It’s too early to know for sure if one can get long COVID-19 after suffering from the omicron variant of the virus, but many doctors believe that it is possible to have long-term effects from the strain that has quickly taken hold across the globe.

Long COVID is usually diagnosed many weeks after a bout with COVID-19. Any long-lasting effects typically appear about 90 days after symptoms of the initial infection go away, Maria Van Kerkhove of the World Health Organization (WHO) said this week.

Overall, some estimates suggest more than a third of COVID-19 survivors will develop some symptoms of long COVID. Symptoms include fatigue, brain fog, shortness of breath, anxiety and other problems. The lingering illness is more likely if you’ve been hospitalized with COVID-19, but research shows it can happen even after a mild infection.

Omicron began its race around the world late last year. The variant generally causes milder illness than the delta version of the coronavirus, but has still overwhelmed hospitals.

Van Kerkhove said she hasn’t seen any research indicating that the portion of COVID-19 survivors who get long COVID will change with the omicron variant.

Dr. Linda Geng of Stanford University, who co-directs one of the many clinics specializing in long COVID, said that though she can’t say for sure, a new wave of patients is likely.

"We have to be very cautious and very careful and prepared," Geng said.

In the meantime, scientists are racing to figure out what’s behind the mysterious condition. Some theories? It may be an autoimmune disorder. Tiny microclots may be causing the disabling symptoms. Or perhaps latent viruses in the body have been reactivated.

Scientists are also looking at whether vaccines could be part of the answer. A Yale University team is studying the possibility that vaccination might reduce long COVID symptoms. And two other studies offer early evidence that being vaccinated before getting COVID-19 could help prevent the lingering illness or at least reduce its severity.