FRESNO, California (KSEE) — As the 4th of July celebrations are about to get underway in the Central Valley, the delta variant of COVID-19 is causing major concerns.

There’s also confusion over mask-wearing.

Jon Zweifler, M.D. with Fresno County’s Department of Public Health is reminding everyone that COVID-19 is a respiratory virus that is transmitted through air particles when an infected person coughs, sings or even speaks.

During a live conversation on KSEE24 Sunrise, Zweifler said that as people gather for the Fourth of July holiday, it’s important to remember that COVID-19 is still a threat to both vaccinated and unvaccinated people.

“So even though the vaccine is extremely effective, it is not 100 percent effective,” said Dr. Zweifler. “So I think it is important for people to remember what are those high-risk situations. Being indoors, being in a crowded setting, being around others who are not vaccinated or not wearing masks. It’s a higher-risk environment. If you are outdoors you should be pretty safe but indoors, in those crowded settings, you are at high risk and in those settings a mask makes a lot of sense.”

He also added that while Fresno County is reporting low levels of COVID-19, that could change when the more transmissible delta variant begins to spread.

He says California as a whole has experienced about a 20 percent increase in cases the last few weeks because of the delta variant.

“In Fresno County we are seeing very low levels, which I think reflects that the delta variant has not yet really shown up here,” Zweifler says. “I think when it does show up […] we will start to see rising case rates.”

Dr. Zweifler adds getting vaccinated reduces your chance of being infected by 10 to 20 times.