Houston is seeing an uptick in the number of BA.2 cases, with genome sequencing and wastewater testing picking up higher levels this week compared to last week.
The more contagious omicron subvariant was identified in 24 percent of patients who were sequenced at Houston Methodist, a jump from the 1 to 3 percent previously reported. BA.2 was also detected at six wastewater treatment plants on March 21 — the most recent day for which data is available — after the Houston Health Department last week said it had not been detected at any plants.
“Previously, we saw some indications of mutations consistent with BA.2 but were not confident in the determination at the time,” health department spokesman Scott Packard said in an email. “Retrospective analysis indicates BA.2 was likely in the wastewater in low levels starting in mid-to-late January.”
The recent data is the first indication of a significant rise in BA.2 in the Houston-area. Eventually, the subvariant is expected to become the dominant strain here, lining up with the nationwide rate, according to the health department.
The Centers for Disease Control and Prevention said Tuesday that BA.2 accounts for more than half of all cases in the U.S., and World Health Organization last week said it had become dominant worldwide.
It’s still unclear whether the trend will lead to another COVID surge. Some countries are seeing a rise in cases associated with the increase in BA.2, but others are not. Despite the subvariant’s rise in the United States, the country has not reported a significant uptick since omicron levels dropped in February and early March.
In Houston, the average positivity rate over the last two weeks is 1.8 percent, down from the high 30s in the early January. Wastewater testing shows an increasing viral load at nine wastewater plants, while the remaining 30 are plateaued or decreasing.
“Although BA.2 appears to be more contagious than BA.1, the good news is that countries experiencing a spike in cases are not seeing a proportionate spikes in hospitalizations,” Packard said. “That means being up to date on vaccines (initial shots plus boosters) remains highly effective against serious illness, even with BA.2.”
julian.gill@chron.com
