With cases of COVID-19 on the rise in Chicago and around the country, Mayor Lori Lightfoot renewed a plea for residents to get vaccinated — and asked everyone to wear masks indoors, even when among vaccinated people. But the mayor insisted she’s not yet ready to mandate masks or increase other restrictions, saying the city would remain open — and cautious — amid the surge of the delta variant.

Lightfoot was joined at a rare Sunday press conference by Chicago Department of Public Health Commissioner Allison Arwady, who said she believed a surge was on the way, but added she didn’t think it would be as deadly or high as previous surges because of how much of the population has been vaccinated.

“I expect we will see a surge, but it may be more like what we saw in our third mini surge in April, where most of those cases were in people who were unvaccinated,” Arwady said. “We have no goal or current plans to close down Chicago again. But we need people, please, once again to step up.”

Lightfoot too defended once again allowing the mega music festival Lollapalooza to go on, saying the festival organizers did a good job of checking for vaccinations and turning away those who couldn’t prove they’d been inoculated or were COVID-free. However, she admonished the crowds of concert goers who boarded the CTA this weekend without masks.

“Do not get on public transportation…without a mask. Do not,” she said. “You’re putting yourself at risk, you’re putting everybody else at risk…I hope that we don’t have to get to a point where we’re writing people tickets, but if we need to, to get the word out and to make sure that people are compliant, we absolutely will.”

Lightfoot and Arwady’s comments come as every county in the Chicago metro region is now considered by the Centers for Disease Control and Prevention to be areas with “substantial” transmission of COVID-19, triggering a recommendation that all people, regardless of vaccination status, wear masks in indoor public spaces.

The comments also come on the heels of new information leaked in the past week from the CDC that the delta variant circulating in the country has lead to high viral loads even among vaccinated people. Still, hospitalizations and deaths among vaccinated people are still extremely low.

Chicago began seeing Friday an average of more than 200 new COVID-19 cases a day, and an average of 1 death per day. But Arwady emphasized that’s much lower than the hundreds of deaths the city saw each week at the height of past surges. She attributed that to vaccinations.

Arwady said that “99.9%” of vaccinated people in Chicago have not gotten COVID-19, and emphasized that it’s likely that the virus will be with us for some time, which includes occasional surges of cases.

“Where we are right now in Chicago is honestly better than a typical flu season,” she said. “What we see is that people who are able to get vaccinated…be much less likely to be hospitalized or die.”

Still, Lightfoot reminded residents that they can get at-home vaccination and urged vaccinations in particular for six city ZIP codes that are below 50% vaccinations — South Deering, Englewood, South Shore, Auburn Gresham, Roseland and Austin.

“The delta variant is real. It is vicious and it attacks those that are not vaccinated. Don’t take that risk, when the vaccine is readily available,” Lightfoot said. “We will bring the vaccine to your home. All you have to do is call, and sign up.”

Residents can go to zocdoc.com/vaccine or call 312-746-4835 to sign up for a free in-home vaccination, officials said.

Angela Rozas O’Toole is an editor for government and politics at WBEZ. Follow her @angelarozas.