Studies probe unusual cases of neurologic complications, blood pressure swings, and other side effects.
COVID-19 vaccines have saved millions of lives, and the world is gearing up for a new round of boosters. But like all vaccines, those targeting the coronavirus can cause side effects in some people, including rare cases of abnormal blood clotting and heart inflammation. Another apparent complication, a debilitating suite of symptoms that resembles Long Covid, has been more elusive, its link to vaccination unclear and its diagnostic features ill-defined. But in recent months, what some call Long Vax has gained wider acceptance among doctors and scientists, and some are now working to better understand and treat its symptoms.
“You see one or two patients and you wonder if it’s a coincidence,” says Anne Louise Oaklander, a neurologist and researcher at Harvard Medical School. “But by the time you’ve seen 10, 20,” she continues, trailing off. “Where there’s smoke, there’s fire.”
Cases seem very rare—far less common than Long Covid after infection. Symptoms can include persistent headaches, severe fatigue, and abnormal heart rate and blood pressure. They appear hours, days, or weeks after vaccination and are difficult to study. But researchers and clinicians are increasingly finding some alignment with known medical conditions. One is small fiber neuropathy, a condition Oaklander studies, in which nerve damage can cause tingling or electric shock–like sensations, burning pain, and blood circulation problems. The second is a more nebulous syndrome, with symptoms sometimes triggered by small fiber neuropathy, called postural orthostatic tachycardia syndrome (POTS). It can involve muscle weakness, swings in heart rate and blood pressure, fatigue, and brain fog.