Why Vaccines May Be Helping Some With Long COVID

As more people get vaccinated, a surprise discovery has been that the vaccines seem to provide relief for some patients with what’s being called “long COVID” (when symptoms linger for weeks or even months). Persistent and unpredictable, the symptoms of long COVID can include chronic cough, chest pain, shortness of breath, memory and sleep problems, and in the most severe cases, even organ damage.

Doctors don’t know a lot about what causes long-term COVID-19 symptoms, and there are many questions still to be answered about the reported improvements seen with the vaccines: Why might the vaccine help some people? Are some vaccines better at this than others? Could a tool designed for prevention also serve as a treatment?

Akiko Iwasaki, PhD, professor of immunobiology at Yale School of Medicine, and a major contributor to the existing body of COVID-19 research, is among those now focused on generating hard data on vaccinated "long-haulers" to help answer these questions. She is currently working with other scientists to launch what she predicts will be a large collaborative study at Yale. Key members include Harlan Krumholz, MD; Wade Schulz, MD, PhD; Aaron Ring, MD, PhD; and Charles Dela Cruz, MD, PhD.

They will be recruiting people with long-term symptoms who have not been vaccinated, so they can collect blood and saliva samples. The researchers will then follow up to collect additional samples after vaccination, so they can compare the immune responses in these long-haulers and correlate them with their symptom changes.

There are a number of questions to be answered, Iwasaki says.

The Centers for Disease Control and Prevention (CDC) uses the term post-COVID conditions to describe health issues that persist more than four weeks after a person has been infected with COVID-19. While older people and those with compromised immune systems are more likely to become long-haulers, the condition has also been seen in people who had mild cases and those who had never gone to the hospital for COVID-19 treatment. The latter group has commonly included younger women.

There could be a variety of reasons why these people continue to have symptoms: For instance, they could be the result of residual infection or an autoimmune reaction. While there are multi-year studies underway to investigate post-COVID-19 conditions, much of the information available so far is based on reports from the patients themselves. 

As many as 30 to 40% of those who get the vaccine have reported improvements to their symptoms. “I’ve heard from people who say they no longer have ‘brain fog,’ their gastrointestinal problems have gone away, or they stopped suffering from the shortness of breath they’ve been living with since being diagnosed with COVID-19,” says Iwasaki.

It’s possible that the vaccine is helping the immune system fight off residual virus lingering in their bodies and clearing these remnants away, says Iwasaki. Or the vaccine could be stopping a harmful immune response. Or it might serve to reset the immune system. At this point, researchers can only hypothesize. There is a lot to learn about how the vaccine works in long-haulers, which is why Iwasaki and her collaborators are pursuing this research.

Iwasaki recommends long-haulers get vaccinated like everyone else. So far, reports show about 10-15% percent of long-haulers feel worse after vaccination, and there are a number who don’t notice any change at all. But even if the vaccine isn’t helping everyone with long-term symptoms, it seems to be making a number of them feel better.  

In addition, vaccines will protect long-haulers from reinfection by the virus. “That’s exciting news, and I want to learn more about why that’s happening. There are currently no treatments for long-haulers so any insight would be helpful,” Iwasaki says.

[Visit Yale Medicine's Vaccine Content Center for more stories on COVID-19 vaccines.]