As severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus responsible for coronavirus disease 2019 (COVID-19), has continued to infect millions worldwide, increasing complaints of chronic symptoms have been reported among those who recover from this disease.
These symptoms were eventually recognized as a condition known as “long covid”, post-acute sequelae of COVID-19 (PASC) or post-covid condition. A new study under review in the journal Scientific Reports and available now on Research Square’s preprint server* suggests that these complaints may not be extremely common among patients with COVID-19 compared to the general population.
Study: Development of Covid-19 complaints or prevalent in general? Image credit: Kateryna Onyshchuk / Shutterstock.com
Introduction
PASC causes a wide range of symptoms linked to many organs and is associated with varying severity. Little is still known about this disease, its prevalence, risk factors and prognosis.
Shortness of breath, cough, brain fog, loss of concentration and fatigue are the main complaints of PASC. Neurological symptoms also include prolonged disturbances of smell and taste. Previous studies published in several different countries have found that some of these symptoms were more common in people who had recovered from COVID-19.
The overlap between several complaints often associated with PASC and their development over time in most patients with mild COVID-19 has been debated. Given that the vast majority of patients with COVID-19 will experience mild symptoms and not require hospitalization, the need to identify the risk of PASC in this group is clear, especially since mildly advanced infections are common among vaccinated individuals.
About the study
The current study aims to understand whether PASC actually exists and how it changes over time. In addition, researchers from the Norwegian Institute of Public Health and Lund University examined how similar symptoms evolve over time in non-COVID-19 patients.
Neurological, pulmonary and general complaints were the main focus of this study, as these are the most common features reported by PASC patients.
The data used in the current study were obtained from the Norwegian Emergency Preparedness Register of COVID-19 tests in Norway since the start of the pandemic and excluded hospitalized patients. This also provided demographic and vaccination data.
All participants were between 18 and 70 years of age and were classified as having evidence of COVID-19 or not between August 1, 2020 and August 1, 2021. No participants had a diagnosis code for none of the PASC complaints included six months prior to the COVID-19 Test until the start of the testing week if the test was taken.
This allowed complaints or queries related to the test rather than pre-test or those that were part of other tests ordered before a specialist consultation.
Patients were categorized as positive for COVID-19, those who tested negative, and those not tested.
Results of the study
More than 76,000 people tested positive for COVID-19, while more than 1.1 million tested negative and more than one million were not tested. Of those who tested positive for COVID-19, 0.05% died and 0.2% moved out of the area. Of the negatives, 0.06% died and 0.1% emigrated to Norway.
Percentage-adjusted prevalence and 95% confidence interval for different post-covid complaints at baseline, 2-, 4-, and 6-month follow-up for persons testing positive and negative for SARS-CoV-2. Missing circles, triangles, or squares indicate that there are no observations for the group in question. The prevalence of pulmonary+neurological+general complaints could not be represented due to very few observations.
People who tested positive for COVID-19 were more likely to be younger and healthier and not vaccinated more often than the other two groups. These people also had a higher number of medical consultations for general illnesses between 2017-19; however, this increased rate of hospital visits was not reflected when neurologic, pulmonary, and general complaints were assessed.
The prevalence of unique complaints increased over two months from baseline. However, when pulmonary and general complaints occurred together, their prevalence was reduced by two to six months. Neurological complaints were lower at baseline and increased at a slower rate.
Pulmonary and general complaints were more common in people who recovered from COVID-19 than in the other two groups, especially two months after their initial diagnosis. This difference decreased at four and six months. Differences between groups were smaller for neurological complaints and showed little or no differences over time up to six months from the test date.
At the latter time, 50-250 more people per 10,000 patients with COVID-19 could be diagnosed with pulmonary or general complaints compared to those who were not diagnosed with COVID-19. The difference for neurological complaints was only five to ten people per 10,000. If untested individuals were excluded, direct comparison differences were lower.
Overlapping complaints were uncommon in the COVID-19 group, although their complaints were generally higher.
Implications
The study results indicate a small increase in the prevalence of PASC-like complaints after recovery from COVID-19 of 5-250 per 10,000 people compared to those who tested negative or the untested population. Most of these complaints occurred either in relation to breathing, fatigue or neurological symptoms in isolation rather than as a syndrome.
Therefore, complaints that are often considered typical post-covid complaints may also be naturally prevalent complaints, regardless of the initial illness.”
Even with a small increase in the frequency of these complaints after COVID-19, the burden on the healthcare system may be high due to the sheer magnitude of the cases of COVID-19.
When combined with previous studies, the study results may indicate that both mild COVID-19 and severe influenza predispose to a small increase in lung-related symptoms and fatigue six months after infection in these patients. However, the World Health Organization (WHO) has defined PASC as very rare as a result of its low prevalence.
Further research based on patient reports or more sensitive clinical data will be needed to validate these findings and determine how other mild viral respiratory infections correlate in terms of long-term sequelae. The impact of booster vaccination doses on PASC, as well as risk factors for post-covid complaints, remains to be determined.
*Important news
Research Square publishes preliminary scientific reports that are not peer-reviewed and therefore should not be considered conclusive, guide clinical practice or health-related behavior, or be treated as established information.