Most long Covid symptoms go away a year after mild infection, research finds

For most Covid patients long after an initial mild infection, symptoms may persist for several months but will resolve within a year, a large study has concluded.

Analysis of the medical records of 2 million people in Israel also found those vaccinated had a lower risk of breathing difficulties – the most common lingering symptom after a mild infection.

Report results in the BMJthe researchers also said that of the small proportion of children who had persistent symptoms after infection with Covid-19, the vast majority recovered.

The latest figures from the Office for National Statistics released on January 5 show that around 2.1 million people in the UK, or 3.3% of the population, suffered from long self-reported Covid symptoms for more than four weeks .

This includes 1.9 million people (87%) who believe they had Covid at least 12 weeks ago, 1.2 million (57%) at least a year ago and 645,000 (30%) at least two years ago.

Israeli analysis of health records between March 2020 and October 1, 2021 examined longer than long Covid conditions in infected and matched uninfected individuals, as well as comparison of vaccination status and Covid variants.

Anyone admitted to hospital with more severe illness was excluded from the study and other chronic conditions and socioeconomic status were taken into account.

Mild Covid-19 infection was associated with a 4.5 times higher risk of loss of smell and taste at the start of the classified period of 30 to 180 days after infection and with an almost 3 times higher risk at the end of the period, defined as 180 -360 days.

The symptoms with the highest burden during the early and late phases were weakness and difficulty breathingthe researchers said.

Breathing difficulties remained persistent throughout the first year post-infection in the 19-40, 41-60 and over 60 age groups.

The patterns identified in the study were similar across wild-type, Alpha, and Delta Covid-19 variants.

But the analysis also showed that vaccinated people who were infected had a lower risk of breathing difficulties compared to unvaccinated infected patients although a similar risk of other symptoms.

“Our study suggests that patients with mild Covid-19 are at risk for a small number of health problems and most of these resolve within a year of diagnosis,” they concluded.

“Importantly, the risk of persistent dyspnea was reduced in vaccinated patients with breakthrough infection compared to unvaccinated individuals,” they added.

Professor Peter Openshaw, professor of experimental medicine at Imperial College London, said the size of the study meant researchers could look at changes in symptom prevalence over time and the effects of other factors on persistent symptoms.

He noted that the loss of smell tended to resolve around nine months, but the changes in concentration and memory tended to be more persistent.

“Persistent shortness of breath tended to resolve over time and vaccination was associated with a lower risk of developing it.

“The general message that symptoms get better over time is encouraging, but it can take around a year for some symptoms to go away.

“The study adds to the evidence that outcomes are improved by vaccination, even though vaccines do not prevent viral transmission very well.”