The surprise predictors for Long Covid – not what you thought!
While SARS-CoV-2 is usually thought of as an acute disease, we now know that some people who have had acute COVID experience a variety of post-acute health problems long after their disease onset. This experience of long-term persistent symptoms has been termed “long COVID”, and those who suffer from it "long haulers". Acute COVID typically lasts 3 weeks, but long COVID can last weeks or months. Studies have reported widely varying prevalence levels of long COVID.
In December 2020, the Office for National Statistics (ONS) in the UK estimated the prevalence of long COVID in the U.K. from a survey of 8,193 non-hospitalized and non-institutionalized respondents who ever tested positive for COVID during the survey follow-up and found that 10% exhibited symptoms lasting longer than 12 weeks. The period of twelve weeks has become important, as most definitions use this as the minimum length of time for a case to be defined as long COVID.
People who have COVID-19 can experience symptoms for months after this cut-off point. Studies on long COVID in the population lack representative samples and longitudinal data focusing on new-onset symptoms occurring with COVID while accounting for pre-infection symptoms. In a recent study from the USA, about 23% of the sample experienced new-onset symptoms during infection which lasted for more than 12 weeks, and thus can be considered as having long COVID. The most common persistent new-onset symptoms among those included in the study were
- headache (22%),
- runny or stuffy nose (19%),
- abdominal discomfort (18%),
- fatigue (17%), and
- diarrhea (13%).
The single pre-existing health condition that predicted long COVID was obesity, which increased risk of long COVID by a factor of 5.44, so you are more than five times more likely to suffer from long COVID if you are obese than if you are not.
In addition, those who experienced the following symptoms during COVID infection significantly increased the chances of them developing long COVID:
- hair loss increased the risk of developing long COVID by a factor of 7,
- headache increased the risk of developing long COVID by a factor of 3.37,
- sore throat increased the risk of developing long COVID by a factor of 3.56.
Contrary to popular opinion, the odds of developing long COVID among people who experienced chest congestion during acute COVID were significantly lower. Significantly, severe COVID or hospitalisation with acute COVID were not predictors for long COVID.
None of the existing chronic health conditions, bar obesity, were significantly related to developing long COVID.
Risk was unrelated to age, gender, race/ethnicity, education, current smoking status, or comorbid chronic conditions, barring obesity.
So, COVID long haulers are more likely to experience hair loss, headache, and sore throat at the time of infection compared to their counterparts whose symptoms reduce more quickly. Also, those who are obese are at higher risk of experiencing new-onset persistent symptoms.