The flu continues to decline in South Carolina as the season draws to a close, but health authorities are reporting some cases of influenza B in recent weeks in a season predominated by influenza A.
Since the season began, 85 percent of the flu reported has been influenza A H1N1, also called swine flu, according to the state Department of Health and Environmental Control. Nearly 13 percent of the rest of the cases were another A strain.
Only about 2 percent have been influenza B, DHEC reports.
While flu activity is considered low overall, a wave of influenza B virus is affecting parts of the country, according to the U.S. Centers for Disease Control and Prevention.
“We have seen an increase in influenza B over the past four to six weeks,” said Dr. Bill Kelly, chief infectious disease specialist with Greenville Health System. “The overall numbers, however, are vastly decreased from the December peak.”
Kelly said influenza B often emerges at the end of flu season causing a smattering of cases. But they are usually milder and slower-spreading than influenza A, he said.
While a wave of influenza B may seem unusual because there haven’t been many cases of it this season, the current case count doesn’t constitute a spike, said DHEC spokesman Jim Beasley.
“It’s not unusual to see a second wave of influenza in which a different strain circulates predominantly. We’ve seen this in previous seasons,” he said.
“We need to remember that the flu season is not over,” he added. “Although the unofficial end of flu season is the end of May, we know the flu has the ability to spread throughout the year.”
CDC says it’s possible significant flu activity could continue into May and still recommends people get a flu shot if they haven’t yet. This year’s vaccine includes the H1N1, the H3N2 — both A strains — and Type B, Beasley said.
In the week ending April 12, 19 hospitalizations and no deaths were reported, according to DHEC. But there have been 1,832 hospitalizations and 76 deaths — 30 of them in the Upstate — since the season began on Sept. 29.