"Research of different kinds is urgently needed to understand why not everyone recovers rapidly and fully from Covid-19. We need to identify the mechanisms underlying the diverse symptoms that can affect survivors," Harrison, who headed the study, said in a statement.
For the study, the team investigated long-Covid in over 2,70,000 people recovering from Covid-19 infection, using data from the US-based TriNetX electronic health record network.
The study reported on how commonly nine core long-Covid symptoms were diagnosed and how this rate compared to people recovering from influenza.
The nine core long-Covid symptoms, occurring 90-180 days after Covid-19 was diagnosed, comprise -- abnormal breathing - 8 percent, abdominal symptoms - 8 percent, anxiety/depression - 15 percent, chest/throat pain - 6 percent, cognitive problems ('brain fog') - 4 percent, fatigue - 6 percent, headache - 5 percent, myalgia (muscle pain) - 1.5 percent, other pain - 7 percent, any of the above features - 37 percent.
Higher rates were seen if the whole 1-180 day period after Covid-19 infection was included.