AUSTIN (KXAN) — New research out of Britain has reported a higher concentration of long COVID cases linked to last summer’s delta wave than this past winter’s omicron variant. However, local health officials say the latest subvariants open up the possibility of increased long COVID cases in the future.

Research published in The Lancet journal studied more than 56,000 adults in the United Kingdom who contracted the omicron variant as well as more than 41,000 adults in the U.K. who tested positive for the delta variant. Both symptomatic and asymptomatic patients were considered as part of the study.

Its findings revealed approximately 4.5% of studied omicron patients reported long COVID symptoms — defined as persisting symptoms four or more weeks after an initial COVID diagnosis. Among the studied patients who contracted the delta variant, the percentage of long COVID cases rose to 10.8%.

Long COVID symptoms can include cough, fatigue, body aches, brain fogginess and difficulty thinking clearly, said Dr. Desmar Walkes, the Austin-Travis County Medical Director/Health Authority. Researchers have theorized the links between the delta variant and increased long COVID cases are based on severity of illness caused by the different variants.

While omicron had higher transmissibility than delta, delta patients reported worsened symptoms, which could correlate with a higher volume of long COVID patients. However, the latest BA.4 and BA.5 omicron subvariants that are now dominant in the United States have been linked to more severe illness, opening the door for possibly worse long COVID cases in the near future.

Currently, Walkes said more research entities across the country have looked at long COVID to analyze and help develop possible treatments. Particularly, she said there’s collective concern about individual health impacts along with the effects long COVID could have on the health care system if more patients continue to emerge.

“These two new subvariants that we’re seeing in BA.4 and BA.5 seem to be causing more disease in the lung tissue than the omicron variant that we had circulating in the January, February timeframe,” she said, “so it will be interesting to see whether or not we see more long COVID with this.”