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As scientists discover more about long COVID — an array of symptoms that linger weeks and months after the initial infection has passed — governments have started to produce more reliable estimates.
The latest data, published on February 3, comes from the Office of National Statistics (ONS) in the U.K. and shows that around 1.3 million people reported having long COVID between December 2021 and January 2022.
The figure shows an increasing trend from previous months — 1.27 million at the beginning of December and 945,000 in early July.
Updates are expected to follow, but until then, here is a breakdown of what the analysis found:
According to ONS data collected from the Coronavirus (COVID-19) Infection Survey (CIS), 1.33 million people were experiencing symptoms post-infection
Furthermore, 836,000 people, almost two-thirds of those surveyed, said these symptoms limited their daily activities.
Dr. Donald J. Alcendor, associate professor of microbiology, immunology, and physiology at Meharry Medical College, and associate professor adjunct at the Vanderbilt University Medical Center, both in Nashville, TN, said the figure was surprising, as it was higher than expected for the U.K.
However, he pointed out that the nature of self-reporting could have likely skewed the results and that the duration of the symptoms would vary from one person to the next.
“[T]he diagnosis of post-COVID syndrome is not an exact science and is still controversial. Diagnosis is largely based on testing and the duration of symptoms that are mainly self-reported,” he told Medical News Today.
The most common long COVID symptoms that people reported were:
Although cognitive symptoms were not among the most common symptoms for this data set, they are also increasingly rising, added Dr. Alcendor.
Commenting on fatigue, in particular, Dr. Tutku Taşkınoğlu, clinical microbiologist and the head of the molecular biology unit at Düzen Laboratories in Turkey, told Medical News Today that it was common for some diseases to be triggered after viral infections.
“These include chronic fatigue syndrome, or myalgic encephalomyelitis, and a blood circulation disorder called postural orthostatic tachycardia syndrome (POTS), and this risk was higher [after COVID-19] than after the flu,” she said.
Dr. Taşkınoğlu underscored the importance of listening to people and that even symptoms as simple or inconspicuous as mild fatigue could be important for diagnosis.
The data found that the prevalence of long COVID was greatest in people 35–69 years.
It also found that females, people living in low-income areas, and those with a health condition or disability that limits their ability to exercise were also more likely to report having long COVID.
Dr. Taşkınoğlu said that she has also observed a difference in long COVID symptoms reported by different groups. For females and younger people, persistent headaches, abdominal symptoms, and anxiety are more common, while males and those over 65 report breathing difficulties and cognitive impairments more often.
The professions that produced the highest number of people with long COVID were social care, teaching and education, and healthcare.
Dr. Alcendor pointed out that the professions most affected by long COVID involved a lot of direct, person-to-person contact and had a higher risk of exposure.
“These jobs may involve transmissions with higher viral loads because of little or no social distancing and prolonged exposure to a person [with the virus],” he said.
He also underscored that it was not surprising to see individuals with poor social determinants on the list.
“[L]imited access to healthcare services and underlying comorbidities that go unmanaged put them at high risk for the most severe outcomes of COVID-19. We must remember that long-COVID can be mild in some people and life-changing for others,” he explained.
As the analysis focuses on self-reported long COVID, many experts are skeptical about the results.
“Self-reporting would certainly skew the results. Documentation of infection via diagnosis after testing positive and then negative is important because COVID-19 clinical presentations can vary from one person to the other and must undergo differential diagnosis to rule [out] other conditions such as a cold, flu, chronic fatigue, respiratory syncytial virus (RSV), or reinfection (breakthrough infection/post immune infection),” explained Dr. Alcendor.
One challenge in diagnosing and treating undiagnosed long COVID cases will be determining how many people have had COVID-19.
Dr. Alcendor elaborated:
“Monitoring exposure at the community level using antigen testing could provide us with insights as to how many people [had contracted the virus] and not officially diagnosed with COVID-19.”
There is also the issue of diagnosing long COVID in children. Many estimates leave that data out.
In the U.K., the first “consistent”
Dr. Alcendor said estimates in the United States were that between 10% and
Comparatively, he said the rate in the U.S. was much higher than the figure reported for the U.K.
“This could be related to awareness, vaccination, reporting, diagnosis, and the rate of infection in the U.S. compared to the U.K.,” he explained.
Dr. Taşkınoğlu said there was no clear picture about long COVID incidence in Turkey yet.
“It is not yet known exactly what percentage of people will have these symptoms months after [having acute] COVID-19,” she said.
She added that when factoring in the number of COVID-19 cases in a country, especially in places where numbers are rising like Turkey or the U.S., even 5% would mean a lot of people will be affected.
On a global level, one pre-print study estimated that around 43% of COVID-19 survivors either had or are still experiencing long-term effects after recovering from the disease.
Dr. Taşkınoğlu said that no matter what variant caused COVID-19, it could possibly lead to long COVID. She said with only 4 months into the Omicron wave, it was difficult to say what would happen in the long term.
“According to the data so far, there is no difference between Delta, Beta, or Omicron for long COVID symptoms. But most likely, the incidence of long COVID will be lower, as Omicron does not make a permanent change in the inflammatory process in the body during COVID-19 infection,” she said.
However, she pointed out one caveat with that way of thinking:
“Even if the incidence of long COVID decreases to 2-3% of cases, as the number of cases is high, the number of people experiencing long COVID will increase [proportionately],” she added.
Although reports so far suggest less severe disease in individuals who get COVID-19 with Omicron, experts reiterate that this severity can vary between people and produce fatal outcomes in individuals with underlying illnesses.
“Therefore, we may see an increase in long COVID in targeted populations with more severe diseases,” said Dr. Alcendor.
“[This will be] due to many [people contracting the virus] and the likely increase in breakthrough infections, especially among underserved populations with poor social determinants of health,” he said.
Dr. Alcendor said he expects long COVID to have more of an impact on people who experienced symptoms of COVID-19 and/or those who were in the hospital.
Dr. Taşkınoğlu agreed: “The U.K. analysis shows that the risk [of long COVID] is much lower for those who are not hospitalized.”
“The greatest impact [of long COVID] will likely be among [unvaccinated people] that acquire a primary COVID-19 infection. It is clear that being completely vaccinated for COVID-19 offers some level of protection against Omicron and will reduce the likelihood of developing long COVID if you have a breakthrough infection.”
– Dr. Donald J. Alcendor
“[They do so] by lowering the chances of contracting COVID-19 initially. Vaccinations have also been beneficial to some in that the development of a more robust immune response may complete viral clearance from a person’s system and will allow them to recover,” said Dr. Alcendor.
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