A recent multicountry study published in the Journal of the American Medical Association found that even mild cases of COVID-19 can have significant and long-lasting effects on people’s health.
The study examines a condition known as long COVID, or long-term symptoms of COVID-19 that persist for at least three months following initial infection by the SARS-CoV-2 virus and that continue for at least two months, with no other explanation.
The study, which analyzed data from 54 studies involving over 1 million people from 22 countries, found that an astonishing 90% of individuals with long COVID had initially experienced only mild symptoms of the disease. After developing long COVID, however, these individuals commonly reported symptoms such as fatigue, shortness of breath, and cognitive difficulties, such as brain fog, which greatly affected their daily functioning.
These symptoms were found to impact health that was as severe as the long-term effects of traumatic brain injury. The study also found that women have double the risk of men and four times the risk of children for developing long COVID.
The study looked at how many people with COVID-19 developed new clusters of long COVID symptoms and determined how their risk of developing the disease varied based on age, sex, and whether they were hospitalized for COVID-19.
The research found that individuals hospitalized for COVID-19 had a higher risk of developing long COVID and experiencing longer-lasting symptoms than those who did not require hospitalization. However, since most COVID-19 cases do not require hospitalization, a significant number of long COVID have emerged from milder cases.
The study also revealed that nearly one in seven individuals with long COVID were still experiencing symptoms a year later. It is currently unknown how many of these cases may become chronic.
Relatively little is known about long COVID, a condition that has significant human and economic costs worldwide. Our systematic, multicountry study of long COVID revealed that many individuals affected by the condition are working-age adults who may be unable to work for extended periods, resulting in loss of income, livelihoods, and housing.
Additionally, parents or caregivers living with long COVID may be unable to care for their loved ones. Long COVID is believed to contribute to people losing their jobs, disproportionately affecting women.
Per the research team behind the study, effective and affordable treatments for long COVID should be a priority for researchers and funding organizations. Currently, Long COVID clinics provide specialized care, but the treatments they offer are limited, inconsistent, and may be costly.
Long COVID is a complex and dynamic condition that researchers do not understand well. Some symptoms may disappear and then return, while new symptoms may appear. Our study focused on the three most common symptoms that affect daily functioning.
Still, the condition can include symptoms such as loss of smell and taste, insomnia, gastrointestinal problems, and headaches. However, in most cases, these additional symptoms occur along with the estimated main symptoms.
There are many unanswered questions about the causes of long COVID, such as how risk factors like smoking and high body mass index influence the likelihood of developing the condition, whether reinfection with SARS-CoV-2 changes the risk of long COVID and how the level of protection against long COVID changes over time after vaccination or booster shots.
COVID-19 variants also pose new challenges for researchers. It is known that the Omicron variant is less deadly than previous strains, and initial evidence suggests a lower risk of long COVID from the Omicron variant compared to earlier strains, but more data is needed.
Most of the individuals studied in the research were infected with the deadlier variants circulating before Omicron became dominant.
The research team will continue to build on their study of long COVID as part of the Global Burden of Disease study, which assesses deaths and disability due to all diseases and injuries in every country, to gain a better understanding of how the long-term impact of COVID-19 has changed with the emergence of the Omicron variant.
