40-person park BBQ would no longer be allowed, but the cottage party would be.