Some with ongoing effects after illness have been concerned that lingering symptoms will not disappear but academics said that “mild disease does not lead to serious or chronic long-term morbidity”.
The team of Israeli researchers compared data on people who had not been infected with the virus with people who suffered a mild form of the disease – meaning they were sick but did not require hospital care.
They also examined information on lingering symptoms after infection – both among vaccinated and unvaccinated people.
We observed that most health outcomes arising after a mild disease course remained for several months and returned to normal within the first year
The team looked at information on almost two million people registered with a healthcare provider in Israel who had taken a Covid-19 test between March 2020 and October 2021.
Data on almost 300,000 people who had a confirmed mild case of Covid was compared with the same number of people who had not tested positive for the disease.
Researchers looked at information on a number of symptoms linked to long Covid including loss of taste and smell, breathing problems, concentration and memory issues – also known as brain fog; weakness, palpitations and dizziness, among others.
They found that symptoms of long Covid “remained for several months” but mostly resolved within a year.
They also discovered that the risk of “lingering” breathing problems was more common among people who had not received a Covid-19 jab compared with those who had.
“Although the long Covid phenomenon has been feared and discussed since the beginning of the pandemic, we observed that most health outcomes arising after a mild disease course remained for several months and returned to normal within the first year,” the academics wrote in The BMJ.
“This nationwide dataset of patients with mild Covid-19 suggests that mild disease does not lead to serious or chronic long-term morbidity and adds a small continuous burden on healthcare providers.
“Importantly, the risk for lingering dyspnoea was reduced in vaccinated patients with breakthrough infection compared with unvaccinated people, while risks of all other outcomes were comparable.”
They said the largest number of long term symptoms for at least six months was found among those aged 41 to 60 compared with other age groups.
Children had an “increased risk of a small number of outcomes during the early phase” which generally returned to normal later on.
Researchers also found no difference in the course of a long Covid disease based on the strain of the virus the patient was likely to be infected with – including the original strain, the Alpha and Delta variants.
But they added more work on long Covid cases from the Omicron variant would help clarify whether different variants carry different levels of risk of long Covid.
Data from the Office for National Statistics (ONS) shows that at the start of December last year, an estimated 2.1 million people in the UK were experiencing self-reported long Covid.
Among this group, 57% reported that their symptoms had continued for at least a year and some 645,000 said they were first infected two years previously.
According to the ONS data, fatigue is the most common symptom reported, followed by difficulty concentrating, shortness of breath and muscle ache.
Long Covid is defined as symptoms continuing for more than four weeks after infection.