Alameda County, parts of which became early hot spots of COVID-19 infection in 2020, may be poised to become a hot spot once more as unvaccinated pockets of the county are seeking outbreaks of cases that are being mirrored elsewhere in the country.

County health officials announced Thursday that new cases of the coronavirus have more than doubled in the last month, reflecting the fact that there remain swaths of unvaccinated people who are still transmitting the virus to each other. Alameda County is now seeing an average of 70 new cases per day, up from 28 in early June — and the county had 88 COVID-19 patients in hospitals as of Thursday, up from 50 on June 8.

"We expect to see more COVID-19 with reopening, but the rate of this increase is concerning,” said Alameda County Health Officer Dr. Nicholas Moss in a statement. "COVID-19 is a serious threat to the health and wellness of unvaccinated residents. If you are still deciding about vaccination, continue to follow COVID safety precautions to keep from catching or spreading the virus, like wearing your mask in indoor public settings and outdoor crowded spaces."

As KPIX reports, officials said that new infections were occurring primarily among unvaccinated people in priority neighborhoods where vaccine drives are still underway. A few cases among vaccinated people have also been reported, but have mostly been mild.

County officials say they are prioritizing the creation of hyper-local vaccination sites to serve neighborhoods where vaccine rates have been low, and they are partnering with community organizations to encourage more residents to get vaccinated.

"There are many reasons why a person may have chosen not to get vaccinated yet. Many of our residents have experiences with the medical industry that make them pause when considering whether to get vaccinated," said Alameda County Public Health Director Kimi Watkins-Tartt. "My message right now to our community: COVID-19 has not gone away, and it is still making people very sick. Get vaccinated to protect yourself and your family and friends."

As the New York Times reports, similar surges are being seen in Nevada, Missouri, and Arkansas, all of which seem to be lagging behind the U.S. average for the percent of their populations who are fully vaccinated. The national rate right now is 48%, while only 42% of Nevada residents, 39.5% of Missouri residents, and 34.7% of Arkansas residents are fully vaccinated. Experts are also starting to note that the Delta variant is infecting more people who have only received one vaccination shot and failed to get a second shot yet.

The spikes point to the possibility of more mask mandates cropping up in parts of the country, and perhaps in parts of the Bay Area. Also on Thursday we learned that an outbreak at the California State Capitol building in Sacramento had infected at least nine staffers, and led to a new indoor mask mandate there.

Also as of Thursday, the CDC estimated that the Delta variant is now the dominant strain across the U.S.