The Centers for Disease Control and Prevention (CDC) released a study last Tuesday that found one in five adults under 65 and one in four adults over 65 may develop long Covid. People in both groups had twice the risk of uninfected people of developing respiratory symptoms and lung problems, including pulmonary embolism. Individuals in the older age group were at greater risk of developing kidney failure, Type 2 diabetes, neurological conditions, and mental health issues.
Shortly after the Covid-19 pandemic started, the National Institutes of Health (NIH) began looking into why some patients suffer from long-lasting health problems. Researchers knew from previous infectious outbreaks that some individuals are more likely to have enduring symptoms.
The results of the NIH study were published in the Annals of Internal Medicine last week. It compared 189 patients who had Covid-19 with 120 similar individuals who didn’t get sick. The volunteers were put through over 130 tests for any signs their vital organs were damaged, the virus was still hiding in their bodies, or their immune systems were malfunctioning. In addition, the scientists went through their medical records, checking for anything that might indicate a higher susceptibility of persistent health problems, like fatigue, headaches, and shortness of breath.
According to Dr. Michael Sneller, an infectious disease specialist who led the study, “An extensive medical evaluation failed to reveal a cause for these persistent symptoms in most cases. We were not able to find evidence of the virus persisting or hiding out in the body. We also did not find evidence that the immune system was overactive or malfunctioning in a way that would produce injury to major organs in the body.”
Dr. Aluko Hope of the Oregon Health & Science University says the results are a “valuable contribution” to understanding long Covid by providing a baseline of patients’ health early on in their disease. However, he notes the study didn’t focus enough on understanding the fatigue many long Covid patients experience when they try to exercise or otherwise exert themselves. “Without a fuller understanding of pathophysiology and disease course, we must not allow normal objective tests to negate our patients’ subjective experiences,” he says.
Dr. Sneller agrees. Not only are the scientists continuing to study the first patients, but they’re also examining hundreds of others, including conducting additional tests. “We are continuing the analysis looking for any evidence of autoimmunity or anything else,” he says. “This paper is not the end of it — it’s just the beginning.”
While we don’t know what predisposes someone to develop long Covid yet, a study from Northwestern University found that the symptoms last, on average, about 15 months after first falling ill. Researchers selected participants who never needed hospitalization because their initial symptoms were mild.
Last week, the study was published in the peer-reviewed journal Annals of Clinical and Translational Neurology. It found no significant change in the frequency of patients experiencing symptoms, such as brain fog, numbness/tingling, headache, dizziness, blurred vision, tinnitus (ringing in the ears), and fatigue, between their first appointments and six to nine months later. While the loss of taste and smell decreased over time, heart rate and blood pressure variation and gastrointestinal symptoms increased at the follow-up.
The Northwestern study also found that 77% of the participants had been vaccinated against the coronavirus. The shots didn’t appear to have a positive or negative impact on whether a person experienced symptoms of long Covid. According to Dr. Igor Koralnik, chief of neuro-infectious diseases at Northwestern Medicine, “There is a neutral effect of vaccination. It didn’t cure long covid. It didn’t make long covid worse.”
Northwestern researchers acknowledge that the study has limitations since in only included 52 patients. Also, the individuals had to have visited the Northwestern clinic and chosen to participate in the study.
A paper published in Nature Medicine backs up these findings. It’s part of a series of studies by the Department of Veterans Affairs involving 33,940 people and specifically looked at individuals who had a breakthrough infection after vaccination. The data shows that vaccination significantly reduces the risk of death or serious illness, like lung and blood clot disorders. However, there wasn’t a difference between the vaccinated and unvaccinated when it came to longer-term risks of neurological issues, gastrointestinal symptoms, kidney failure, and other conditions.
The Veterans Affairs study is currently the most extensive peer-reviewed analysis in the U.S. on long Covid based on medical records. It looked at patients who either had two doses of the Moderna or Pfizer BioNTech vaccines, or one dose of the Johnson & Johnson vaccine. Not included was the impact of booster shots nor how different variants may change the risk of long Covid. The study took place when alpha, delta, and prior variants were at high levels and didn’t cover the period when the omicron variant and its subvariants began circulating.
There’s a lot left to be learned about long Covid and its impacts, but we are starting to see more and more data come forth, which should help guide the path forward.