In a recent study published in the journal Clinical Infectious Diseases, a team of researchers examined the risk factors and prevalence and impact of long coronavirus disease (COVID) among a representative sample of adults in the United States (U.S.) and reported that close to 19 million U.S. adults suffer from long COVID.
Study: The epidemiology of long COVID in US adults. Image Credit: Lightspring / Shutterstock
Long COVID, also known as post-acute sequelae of coronavirus disease 2019 (COVID-19) (PASC), comprises persistent or recurring symptoms such as fever, headaches, cognitive impairments, cardiovascular difficulties, debilitating fatigue, dyspnea, and other symptoms affecting various organ systems. The U.S. Centers for Disease Control and Prevention estimates the number of long COVID cases to be one in every five COVID-19 cases.
Studies indicate that the prevalence of long COVID is higher among women and individuals with multiple comorbidities or chronic conditions. However, a comprehensive understanding of long COVID risk factors, the impact of long COVID on the quality of life, and the effectiveness of vaccines and booster doses in protecting against long COVID are still lacking. The number of breakthrough infections has increased with the emergence of immune-evading variants such as Omicron. Therefore, determining the level of protection offered by primary and booster vaccine doses against long COVID is essential.
About the study
In the present study, the team conducted a bi-lingual (English and Spanish), cross-sectional, probability-based survey among 3,042 adults in the U.S. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection history was determined for each participant based on self-reported positive SARS-CoV-2 tests from a healthcare provider or home-rapid antigen tests or self-reported COVID-19 symptoms with evidence of close contact with a confirmed COVID-19 patient.
The survey investigated the prevalence of long COVID symptoms such as fatigue, concentration difficulties, and dyspnea lasting more than four weeks after recovering from COVID-19. The proportion of individuals who confirmed these symptoms and had COVID-19 four or more weeks before was calculated to estimate the prevalence of long COVID in the population.
Additionally, the impact of long COVID on daily activities was determined based on answers to whether and to what extent the long COVID symptoms affect the participant’s ability to perform daily activities compared to their abilities before suffering from COVID-19. The presence of comorbidities or health conditions such as cancer, chronic obstructive pulmonary disease, obesity, diabetes, cardiovascular diseases, immunodeficiency, liver disease, high blood pressure, or a recent organ transplant were also determined to understand long COVID predictors.
The results reported that 7.3% of the participants reported having long COVID symptoms, which translates to close to 19 million U.S. adults. Consistent with previous studies, the prevalence of long COVID was higher among women and individuals with comorbidities. Unvaccinated individuals, as well as vaccinated individuals who had not received booster doses also had a higher prevalence of long COVID. Adults older than 65 years had a lower prevalence of long COVID, and when compared to white non-Hispanic individuals, individuals of Black, Hispanic, and Asian/Pacific Islander races had a lower prevalence of long COVID.
Among the participants who reported long COVID symptoms, 44% had SARS-CoV-2 infections in the previous six months, 27% had SARS-CoV-2 infections six to 12 months previously, and 29% reported having a SARS-CoV-2 infection more than a year ago. In addition, all the participants with long COVID reported decreased ability to carry out daily activities. The individuals with the most recent SARS-CoV-2 infections reported the highest impact on daily activities.
Given the wide range and non-specificity of long COVID symptoms, determining the long COVID burden has proven to be complicated. Understanding the risk factors for long COVID can help formulate strategies to manage the long-lasting impacts of COVID-19. The authors discussed that many previous studies investigating the risk factors associated with long COVID had been conducted among hospitalized patients, which could over-represent individuals with comorbidities.
The present study, more representative of the U.S. adult population, reports a surprisingly lower long COVID prevalence among the elderly population. The authors believe this could be due to the increased uptake of vaccines among the older population of the U.S. and the following of disease mitigation measures such as masking and social distancing.
To summarize, this cross-sectional survey among a representative group of the adult U.S. population examined the risk factors associated with long COVID and the impact of persistent or recurring long COVID symptoms on daily activities.
The results indicated that over 18 million individuals in the United States suffer from long COVID, with a higher prevalence observed among women, individuals with comorbidities, and White persons. Unvaccinated and unboosted individuals were also more susceptible to long COVID. All individuals with long COVID symptoms reported decreased ability to carry out daily activities, but the impact of long COVID on daily life was seen to reduce with time.
- Robertson, M. M., Qasmieh, S. A., Kulkarni, S. G., Teasdale, C. A., Jones, H., McNairy, M., Borrell, L. N., & Nash, D. (2022). The epidemiology of long COVID in U.S. adults. Clinical Infectious Diseases. https://doi.org/10.1093/cid/ciac961, https://www.cell.com/cell/fulltext/S0092-8674(22)01118-7