In-Depth: BA.5 reinfections send California's COVID wave soaring

COVID-19 coronavirus
Posted at 4:37 PM, Jul 19, 2022
and last updated 2022-07-19 21:38:55-04

SAN DIEGO (KGTV) – Wastewater monitoring in the Bay Area suggests the ongoing surge of BA.5 has now eclipsed the levels of transmission seen in that area during the massive Omicron surge over the winter.

So far, San Diego’s monitoring stations show we’re still about one-fourth of the way to last winter’s peak, but testing reveals gradually rising levels of virus.

“What this tell us, it’s not going to be over in at least two more weeks,” said Dr. William Tseng of Kaiser Permanente. “We’re still not there.”

BA.5 continues to spread fast because it’s able to easily reinfect people. In June, San Diego County recorded 3,122 reinfections, nearly double the figure from May, according to data from the county’s Health and Human Services agency.

“This variant does escape the vaccine immunity – against infection – not against hospitalization or death. But from an infection standpoint and transmission, you can still get reinfected,” Tseng said.

In some cases, there are reports of people getting re-infected with BA.5 in as little as one month after a previous bout with COVID. But UC San Diego’s Dr. Robert Schooley points out, one month ago, wastewater testing showed more than 90 percent of the circulating virus was not BA.5.

“Most of the people who are getting BA.5 now are ones who had old-fashioned Omicron,” he said. “The immunity we develop from prior infection or from vaccination isn't directly as relevant to the BA.5 as to other variants. It does protect you from severe disease, but it's not as good at preventing breakthrough infections.”

Doctors believe BA.5 is super infectious for two main reasons. Today’s vaccines are based on a version of the virus from 2019, so they produce antibodies that aren’t an ideal shape. Once BA.5 enters a cell, research shows it can make many more copies of itself, allowing the virus to rapidly gain a foothold.

CDC guidelines say infected people can leave quarantine after five days if they haven’t had a fever in at least 24 hours. They must wear a mask for five days after that.

“How do you spread BA.5? Use the [CDC’s] isolation 5-day guidance,” tweeted Dr. Eric Topol of Scripps Research Institute.

Last month, research in the New England Journal of Medicine showed that people infected with original Omicron, BA.1, stayed infectious for eight days on average. Since BA.5 produces more viral copies than BA.1, doctors theorize it will take the body longer to clear the subvariant, potentially extending the length of contagiousness.