Most symptoms or conditions that develop after a mild COVID-19 infection linger for several months but return to normal within a year, finds a large study published by BMJ.
These findings suggest that, although the long-COVID-19 phenomenon has been feared and discussed since the beginning of the pandemic, the vast majority of mild disease cases do not suffer serious or chronic long-term illness, say the researchers.
Long-COVID-19 is defined as symptoms persisting or new symptoms appearing more than four weeks after initial infection. In March 2022, an estimated 1.5 million people in the UK (2.4% of the population) reported long-COVID-19 symptoms – mainly fatigue, shortness of breath, loss of smell, loss of taste, and difficulty concentrating.
But the clinical effects of long-COVID-19 one year after mild infection and their association with age, sex, COVID-19 variants, and vaccination status are still unclear. To address this, researchers compared the health of uninfected individuals with those who had recovered from mild COVID-19 for a year after infection.
They used electronic records of a large public healthcare organization, in which almost 2 million members were tested for COVID-19 between March 2020 and October 2021. Over 70 long-COVID-19 conditions were analyzed in a group of infected and matched uninfected members (average age 25 years; 51% female).
They compared conditions in unvaccinated people, with and without COVID-19 infection, controlling for age, sex and covid-19 variants, during early (30-180 days) and late (180-360 days) time periods after infection. Conditions in vaccinated versus unvaccinated people with COVID-19 were also compared over the same time periods.
Male and female patients showed minor differences, and children had fewer outcomes than adults during the early phase of COVID-19, which mostly resolved in the late period. In addition, vaccinated people were at lower risk of breathing difficulties – the most common effect to develop after mild infection – compared with unvaccinated people.