COVID can trigger tinnitus. Could the vaccines do the same?

After Gregory Poland, an internal medicine doctor at Mayo Clinic who directs its Vaccine Research Group, got his second dose of COVID vaccine in February 2021 he developed such severe and sudden ringing in his ears that he nearly veered into the next lane of traffic while driving home.

“It sounded like somebody took a whistle and out of nowhere started blowing it in my ear,” Poland said, “and it has never gone away.”

Poland, one of the foremost vaccine researchers in the world and editor in chief of the medical journal Vaccine, is one of thousands of people who believe the ringing, or tinnitus, they developed after a COVID immunization could be linked to the vaccine. The condition is a known consequence of a COVID infection.

Mounting evidence—from scientific studies and case reports—suggests that there might be a connection between COVID vaccines and rare cases of severe tinnitus. Johnson & Johnson listed it as a possible adverse effect on its U.S. COVID-19 vaccine fact sheet in February 2021. The World Health Organization advised investigating whether there’s a link between multiple COVID vaccines and tinnitus in their first newsletter of 2022. In July 2022, the European Medicines Agency added tinnitus as a possible adverse event from taking the Astra Zeneca vaccine. And Australia updated the Novavax label on January 27 to recognize tinnitus as a potential adverse event.

In the United States, more than 16,000 people have reported developing tinnitus after a COVID vaccine, some within hours and others in the following days or weeks. But, on Wednesday, Martha Sharan, a spokesperson for the Centers for Disease Control and Prevention, said the agency has determined it does “not have sufficient evidence from our surveillance to justify launching an epidemiologic study.”

“We are aware that this is occurring, but tinnitus is a very common condition that has many causes and many risk factors,” Sharan said. “We’re not dismissing it, and we'll continue to monitor it, but there's nothing that shows us that there's a safety problem between COVID-19 [vaccine] and tinnitus.”

The CDC has come under criticism from Poland and others who have asked it to study the issue. Poland said Thursday that he was disappointed with the CDC’s response. “Show me the data, what the threshold is, because what do you do with all of these reports?” Regarding the CDC’s decision not to pursue a larger study at this time, he said, “I'd like to see transparency and how the decision was made.”

But other experts express skepticism that there could be a link between a vaccine and an adverse event that occurs so quickly, including Paul Offit, director of the Vaccine Education Center at Children’s Hospital of Philadelphia and co-developer of the rotavirus vaccine.

“As a general rule, side effects associated with vaccines are associated with the immune response to the vaccine,” he said, explaining that it usually takes at least several days to occur at a level that could cause adverse effects. “What is happening one hour after you get a vaccine to cause you to have tinnitus?”

A phantom sound

Tinnitus affects more than 25 million American adults at some point, according to the American Tinnitus Association, and it’s a symptom of about 200 different disorders, from common colds to more serious conditions. It can also stem from hearing loss or taking different medications. Tinnitus can be temporary or chronic, but there’s no cure and few effective treatments exist.

Studying tinnitus is difficult and there are unique challenges to investigating a possible link.

“Unlike most any other side effect, you can’t measure it, you can’t image it, you can’t do a blood test for it, at least not currently. It’s all subjective,” Poland said. “That makes it more difficult because for clinicians—and I’m raising my hand as guilty until it happened to me—side effects that I can't see, measure, or even treat, you tend to discount and dismiss. And I think that's what's happening at the CDC level.”

The difficulties Poland raises are problematic, said Stanford otolaryngologist Konstantina M. Stankovic. “Tinnitus is a phantom sound that is generated by the brain, and the brain typically makes it when there is an injury to the inner ear,” she explained, adding that the lack of objective markers is a “huge impediment” in the field. “We have to rely on patient reports and subjective questionnaires.”

But for many people, their own experience is powerful evidence.

Robert Edmonds, a 37-year-old mechanical engineer who works for the federal government in Las Cruces, New Mexico, said the ringing in his ears developed after his second vaccine dose and was louder than driving his Ford F250 truck. He’s now taking acetazolamide—a glaucoma medication sometimes used off-label to treat other conditions including tinnitus—and, he says that has dampened it enough for a loud radio to drown it out.

“There’s no escaping it,” Edmonds said. “I’ve called it a jail inside my head. There’s nowhere to go, and you can’t put on headphones to tune it out. It’s just there all the time.”

Edmonds has spent two years raising awareness about the need for more research, including serving as administrator to a social media group with nearly 1,000 people suffering from tinnitus. He has regularly communicated with the Food and Drug Administration and the CDC’s vaccine safety division, scoured medical research, and put his own statistical chops to work (from his master’s in mechanical engineering and doctorate in astronomy).

“I’m just trying to get someone to look into this,” he said.

A Nature Medicine study of more than 150,000 people receiving care for long COVID from the Department of Veteran Affairs found tinnitus had a much greater impact on daily functioning than other sensory symptoms, including vision abnormalities and loss of smell or taste. Even with studies like this one, Edmonds says it’s difficult to convey how disruptive the condition can be. He says he knows of two people who committed suicide because their tinnitus was so crippling, one after the vaccine and one after a COVID infection.

Kathleen DesOrmeaux, a 46-year-old from Hampton Roads, Virginia, was happy to get the jab because her father had died from COVID, and she wanted to do her part in slowing the pandemic. Within 15 minutes of her first dose in March 2021, she had several bouts of vertigo, and over the next two weeks, her ears began ringing off and on until it became louder and constant.

At 67 years old, Poland judged a COVID infection was still a substantial risk, so he chose to get a booster despite developing tinnitus after the second dose. At first, his tinnitus was diminished, but it returned at a higher pitch. He recalls sitting outside that evening looking at the stars, “and tears came to my eyes when I realized I will never hear quiet again. That has a profound effect on you.”

What the CDC did

As of February 3, the Vaccine Adverse Event Reporting System (VAERS) maintained by the CDC has more than 16,354 reports of tinnitus from patients developing it after one of the COVID-19 vaccines. About 43 percent of those cases occurred within a day of vaccination. It’s one of the most common reports after already known side effects of the vaccine.

But VAERS cannot show that an adverse event is caused by a vaccine because it’s a passive monitoring system, which means anyone can report an adverse event. The reports may also be inaccurate, unverified, duplicates, or coincidental. Further, the number of reports cannot be used to establish a rate—how frequently the adverse event occurs—since it cannot account for the usual population rate of the condition.

To determine whether an adverse effect is a potential side effect of a vaccine, the CDC analyzes VAERS data. The CDC requests medical records for all individuals who file VAERS reports of “serious” adverse events. It only conducts a more detailed analysis if it detects a higher-than-expected rate.

In this instance, the CDC says it looked for tinnitus diagnoses that occurred up to 70 days after COVID vaccination in 6.6 million people’s medical records in the Vaccine Safety Datalink, a database of 13 healthcare system medical records used to examine whether a particular health condition is statistically linked to a certain vaccine.

The agency said in September that it found no evidence that tinnitus diagnoses were clustered together following vaccination but hasn’t published that analysis and declined to share the preliminary report with National Geographic.

In early October, Sharan said Tom Shimabukuro, who heads the COVID-19 vaccination safety team, wished to delay an interview with National Geographic because the CDC was conducting an additional analysis of tinnitus and hearing loss with COVID vaccines. On Thursday, nearly four months later, Sharan wrote that CDC does not currently plan to launch an epidemiologic study in VSD and again declined a National Geographic interview request with Shimabukuro.

If the CDC had found a statistically significant link to tinnitus, it could have taken steps to add an official warning to the vaccine labels. Those steps depend on what the side effect is and usually involve actions by the FDA and the vaccine manufacturer.

What does the data show?

Many studies have documented that a COVID infection can cause tinnitus. Stankovic’s research has shown the SARS-CoV-2 virus can infect specific cell types in the inner ear. But that discovery does not prove a link between COVID-19 vaccination and tinnitus.

Research on tinnitus or, more broadly, on hearing loss and COVID vaccines is sparse and contradictory, based mainly on case reports.

The only large-scale study, from September 2022, compared new cases of tinnitus after COVID-19 vaccination to new cases after flu, pneumonia, and tetanus-diphtheria-pertussis vaccinations in 2019. That study found, among nearly 2.6 million people, that approximately one in 2,600 developed a first-ever case of tinnitus within three weeks after their first COVID-19 vaccine dose. That’s lower than new tinnitus cases after the other vaccines, but higher than after a COVID-19 vaccine second dose.

The reason might be that “patients with a predisposition to vaccine-related tinnitus may be more vulnerable after the first dose than after the second dose, or that the first dose provokes an inflammatory response more likely to cause tinnitus,” the authors speculated.

The study could not, however, show a causal link between COVID-19 vaccination and tinnitus and didn’t adjust for the general population rate of tinnitus. The authors also noted that risk of tinnitus after vaccination is “likely lower than after the infection.”

Researchers from Oracle Health Sciences, a life sciences data company, analyzed VAERS data through September 2021 using a method designed to overcome one of the statistical challenges of looking for a rare possible side effect that’s common in the general population. The study, published in June 2022 and whose authors also include a current FDA employee and a retired one, “imply there is strong statistical evidence that links the mRNA vaccines with tinnitus,” lead author Rave Harpaz said. But VAERS data cannot show a causal relationship. National Geographic asked the CDC to comment on the results on September 29, 2022, but Shimabukuro said through an email from Sharan that he could not comment on a study conducted outside the agency.

The WHO report disclosed that 31,644 tinnitus cases, from 86 countries, had been reported by November 2021, more than three times as many as would be expected (8,549) based on ordinary background rates of tinnitus. A post-vaccination rate that’s higher than the background rate in a population is one of several criteria used to determine whether an adverse event might be directly caused by a vaccine, according to Poland.

A safety analysis of the Johnson & Johnson vaccine in 43,776 clinical trial participants found nine cases of tinnitus in the vaccine group and none in the placebo group in the four weeks after vaccination, but the authors didn’t calculate the statistical significance of that imbalance.

Even if the authors had calculated it, however, that imbalance could be a statistical anomaly, Offit says. Merck’s trials of his rotavirus vaccine included five cases of Kawasaki disease, a condition causing inflammation of blood vessels, in the vaccine group and none in the placebo group, he says. But that statistically significant finding disappeared when larger numbers of children received the vaccine. In fact, the same trial found five cases of arm and leg fractures in the placebo group and none in the vaccine group, but the vaccine certainly didn’t prevent fractures. “These initial observations just have to be taken with a grain of salt until you see it in large numbers,” he said.

A Pfizer spokesperson said the company has reviewed tinnitus cases and found no causal link to their vaccine. Moderna, Novavax, and AstraZeneca, did not respond to queries by the time of publication.

Where do we go from here?

Poland has been struck by the severity of his and other cases. “In 40 years of clinical practice, I never had somebody talk about [tinnitus] in those kinds of terms,” he said. For him and many others around the world, it’s been a “life-changing and never-ending consequence.” That’s why it vexes him that the CDC doesn’t currently plan to investigate it more thoroughly. His assessment: “The CDC needs to do as deep a dive into this concern as it did myocarditis. People are suffering.”

Other scientists, however, are taking note by adding tinnitus to their surveillance of adverse events. Former CDC scientist Robert Chen, who helped develop the Vaccine Safety Datalink, founded and runs the Brighton Collaboration, a group of scientists whose mission includes developing standardized definitions of adverse events from vaccines. The Brighton Collaboration added tinnitus to its adverse events of interest list in early November. The Collaboration was previously responsible for characterizing vaccine-associated myocarditis when it was identified as a rare side effect of the mRNA vaccines.

Researcher Shaowen Bao, an associate professor of neuroscience at the University of Arizona who studies neuroinflammation and tinnitus in animal models, is analyzing data from 400 people who have reported that they developed tinnitus after COVID vaccines. His research, currently unpublished, reveals patterns that he believes suggest a possible causal relationship between vaccination and tinnitus. Bao’s research has no control group and relies on a non-random sample of people, but he thinks the associations are strong enough that the CDC should look more closely at tinnitus.

Poland believes that the data offers clues to a possible link that deserves further study. One is when an adverse event’s timing occurs close to vaccination, as it did in nearly half the tinnitus cases reported in VAERS. Just because an adverse event occurs close to the time of the shot doesn’t prove it’s the cause,” Poland said, “but it is a hypothesis that deserves to be tested.”

It’s also important to look at whether the adverse event is happening under unexpected circumstances. For example, said Poland, “we don’t expect 20- and 30-year-olds to develop chronic tinnitus in the absence of known disease.”

Another consideration is whether there is a dose response—whether a symptom increases or changes with additional doses. Poland and others have noted changes in the pitch or severity of their tinnitus with a second or booster dose.

Poland emphasizes that all vaccines have some risk of side effects, and, in terms of public health, he says the good of these vaccines far outweighs the risks. But he thinks it’s critical for the public to be fully informed of possible adverse events. “You don’t get the choice of whether you’re going to get infected, whether you’re going to have a complication, or whether you’re going to have a side effect from a vaccine,” he says. All you can do is look at the balance of risks and benefits and not make fear-based decisions.

“We need to advocate that this is a serious enough hypothesis that the CDC should look into this,” Poland said. He has received messages from people from around the world whose tinnitus after COVID vaccination is so severe that they have considered taking their own lives, he says. “This is how profoundly this changes one’s quality of life.”