As she recovers from an illness that she believes was likely Covid-19, Greta Thunberg is imploring others with mild flu-like symptoms to stay home.

The teen climate activist shared on Instagram that she had been staying indoors for the past two weeks. After returning to Sweden from a trip around central Europe, she said, she and her father isolated in a borrowed apartment away from her mum and sister.

“Around ten days ago I started feeling some symptoms, exactly the same time as my father – who traveled with me from Brussels,” Thunberg wrote.

“I was feeling tired, had shivers, a sore throat and coughed. My dad experienced the same symptoms, but much more intense and with a fever.”

In Sweden, authorities have shifted from testing all possible coronavirus cases to only those in vulnerable groups. According to Sweden’s public health agency, they had adjusted their strategy to prioritise resources for those at high risk of severe illness. Anyone else experiencing cold or flu-like symptoms is told to simply stay home.

“I have therefore not been tested for Covid-19, but it’s extremely likely that I’ve had it, given the combined symptoms and circumstances,” Thunberg said.

By the time of her Instagram post Tuesday, Thunberg said she had basically recovered, but she highlighted the biggest takeaway from her experience.

“I almost didn’t feel ill. My last cold was much worse than this! Had it not been for someone else having the virus simultaneously I might not even have suspected anything. Then I would just have thought I was feeling unusually tired with a bit of a cough.”

The fact that many young, healthy people may be asymptomatic or experience only very mild symptoms and may go on to pass it unknowingly to others is what makes the situation so much more dangerous, Thunberg wrote.

She urged her Instagram followers to consider the effects of their actions.

“We who don’t belong to a risk group have an enormous responsibility, our actions can be the difference between life and death for many others.”

Her advice: Follow the advice of experts and local authorities, stay home, and always take care of those around you and those in need.