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The Research Brief is a short summary of interesting academic work.
The big idea
Even mild COVID-19 cases can have major and long-lasting effects on people’s health. That’s one of the key findings of our recent multi-country study of long-term COVID-19 — or long-term COVID — recently published in the Journal of the American Medical Association.
Long COVID is defined as the continuation or development of symptoms three months after the initial infection of SARS-CoV-2, the virus that causes COVID-19. These symptoms last for at least two months after onset with no other explanation.
We found that as many as 90 percent of people with long-term COVID-19 initially experienced only mild illness. However, after developing long-term COVID, the typical person experienced symptoms such as fatigue, shortness of breath, and cognitive problems such as brain fog — or a combination of these — that affected day-to-day functioning. These symptoms had as serious an impact on health as the long-term effects of traumatic brain injury. Our study also found that women are twice as likely as men and four times as likely as children to develop long-term COVID.
We analyzed data from 54 studies reporting on more than 1 million people from 22 countries who had experienced symptoms of COVID-19. We counted how many people with COVID-19 developed clusters of new long-term COVID symptoms and determined how their risk of developing the disease varied based on their age, gender and whether they had been hospitalized for COVID-19.
We found that patients who were hospitalized for COVID-19 were at greater risk of developing long-term COVID and long-term symptoms than people who were not hospitalized. However, because the vast majority of COVID-19 cases do not require hospitalization, many more cases of long-term COVID have emerged from these milder cases, despite their lower risk. Our research found that of all people with long-term COVID, nearly one in seven were still experiencing these symptoms a year later, and researchers don’t yet know how many of these cases may become chronic.
Lung COVID can affect almost every organ in the body.
Why it matters
Compared to COVID-19, relatively little is known about long COVID.
Our systematic, multi-country analysis of this condition produced findings that illuminate the potentially high human and economic costs of prolonged COVID around the world. Many people living with the condition are working-age adults. If people are unable to work for months, people can lose their income, their livelihoods and their housing. For parents or caregivers living with long-term COVID, the condition can leave them unable to care for their loved ones.
We think, based on the pervasiveness and severity of long-term COVID, it is preventing people from working and therefore contributing to labor shortages. Prolonged COVID could also be a factor in how people losing their jobs have disproportionately affected women.
We believe that finding effective and affordable treatments for people with long-term COVID should be a priority for researchers and research funders. COVID clinics have long opened to provide specialized care, but the treatments they offer are limited, inconsistent and can be costly.
What’s next
Long COVID is a complex and dynamic condition: some symptoms disappear, then come back and new symptoms appear. But researchers don’t yet know why.
While our research focused on the three most common symptoms associated with long-term COVID that affect day-to-day functioning, the condition can also include symptoms such as loss of smell and taste, insomnia, gastrointestinal issues, and headaches, among others. But in most cases, these side symptoms occur along with the main symptoms for which we have made estimates.
There are many unanswered questions about what predisposes people to long-term COVID. For example, how do various risk factors, including smoking and a high body-mass index, affect people’s chances of developing the condition? Does reinfection with SARS-CoV-2 change the risk for long-term COVID? It is also unclear how protection against long-term COVID-19 changes over time after a person has been vaccinated or boosted against COVID-19.
COVID-19 variants also present new puzzles. Researchers know that the omicron variant is less lethal than previous strains. Initial evidence shows a lower risk of lung COVID from omicron compared to previous strains, but much more data is needed.
Most of the people we studied were infected with the deadlier variants that were circulating before omicron became dominant. We will build on our research into long-term COVID as part of the Global Burden of Disease study – which estimates deaths and disability from all illnesses and injuries in every country in the world – to get a clearer picture of how The long-term toll of COVID-19 shifted once Omicron arrived.
Sarah Wulf Hanson is Principal Investigator of Global Health Metrics, University of Washington and Theo Vos is Professor of Health Metric Sciences, University of Washington
This article is republished from The Conversation under a Creative Commons license. Read the original article.
