Long Covid symptoms ‘resolve in a year’ for most if infection is mild, study suggests

New research suggests mild disease does not lead to serious or chronic long-term morbidity

Long Covid symptoms should resolve within a year for most people after a mild illness, researchers suggest.

Concerns have previously been raised that many people are suffering from ongoing effects and lingering health problems after a bout of Covid, but academics now say “mild disease does not lead to serious or chronic long-term morbidity”.

A team of Israeli researchers compared data on people who had not been infected with the Covid with those who suffered a mild form of the disease – meaning they were unwell but did not require hospital care. The team also examined information on lingering symptoms after infection, both among vaccinated and unvaccinated people.

The study assessed almost two million people registered with a healthcare provider in Israel who had taken a Covid 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.

Long Covid symptoms should resolve within a year for most people after a mild illness, researchers say (Composite: Kim Mogg)

Researchers looked at information on several common symptoms that have been linked to long Covid. This included:

  • loss of taste and smell
  • breathing problems
  • concentration and memory issues – also known as ‘brain fog’
  • weakness
  • palpitations
  • dizziness

Findings showed that symptoms of long Covid “remained for several months” but were mostly resolved within a year.

Researchers 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, and children had an “increased risk of a small number of outcomes during the early phase” which generally returned to normal later on.

They also discovered that the risk of “lingering” breathing problems was more common among people who had not received a Covid jab compared with those who had.

Writing in The BMJ, the academics said: “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.

“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.”

In addition, the team 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 that more work on long Covid cases from the Omicron variant would help to clarify whether different variants carry different levels of risk long-term health effects.

The findings come after recent data from the Office for National Statistics (ONS) shows an estimated 2.1 million people in the UK were experiencing self-reported long Covid at the start of December last year. 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.

The ONS data found fatigue is the most commonly reported symptom, followed by difficulty concentrating, shortness of breath and muscle aches. A person is considered to have long Covid if symptoms continue for more than four weeks after infection.

Dr Quinton Fivelman PhD, Chief Scientific Officer at London Medical Laboratory, said the latest ONS figures paint a grim picture for long Covid sufferers, particularly with the arrival of a new highly transmissible Covid variant known as “the kraken” which has been spreading rapidly in the US, and has been detected in the UK.

He said: “The growing number of people suffering from “longer Covid” shouldn’t mask the fact that many brand-new cases of long Covid are still being reported. It’s quite wrong to believe long Covid was mainly caused by earlier variants of the virus and that new cases of the supposedly “milder” Omicron variants don’t trigger long Covid symptoms. In fact, 37% of all current cases have developed during this latest Omicron phase of the pandemic.

“It’s not hard to conclude that the higher the number of new Covid cases, the greater the likelihood of increased long Covid cases. With that in mind, we should be concerned about the number of people contracting the latest Covid XBB1.5 sub-variant, known in the US as “Kraken”.

“The problem is that this latest version, while not appearing to have any more harmful initial symptoms than previous sub-variants, does have a “growth advantage”, according to the World Health Organisation (WHO). In other words, it seems to be more easily transmissible.”