Coronavirus cases have been on a steady decline recently in the Bay Area after a record-long summer surge — but for the many who caught COVID-19 this year during the successive waves caused by omicron and its subvariants, the prospects of long COVID may be a new concern.
Millions of survivors — including some who were vaccinated before becoming infected — have reported ongoing symptoms ranging from exhaustion and brain fog to racing heartbeats and loss of smell.
But has the proliferation of omicron subvariants, including the now-dominant BA.5, changed the long COVID picture?
While experts said there is still much to learn, here is what we know about long COVID at this stage in the pandemic, including how it is diagnosed, who is more susceptible to it and whether there are any treatments.
How have variants affected long COVID?
Omicron and its subvariants have been spreading for months, with each version more transmissible than the next. While some variants have more easily escaped immunity from vaccines and prior infection, omicron overall is less deadly than prior variants, experts say.
Amid this changing landscape, experts know that “long COVID hasn’t gone away” — but some evidence suggests that long COVID occurs less than with previous variants, according to Dr. Upinder Singh, one of the leads at Stanford University of the RECOVER program, a nationwide long COVID research initiative that aims to enhance recovery.
A study published in the medical journal Lancet in June tracked thousands of omicron patients from Dec. 20 through March 9, who reported persistent symptoms of long COVID at least a month after infection, and compared them to reports from patients who contracted the delta variant between June 1 to Nov. 27, 2021. It found 4.4% of omicron cases led to symptoms of long COVID, compared to 10.8% of delta cases.
“Vaccination seems to help decrease the incidence of it,” Singh said.
Phlebotomist Khaliun Gombojav prepares a BinaxNow coronavirus test card at a community testing site in San Francisco’s Mission District.
Stephen Lam/The Chronicle“But I still tell my friends and family that it’s still important to try and avoid getting acute COVID,” she added.
Mysteries remain, however.
“We still don’t understand the full physiology of why some people get it and why some don’t, why some symptoms get better,” Singh said. It’s also not known why long COVID can attack all parts of the body, from “the head to the toes.”
Dr. Steven Deeks, who leads the RECOVER program at UCSF, said while the risk of hospitalization and death with the current variants is “quite low,” especially if you are vaccinated and have a normal immune system, “one should not assume the virus is benign.”
“Many people who get omicron these days have disabling symptoms that last for weeks,” he wrote in an email. “I fear many might end up with true long COVID.”
What is the frequency of long COVID?
Put plainly, frequency estimates for long COVID are “all over the place,” Deeks said.
The CDC says the proportion of people who had COVID and will go on to develop long COVID varies, but provides some estimates based on studies:
• 13.3% at one month or longer after infection.
• 2.5% at three months or longer, based on self-reporting.
• More than 30% at 6 months among patients who were hospitalized.
Deeks said he suspects “real long COVID” occurs in about 10% to 20% of patients, “but it all depends on how the syndrome is defined.”
“The profoundly disabling version is much less common, but it occurs and remains a great reason to avoid getting infected in the first place,” he said.
The big question now, Deeks said, is whether omicron and its subvariants are associated with less risk.
“The data is certainly starting to suggest omicron will be less of a concern than the older variants, but then again more people are vaccinated or have had prior infections,” he said. “Untangling all of this will be a challenge.”
How much does vaccination reduce your risk of long COVID?
While Deeks said it is widely believed that vaccination helps cut your chances of developing long COVID, there’s no scientific consensus yet on how much.
“Nearly every study suggests those who were vaccinated and then became infected were far less likely to develop long COVID,” Deeks said — his estimate was about 50%.
But studies have varied wildly, showing a reduction in risk from 15% to 80%.
One of the most recent studies, published in late May, included 13 million participants — the largest group in such a study so far — found that vaccination reduced the risk of long COVID by about only 15%.
The additional degree of protection offered by vaccine boosters also is not clear, but Deeks said “all of the science points to the more immune you are to COVID, the better you will be long-term.”
A health care worker talks with a visitor to the Santa Clara County Valley Medical Center testing site in San Jose.
Carlos Avila Gonzalez/The ChronicleWhat are the symptoms of long COVID?
The more common symptoms of long COVID include brain fog, fatigue, headaches and those that worsen after physical or mental effort, Singh said.
Patients might be surprised that some of these symptoms may not arise until after they have recovered from their coronavirus infection, she said.
“What’s weird about long COVID compared to other illnesses is usually if you have the flu, you have a fever and get a cough, and you might have the cough for many weeks after,” she said. “With long COVID, new symptoms can develop after (infection).”
For example, a person with COVID might have a cough, fever and headache, and then recover — and subsequently might develop brain fog as their long COVID symptom.
Other long COVID symptoms can include shortness of breath, cough, heart palpitations, dizziness, sleep problems, depression and digestive issues, according to the Centers for Disease Control and Prevention.
A recent report published in The Lancet Psychiatry that looked at data from 1.5 million patients who had COVID between January 2020 and April 2022 found that while most mental health conditions related to long COVID went away over time, many cognitive and neurological impacts of the disease do not.
How is long COVID diagnosed?
Long COVID can be difficult to diagnose, Deeks said, because blood tests, routine X-rays and other diagnostic tests usually come back normal.
“For now, we diagnose long COVID simply based on symptoms,” he said. “If there is something new that can be traced back to when COVID was diagnosed, and it has persisted for a few months, then a diagnosis can be made.”
While some patients may not have particularly concerning symptoms, for others, “they can be severe and disabling,” he said.
It’s important for people experiencing symptoms to make sure they are up to date on their health maintenance and rule out other possible issues, Singh said.
“I always advise people who have ongoing symptoms or new symptoms that the best person to see is their primary care doctor,” she said. “A lot of people didn’t do regular health visits during the pandemic so they need to get integrated back into the system.”
What is the length of lingering symptoms that would qualify as long COVID?
According to Singh, experts often use two definitions: symptoms that last for more than a month, or for more than three months. She said she tends to favor the longer range, because some symptoms can be residual from the initial infection and not true long COVID.
Deeks is even more conservative with his definition.
“We typically do not say people might have long COVID until about month four,” he said.
What are the current treatment options?
At this point in the pandemic, experts said, no cure or validated treatment options exist for long COVID. For patients, the approach for now is managing the symptoms.
“Long COVID is best managed in a specialty clinic, but the waiting lists are months and in some regions over a year,” Deeks said. “Management now is focused on physical and rehabilitation therapy, which can help.”
But treatment research is underway, and trying to find what works and what does not is part of the RECOVERY studies, Singh said. The trial includes medications and non-pharmaceutical interventions such as methods to improve sleep, she said.
Is anyone at higher risk of contracting long COVID?
Early studies of long COVID showed that older women who had multiple symptoms during their COVID bout were more likely to have persisting symptoms, Singh said. But now her clinic is seeing patients who do not fit that profile.
Results from a survey of 100,000 COVID-19 survivors from personal genetics company 23andMe released in late May showed that women were twice as likely as men to have long COVID, and that people who had depression and anxiety were also more susceptible. Those with autoimmune diseases were more than twice as likely to be diagnosed with long COVID, and individuals with heart problems and diabetes had almost double the risk.
“Anyone can get long COVID,” Deeks said — though he noted that unvaccinated people “have a much higher risk.”
“Being overweight, having asthma and/or having diabetes are other risk factors,” he said. “Those who were very ill during the acute infection have the highest risk.”
In its risk categories, the CDC additionally includes people who had underlying health conditions prior to COVID.
Kellie Hwang is a San Francisco Chronicle staff writer. Email: kellie.hwang@sfchronicle.com Twitter: @KellieHwang