Local health officers in the Bay Area are encouraging the public to mask up once again after seeing the second-highest surge in COVID-19 cases since the start of the pandemic. 

As of Sunday, there have been 15,512 confirmed cases with a test positivity rate of 5.06%, according to Stefan Elgstrand, spokesperson for Berkeley Mayor Jesse Arreguín. He also noted that these numbers only reflect officially recorded cases and do not include unreported cases, such as those from home test kits.

“Bay Area counties are seeing increases in reported cases, levels of virus in wastewater, and hospitalizations,” reads a city press release. “Actual case rates are higher than those reported because of widespread use of home tests.”

According to campus public health and vaccinology professor emeritus John Swartzberg, this surge in cases in the country is due to omicron, COVID-19’s most transmissible subvariant to date. In particular, Swartzberg attributed the rise to omicron’s subvariants, BA.2 and BA.2.12.1.

Swartzberg added that both subvariants are more infectious than the original omicron strain and that BA.2.12.1 is more responsible than BA.1.

“You combine a highly transmissible virus with people not wearing masks nearly to the extent they were previously and people doing things that put them at risk of getting infected in much greater numbers than they previously were,” Swartzberg said. “Adding all these things together are the major explanations to why we are seeing a surge in cases now.

Elgstrand added that while there has indeed been an increase in individuals hospitalized, the city’s successful 93% vaccination rate allows numbers to remain low. This thereby allows patients to receive appropriate resources, he noted.

While the city of Berkeley does not plan to implement a mask mandate, officials do recommend the public to mask up indoors, get tested frequently and hold large gatherings only in well-ventilated areas and outdoors, according to Elgstrand.

“I personally would have a mask on,” Swartzberg said. “Not only would I be wearing a mask, I would be wearing a good mask, N95 or KN95 or KF94, and I would be making sure that I am wearing a mask that fits well.”

Elgstrand added that businesses will have the option to implement a mask mandate.

Additionally, Swartzberg noted that while the COVID-19 pandemic’s future is unknowable, health officials observed surges in cases particularly during the past two summers. 

“Since the beginning of the pandemic, we have been chasing this virus and it has been very hard to predict what it will do,” Swartzberg said. “If history is prologued, then we are likely to encounter more variants and subvariants that will be challenging to us. But we have no idea.”