WALNUT CREEK (KPIX) — Just weeks after things seemed to be getting back to normal as COVID case numbers dropped, the CDC on Tuesday did an about face with their masking guidance, recommending vaccinated people wear masks indoors.

“Anyone who is fully vaccinated can participate in indoor or outdoor activities, large or small, without wearing a mask or physical distancing,” CDC Director Dr. Rochelle Walensky said back on May 13th. Those who had already received the vaccine rejoiced, with many shedding their masks.

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But most people never heard the rest of Dr. Walensky’s message that day.

“This past year has shown us that this virus can be unpredictable,” she said. “So if things get worse, there is always the chance that we may need to make changes to these recommendations.”

That’s what happened Tuesday. The CDC reversed its recommendation and now says even vaccinated people should wear masks when indoors.

The reluctance of some to get the vaccine has opened the door to the Delta variant, leading to cases skyrocketing across the nation.

“In health care, we’re used to guidelines shifting. But what COVID is teaching us is that this is really unprecedented,” said said UCSF Infectious Disease Professor Dr. Peter Chin-Hong. “We never expected Delta to be like this. Two months ago, we were in a completely different landscape than where we are right now.”

Dr. Chin-Hong said not only is the Delta variant easier to catch, it also causes vaccinated people to carry more of the virus in their noses and mouths, making them more likely to spread the disease to others. Previously, it was believed the vaccines prevented people from growing enough of the virus for it to be passed on.

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“In fact, that’s what many people believe is the driving force for the new CDC guidance on masking amongst the vaccinated,” he said.

No one knows yet what state or local mandates may come in the wake of the new CDC guidelines, but it’s clear it will be a challenge to get people wearing masks again, now that they haven’t been wearing them for weeks.

“I just thought it was unnecessary,” said Arezo Habibi Mison in downtown Walnut Creek. “And I know that’s not good and a lot of people don’t like to hear that. But I feel like a lot of people in my age group, they’re not going to be wearing masks.”

But Hercules resident Doris Gurganious thinks there will be a price to pay for that.

“I think it’s going to be around for a long time because everyone is not following whatever rules and regulations is passed down by the CDC,” she said. “And some people are really too excited about being out and not valuing the life of them and their families.”

The CDC says the new mask guidance applies to vaccinated people when indoors in areas where there is “substantial or high levels of community spread.”

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Currently, all Bay Area counties fit that description.