Two forms of Covid – long and acute – differ distinctly, according to scientists, who say their findings will help improve diagnosis and treatment.
Symptoms characteristic of acute Covid included loss of taste and smell, fatigue, cough, shortness of breath, and muscle pains or aches, whereas typical symptoms of long Covid, defined as continuing for more than 12 weeks and not explained by an alternative diagnosis, included fatigue, shortness of breath, muscle pain or aches, difficulty concentrating, and chest tightness.
Researchers at University College London said their findings, which collated information from more than 42,000 people from nine national population studies, is the strongest data on the subject to date. It looked at multiple studies across different areas in the UK, and involved a wide range of people.
“Building the evidence base regarding typical long Covid symptoms will improve diagnosis of this condition and the ability to elicit underlying biological mechanisms, leading to better patient access to treatment and services,” the authors said. Their work was published in the European Journal of Epidemiology.
The unique aspect of the study, as well as its size, is the “inclusion of symptom data from individuals who have never had Covid-19”, UCL’s Dr Richard Silverwood told i.
“Many of the previously reported Covid-19 and long Covid symptoms may also occur in the absence of Covid-19, so without an understanding of the background prevalence of these symptoms in the population it is difficult to determine to what extent symptoms are occurring as a consequence of Covid-19/long Covid specifically. Because we have access to this information we are able to identify which symptoms have the most ‘excess’ prevalence relative to the background levels.”
Last year, another group of scientists said they had identified three types of long Covid, each with a unique sets of symptoms. The largest group was those with neurological symptoms such as fatigue and brain fog, with separate groups for those suffering breathing problems and symptoms including changes to hair and skin.
However, UCL researchers said the information collected did not provide compelling evidence for different “types” of long Covid.
Vaccination status was not considered by the researchers and, given the timing of symptom data collection relative to the vaccination programme rollout from January 2021, would not have been relevant for many of the studies they analysed, but could be of interest in future research, the UCL team said.
The data was also collected prior to the emergence and dominance of the Omicron variant in the UK, meaning it could be difficult to compare to the current UK circumstances.
An estimated 2.1 million people in the UK (3.3 per cent of the population) were experiencing self-reported long Covid as of early December 2022, latest figures from the Office for National Statistics show.
There is recent (encouraging) evidence that long Covid symptoms from mild infections resolve within a year rather than leading to chronic health problems among the vast majority of people, according to a study conducted in Israel and published in the journal BMJ.
John Moore, Professor of Microbiology and Immunology at Weill Cornell Medical College in New York, said: “Many of these cases resolved certainly within a year, which is not great – I’m not trying to minimise this. But there’s increasing indications that for most people, it’s not for life, which is a good thing.”
The UCL studies included information on between 16 and 28 symptoms reported across 15 months of the pandemic, from July 2020 to September 2021. Of the large group, some 9,277 people reported having Covid-19.
Some symptoms such as a runny nose or sneezing were not more common in those with or without Covid, or those reporting long Covid, suggesting they are not Covid-specific.