One in eight people who get infected with COVID-19 develop at least one symptom of long COVID, according to a new study.

Since the start of the pandemic in 2020, more than half a billion coronavirus cases have been recorded worldwide, leading to rising concern about the lasting symptoms of long COVID in people infected by the disease.

Since almost none of existing research compared sufferers of long COVID to people who never got infected, it’s possible that some of the health problems patients experienced were not caused by the virus.

A comprehensive study published in The Lancet recently revealed that of those with COVID, over 21% had developed at least one new or severely increased symptom just three to five months after getting initially infected with the virus.

However, nearly 9% of a control group that did not have COVID also reported a similar increase, suggesting that 12.7% of those with COVID – equivalent to one in eight – suffered from long-term symptoms.

For the study, the researchers asked more than 76,400 adults in the Netherlands to fill out an online questionnaire on 23 of the most common symptoms of long COVID. Between March 2020 and August 2021, each participant had to answer the questionnaires 24 times.

The research also recorded symptoms before and after infection, finding that the most common symptoms of long COVID included chest pain, loss of taste and smell, breathing difficulties, muscle pain, and general fatigue.

Study author Aranka Ballering of the Dutch University of Groningen called long COVID “an urgent problem with a mounting human toll.”

"By looking at symptoms in an uninfected control group and in individuals both before and after SARS-CoV-2 infection, we were able to account for symptoms which may have been a result of non-infectious disease health aspects of the pandemic, such as stress caused by restrictions and uncertainty," Ballering added.

The study authors noted that emerging data from other studies showed people who have been vaccinated or infected with the omicron variant have a lower risk of long COVID. However, more research was needed to substantiate such findings.