The big idea
Even mild cases of COVID-19 can have major and long-lasting effects on people’s health. That’s one of the key findings from our recent multinational study on long COVID-19 – or long COVID – published recently in the Journal of the American Medical Association.
Long-term COVID is defined as the continuation or development of symptoms three months after the initial infection with SARS-CoV-2, the virus that causes COVID-19. These symptoms persist for at least two months after onset without any other explanation.
We found that an astonishing 90% of people living with prolonged COVID initially had only mild illness with COVID-19. After developing prolonged COVID, however, the typical person experiences symptoms including fatigue, shortness of breath, and cognitive problems such as brain fog—or a combination of these—that affect daily functioning. These symptoms have as severe a health impact as the long-term effects of traumatic brain injury. Our study also found that women are at twice the risk of men and four times the risk of children to develop prolonged COVID.
We analyzed data from 54 studies reporting on more than 1 million people from 22 countries who had symptoms of COVID-19. We counted how many people with COVID-19 developed clusters of new long-term symptoms of COVID-19 and determined how their risk of developing the disease varied by their age, sex, and whether they had been hospitalized for COVID-19.
We found that patients who were hospitalized for COVID-19 had a greater risk of developing long-lasting COVID—and of longer-lasting symptoms—compared to people who were not hospitalized. However, because the majority of cases of COVID-19 do not require hospitalization, many more cases of prolonged COVID have occurred from these milder cases despite their lower risk. Among all people with long-term COVID, our study found that almost one in seven were still experiencing these symptoms a year later, and researchers do not yet know how many of these cases may become chronic.
Why it matters
Compared to COVID-19, relatively little is known about long-term COVID.
Our systematic, multinational analysis of this condition yielded findings that illuminate the potentially high human and economic costs of prolonged COVID worldwide. Many people living with the condition are working-age adults. Being unable to work for many months can cause people to lose their income, livelihood and housing. For parents or caregivers living long with COVID, the condition can leave them unable to care for their loved ones.
We believe, based on the widespread and severity of the long-term COVID, that it is preventing people from working and therefore contributing to labor shortages. The long COVID may also be a factor in how people losing their jobs have disproportionately affected women.
We believe that finding effective and affordable treatments for people living with prolonged COVID should be a priority for researchers and research funders. Long-standing COVID clinics have opened to provide specialized care, but the treatments they offer are limited, inconsistent and can be expensive.
What next
Long-term COVID is a complex and dynamic condition – some symptoms disappear, then return and new symptoms appear. But researchers still don’t know why.
Although our study focused on the three most common symptoms associated with prolonged COVID that affect daily functioning, the condition can also include symptoms such as loss of smell and taste, insomnia, gastrointestinal problems, and headaches, among others. But in most cases, these additional symptoms appear along with the main symptoms for which we made assessments.
There are many unanswered questions about what predisposes people to prolonged COVID. For example, how do different risk factors, including smoking and a high body mass index, affect how likely people are to develop the disease? Does re-infection with SARS-CoV-2 alter the risk of persistent COVID? Furthermore, it is not clear how protection against prolonged COVID changes over time after a person has been vaccinated or boosted against COVID-19.
The COVID-19 variants also present new puzzles. Researchers know that the omicron variant is less lethal than previous strains. Initial evidence suggests a lower risk of long-lasting COVID from omicron compared to earlier strains, but much more data is needed.
Most of the people we studied were infected with the more lethal variants that circulated before omicron became dominant. We will continue to build on our long-term COVID research as part of the Global Burden of Disease study – which makes estimates of deaths and disability from all diseases and injuries in every country in the world – to get a clearer picture of how the long-term toll of COVID-19s have changed since the arrival of omicron.
Sarah Wolf Hanson, Lead Researcher on Global Health Metrics, University of Washington and Theo Voss, Professor of Health Metrics, University of Washington
This article is republished from The Conversation under a Creative Commons license. Read the original article.
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