New long COVID studies show symptoms linger up to one year after infection

Two new long COVID studies are reporting persistent symptoms in patients up to a year after infection. A large UK study found one in three COVID-19 patients report at least one lingering symptom six months after recovery, while a more focused study from China detected nearly half of hospitalized COVID-19 patients having one symptom up to a year after discharge.

In a new study published in JAMA Network Open a team of Chinese researchers assessed 2,433 recovered COVID-19 patients, around one year after they had been discharged from hospital. Offering some of the first long-term insights into long COVID the study found 45 percent of patients report at least one symptom persisting twelve months later.

Fatigue, sweating, chest tightness, anxiety, and myalgia were the most common long-term symptoms cited by the cohort. Around a quarter of all hospitalized patients reported persistent fatigue one year later.

Old age and severe illness were linked to a higher risk of experiencing at least three long-term symptoms. However, the researchers do note their 12-month follow-up study detected lower overall rates of lingering symptoms compared to six-month long COVID studies, offering some hope that signs of long COVID may decrease over time.

“The findings provide valuable information about the long-term health outcomes of COVID-19 survivors and identify risk factors for sustained symptoms and poor respiratory health status, which is of importance with the coming of the post-COVID-19 era,” the researchers conclude.

Another new long COVID study, this time led by researchers from the University of Oxford, looked at more general characteristics of the condition in a massive cohort of 273,618 recovered subjects. Overall, nearly 37 percent of all those recovered from COVID-19 reported at least one long-term symptom lasting between three and six months beyond the acute infection.

The most commonly cited long COVID symptom in this massive cohort was anxiety or depression, reported by 15 percent. Other persistent symptoms present three to six months later include abnormal breathing (reported by 8%), abdominal symptoms (8%), chest/throat pain (6%), cognitive problems such as ‘brain fog’ (4%), fatigue (6%), and headache (5%).

“The results confirm that a significant proportion of people, of all ages, can be affected by a range of symptoms and difficulties in the six months after COVID-19 infection,” says lead on the study, Max Taquet. “These data complement findings from self-report surveys, and show that clinicians are diagnosing patients with these symptoms.”

One of the interesting findings in the Oxford study was a comparison of the prevalence of persistent long COVID symptoms to those experiencing long-term symptoms from influenza. The researchers found a number of flu cases reporting at least one symptom lingering up to six months beyond the acute infection, but long-term symptoms were much more frequent in COVID-19 cases. In fact, COVID-19 cases were 1.5 times more likely to experience long-term symptoms compared to influenza cases.

“The fact that the risk is higher after COVID-19 than after influenza suggests that their origin might, in part, directly involve infection with SARS-CoV-2 and is not just a general consequence of viral infection,” the researchers write in the study. “This might help in developing effective treatments against long-COVID.”

Over 18 months after the appearance of this novel coronavirus, these new studies add to picture of the long-term effects of infection researchers are now beginning to generate. The US government recently awarded nearly half a billion dollars to a variety of long COVID research projects and Oxford’s Paul Harrison says this kind of work is urgently necessary so we can deal with any long-term health consequences that may appear across the world over the coming years.

“Research of different kinds is urgently needed to understand why not everyone recovers rapidly and fully from COVID-19,” says Harrison. “We need to identify the mechanisms underlying the diverse symptoms that can affect survivors. This information will be essential if the long-term health consequences of COVID-19 are to be prevented or treated effectively.”

The one-year follow-up long COVID study was published in JAMA Network Open.

The Oxford long COVID study was published in PLOS Medicine.

Source: University of Oxford