Study: Many Long-Haul COVID-19 Patients Were Asymptomatic During Initial Infection


The investigators observed a near normal age distribution among patients with long-term COVID-19 symptoms, including children.

An analysis of electronic medical records in California found that 32% of individuals with long-term COVID-19 complications had asymptomatic infections, but experienced aftereffects months later.

According to the study authors, most research has focused on the 1% of COVID-19 patients who are hospitalized, although very little is known about the medium- and long-term impacts of the disease. They noted that emerging data suggest that a significant number of hospitalized patients go on to have long-term symptoms, with some studies estimating approximately 10%.

“Long-haulers represent a very significant public health concern, and there are no guidelines to address their diagnosis and management,” the study authors wrote. “Additional studies are urgently needed that focus on the physical, mental, and emotional impact of long-term COVID-19 survivors who become long-haulers.”

Persistent symptoms even months after the resolution of COVID-19 have been reported throughout the pandemic, according to the study authors. They investigated symptoms during the first 10 days of infection and at 61 days or longer after the diagnosis and used the University of California COVID Research Data Set to identify 1407 medical records.

The team developed a model to predict the likelihood of becoming a long-hauler based on patients’ symptoms. According to the study findings, 27% reported persistent symptoms after 60 days. Women were more likely to become long-haulers and all age groups were represented. Individuals between 30 and 70 years of age comprised 72% of cases. Notably, of the 34 children included in the study, 11 had long-term symptoms.

The investigators said presenting symptoms included palpitations, chronic rhinitis, dysgeusia, chills, insomnia, hyperhidrosis, anxiety, sore throat, and headache, among others. They identified 5 symptom clusters at day 61 onward: chest pain and cough; dyspnea and cough; anxiety and tachycardia; abdominal pain and nausea; and low back pain or joint pain. Non-modifiable factors, such as age, sex, and ethnicity, did not appear to be associated with belonging to a specific symptom cluster.

Although the research has not finished undergoing peer review, it is larger than many studies on long-term symptoms. Additionally, the researchers were able to obtain health and demographic information of patients throughout the state of California, giving them a large group to extrapolate from.

Based on these findings, the study authors said they observed a developing picture of long haulers potentially characterized by being Caucasian, female, and having a normal body mass index. They also noted a near normal age distribution, including children, whereas race appeared to be less predictive.


Huang Y, Pinto M, Borelli J, et al. COVID symptoms, symptom clusters, and predictors for becoming a long-hauler: Looking for clarity in the haze of the pandemic. MedRxiv; March 5, 2021. Accessed March 9, 2021.

Related Videos
Mid-section portrait of unrecognizable woman during last months of pregnancy holding her big belly gently standing against wall in blue room - Image credit: pressmaster |
Pride flags during pride event -- Image credit: ink drop |
Female Pharmacist Holding Tablet PC - Image credit: Tyler Olson |
African American male pharmacist using digital tablet during inventory in pharmacy - Image credit: sofiko14 |
palliative and hospice care/ Image Credits: © David Pereiras -
Young woman using smart phone,Social media concept. - Image credit: Urupong |
multiple myeloma clinical trial daratumumab/ Image Credits: © Dragana Gordic -
multiple myeloma clinical trial/Image Credits: © Studio Romantic -
selling mental health medication to man at pharmacy | Image Credit: Syda Productions -
Medicine tablets on counting tray with counting spatula at pharmacy | Image Credit: sutlafk -
© 2024 MJH Life Sciences

All rights reserved.