Even leading experts in vaccine science have been met with disbelief and ambivalence.
Dr. Gregory Polonia, 68, editor in chief of the journal Vaccine, said a loud hissing in his ears has accompanied every moment since his first shot, but that his pleas to colleagues at the Centers for Disease Control and Prevention diseases of exploring the problem phenomenon, tinnitus, had led nowhere.
He received polite responses to his numerous emails, but “I have no sense of movement,” he said.
“If they have done studies, those studies should be published,” Dr. Polonia added. In desperation to “never hear silence again”, he sought solace in meditation and his religious faith.
Dr. Buddy Creech, 50, who has led several Covid vaccine studies at Vanderbilt University, said his tinnitus and rapid heartbeat lasted about a week after each shot. “It's very similar to what I experienced during the acute phase of Covid, in March 2020,” said Dr. Creech.
Research may eventually find that most reported side effects are not related to the vaccine, he acknowledged. Many may be caused by Covid itself.
“Regardless, when our patients experience a side effect that may or may not be related to the vaccine, we owe it to them to investigate the matter as fully as possible,” Dr. Creech said.
Federal health officials say they don't believe the Covid vaccines have caused the illnesses described by patients like Mr. Barcavage, Dr. Zimmerman and Dr. France. According to the CDC, vaccines can cause transient reactions, such as swelling, fatigue and fever, but the agency has documented only four serious but rare side effects.
Two are associated with the Johnson & Johnson vaccine, which is no longer available in the United States: Guillain-Barré syndrome, a known side effect of other vaccines, including flu; and a blood clotting disorder.
The CDC also links mRNA vaccines made by Pfizer-BioNTech and Moderna to heart inflammation, or myocarditis, especially in boys and young adults. And the agency warns of anaphylaxis, or severe allergic reaction, that can occur after any vaccination.
Listening to signals
Agency scientists are monitoring large databases containing medical information on millions of Americans for patterns that might suggest a previously unknown vaccination side effect, said Dr. Demeter Daskalakis, director of the National Center for Immunization and Respiratory Diseases at CDC.
“We are in line by reporting signals that we believe are real signals and reporting them as soon as we identify them as signals,” he said. The agency's systems for monitoring vaccine safety are “pretty close” to ideal, she said.