What are the patterns of symptoms and risk factors for Long COVID among SARS-CoV-2 infected individuals?

In a recent study posted to the medRxiv* preprint server, researchers explored the indicators of long coronavirus disease 2019 (COVID-19) symptoms.

Background

After acute infection, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection-related symptoms such as weariness, memory/concentration difficulties ("brain fog"), and breathlessness may linger.

Cohort studies that need in-person participation could exclude individuals unable to undertake study visits or who live far from research sites; therefore, survey-based approaches, especially those that utilize pre-infection information, may aid in the scientific community's knowledge related to long COVID and its preceding factors.

About the study

In the present study, researchers determined whether sociodemographic variables, lifestyles, medical history before COVID-19 infection, or acute COVID-19 features are linked with long COVID.

The COVID-19 Citizen Science (CCS) project is an online study design for which participant recruitment commenced on 26 March 2020. Participants must be 18 years or older, possess an Android or iOS smartphone, consent to participating in English, and be granted consent to enroll for a Eureka Research Platform account.

Participants respond to baseline, everyday, weekly, and monthly questions after expressing electronic consent. For this analysis, the team included data acquired between 26 March 2020 and 18 May 2022. For longitudinal symptomatic evaluation, those who did not have a COVID-19 positive test were estimated and compared to persons without SARS-CoV-2 infection.

In January 2022 and May 2022, participants who had a positive COVID-19 test over 30 days before were presented with a cross-sectional questionnaire regarding Long COVID Symptoms. Using an unvalidated tool, the survey inquired about the existence, duration, and intensity of Long COVID symptoms. A Likert scale was used to determine the severity of each reported symptom: "How severe do you believe these symptoms were?" In addition, the survey inquired about healthcare utilization and days lost from work or school owing to COVID symptoms.

The team also categorized the questionnaires for every subject as per period concerning the positive SARS-CoV-2 test into 30 to 60 days and zero to 30 days before infection, and zero to 30 days, 30 to 90 days, 90 to 180 days, 180 to 365 days, and over 365 days after infection. For every period, the number of respondents that averaged one or more symptoms as well as the mean number of symptoms noted as per long COVID status, was added up among cross-sectional survey respondents, non-respondents who were infected with SARS-CoV-2, and uninfected persons.

Results

A total of 13,305 subjects were diagnosed with COVID-19 over 30 days before the survey as of 18 May 2022. Among these, 1,480 people replied to the questionnaire about Long COVID symptoms, while 476 had long COVID symptoms. In comparison to the nonrespondents, individuals who responded to the survey had a higher chance to have tested positive during the SARS-CoV-2 Omicron wave and a lower chance to have tested positive in the initial infection wave.

Additionally, survey respondents were more likely to have received their COVID-19 vaccination before infection and to have experienced comparatively more acute symptoms. The median period since the initial SARS-CoV-2 positive test for individuals who did and did not have long COVID symptoms was 360 days and 129 days, respectively.

Fatigue was the most prevalent symptom of long COVID, as indicated by 230 of 476 patients. In addition to shortness of breath, disorientation, headache, and changed smell or taste were all common symptoms. A minority of individuals experienced a minimum of one symptom as severe or extremely severe. Almost  219 of 476 subjects reported healthcare contact regarding long COVID. Furthermore, 124 subjects reported skipping work or school because of long COVID, with 57 individuals missing one to five days, 24 missing six to 10 days, and 43 missing 11 days or more.

There was a correlation between the amount of acute COVID-19 symptoms noted at initial infection and the prevalence of long COVID symptoms, with probabilities 1.3 times higher with every additional acute symptom. Notably, the variant wave was also connected with the prevalence of long COVID symptoms, with subsequent wave participants having a lesser chance of exhibiting long COVID symptoms, although they had a shorter follow-up duration among symptomatic individuals. Long COVID symptoms were not significantly linked with vaccination status. Depression and financial insecurity were correlated with Long COVID after further adjustment for depression, anxiety, and financial instability.

Conclusion

The study findings showed that long COVID symptoms displayed high prevalence and frequently persisted. Long COVID was associated with more symptoms due to acute infection, financial stress, lower socioeconomic position, and pre-COVID depression. Lastly, long COVID symptoms were less likely among those infected with novel SARS-CoV-2 variants.

*Important notice

medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.

Written by

Bhavana Kunkalikar

Bhavana Kunkalikar is a medical writer based in Goa, India. Her academic background is in Pharmaceutical sciences and she holds a Bachelor's degree in Pharmacy. Her educational background allowed her to foster an interest in anatomical and physiological sciences. Her college project work based on ‘The manifestations and causes of sickle cell anemia’ formed the stepping stone to a life-long fascination with human pathophysiology.