A mixed-methods exploratory cross-sectional survey study design was used to find out about vaccinations taken and possible side effects.

This study was conducted by the Union of Finnish Ménière Association sending a questionnaire by email to the members of the Union of Finnish Ménière Association, who had a registered email address. The Union of Finnish Ménière Association is a charitable organization consisting of eight regional Ménière Associations and the main aim of the Union is to coordinate and organize peer support for Ménière patients offered by the local associations. The Union administers centrally the above-mentioned member register, and the register adheres to the GDPR (General Data Protection Regulation) of the EU. The data collection was completely voluntary and non-invasive and therefore by Finnish law did not require formal ethical committee approval, as confirmed by the Finnish law authorities (ETENE). The study was approved on 9 September 2021 by the internal ethics board of the Union of Finnish Ménière Association and was carried out according to the principles expressed in the Declaration of Helsinki. The anonymized data set was provided to the research team.

Participants provided online written, informed consent for participation by confirming they understood how their data would be used and what the study entailed.

The survey questions were developed jointly by the study authors (IP, NP) and FMF (Finnish Ménière Federation). The survey included demographic questions (i.e., gender, age, and presence of vertigo prior to the vaccination), vaccination related questions (i.e., number of COVID-19 vaccinations received, type and date of the vaccinations), and adverse vaccination effects (i.e., vertigo, imbalance, drop attacks [Tumarkin’s otolithic Crisis]), hearing loss, aural fullness, tinnitus, sinus symptoms, headaches, arm pain and/or fever). Respondents were asked to report symptoms that appeared within three weeks after vaccinations. There was also the option to include descriptions and provide more information regarding the symptoms experienced. All the questions, except the descriptions were mandatory, and participants could not continue unless they answered prior questions. This may have reduced the numbers completing the full questionnaire.

The eligibility criteria included adults aged 18 years or older who provided written electronic informed consent. The survey was distributed via email to members of the FMF who were above 18 years, who were assumed to have a history of Ménière’s disease, and who had a registered email address, which accounts for 75% of their members. The survey was lunched on October 10 ^th, 2021 and closed on October 28 ^th, 2021. Reporting bias was minimized by allowing anonymous responses and carefully wording to be non-leading where possible.

All analyses were completed in the Statistical Package for Social Sciences (SPSS) version 26.0. Significance was set to p ≤ .05, two-tailed. All the data was, thus using completer’s analysis. As all the questions were mandatory, there was no missing data, except for comment boxes.

Post-hoc tests were Bonferroni corrected for multiple comparisons. Continuous data are expressed as mean and standard deviation (SD). Categorical data are shown as percentages and frequencies. Initial analysis involved all the respondents (n = 333). To evaluate the vaccination effect, those who did not have the vaccination were removed (n = 6).

Subgroups were compared for those not reporting post-vaccination adverse effects and those reporting general post-vaccination effects (e.g., fever, arm pain, headaches) and those reporting vertigo-related effects (e.g., vertigo, falls, imbalance). The independent-samples t-test were used for continuous variables and the Chi-squared test for categorical variables together with adjusted standardized residual values during post-hoc testing. Spearman’s rho correlations (categorical variables) were used to estimate the strength of association between reporting vertigo-related problems and other post-vaccination-related effects. Correlation strength was categorized as very weak (.00 to .19) weak (.20 to .39), moderate (.40 to .59), strong (.60 to.79) and very strong (.80 to 1.0). Following this, hierarchical linear multiple regression models were performed with vertigo-related problems as the dependent variable and other post-vaccination-related effects as predictor variables. Due to the categorical data dummy variables were used. Qualitative data from the open questions were analyzed separately using inductive content analysis to supplement the quantitative analyses.

A total of 333 participants responded to the survey from an estimated 550 participants (60% response rate). The mean age was 63 years (SD: 11 years) with an unequal gender divide with 81% being female and 19% being male as seen in Table 1, partly representing the higher incidence of Ménière’s Disease in women. ¹⁸ There were 31% reporting no history of vertigo prior to the vaccination and 69% reporting either constant (6%), episodic (47%) or a mixture of constant and episodic vertigo (16%). Those reporting no vertigo had a higher mean age (65 SD: 10 years) than those reporting constant (63 SD: 13 years) or episodic vertigo (62 SD: 12 years) or a mixture of constant and episodic vertigo (60 SD: 11 years). This may represent the progression of the Ménière’s disease that those that are older were in the later stages and hence having fewer symptoms. This indicated a significant relationship between age and type of vertigo reported ( r = -.19, p = 0.002). Of those responding, 327 (98%) had the first, 313 (94%) had the second and 12 (4%) had the third vaccination as seen in Figure 1. The majority were vaccinated with Comirnaty (Pfizer/BioNTech) (69%) followed by Oxford- Astra Zeneca (15%) and then Moderna (8%) vaccinations.

Of the 327 who were vaccinated, 203 (62%) reported no vaccination adverse effects and 124 (38%) reported post-vaccination adverse effects. The most common adverse effect was injection site tenderness (38%), followed by arm pain (21%), fever (15%) and headaches (15%) as seen in Figure 2. Although differences in symptom reporting was observed, such as less fever reported by those with Comirnaty (10%) compared to those Astra Zeneca (30%) and Moderna (33%) no significant correlations were found between the symptom reported and type of vaccination received. From the open-ended responses (see supplementary information S2) most of these symptoms were short lived, expected and mild as described by these example responses: “Mild pain at the injection site that disappeared the next day,” “Mild fever the next day after the first vaccination,” and “A headache that lasted 1 day.” Post-vaccination tinnitus and vertigo (both 7%) were the most frequently reported audiovestibular-related symptoms, followed by aural fullness (6%) and hearing loss (4%).

Table 1 compares those reporting and not reporting general post-vaccination adverse effects. There were no significant associations regarding those having effects or not, based on the type of vaccination received. Age differences were present as those having vaccination effects were significantly older. Gender differences were also seen as significantly fewer females (33%) had adverse effects compared with those with no effect (67%). Significantly more males (55%) had effects compared to those with no effects (45%). The time of vaccination had no effect, except for the second vaccination, significantly fewer respondents vaccinated in April-June experienced adverse effects (55%) compared with those without effects in this period (45%). Spearman’s correlations investigated the effect of the vaccination type and the presence of symptoms. The only weak positive correlation was for local arm pain being higher for those with the Moderna injection (although this is a smaller sample: 10 not having pain and 17 having pain). Those receiving Astra Zeneca and Moderna were less likely to report injection pain.

Of the 327 who were vaccinated, 281 (86%) reported no vertigo, imbalance, swaying or drop attacks and 46 (14%) reported at least one vertigo-related post-vaccination symptom as seen in Table 2. Of these 23 (7%) reported one symptom and 23 (7%) reported two or more symptoms. There were no gender effects and no differences found related to the type of vaccination received. Those who were younger were significantly more likely to report vertigo and imbalance post-vaccination. There were also significant differences based on the presence of pre-vaccination vertigo-related problems as those reporting previous pre-vaccination vertigo were more likely to have post-vaccination vertigo. The strength of this relationship was a small positive relationship ( r = .16, p = .005). When looking at the group reporting vertigo as the largest vestibular complaint (n = 23), there were no significant difference between this group and those not reporting vertigo as seen in the last column of Table 2.

There was a positive relationship between experiencing post-vaccination vertigo and experiencing post-vaccination tinnitus, hearing loss, aural fullness, headaches, and rhinitis as seen in Table 3. The correlation was strong for tinnitus, moderate for hearing loss and aural fullness and weak for headaches and rhinitis. Hierarchical linear multiple regression analysis was carried out to investigate the ability of the presence of these adverse effects to predict the presence of post-vaccination vertigo (see Table 3). All the available effects were used in the model. The model significantly improved the ability to post-vaccination vertigo and imbalance [ F(8, 318) = 34.21, p = 0.001*] and 46% (Adjusted R ² = 0.63) of the variance was explained by the presence of these symptoms. Removing the non-significant variables did not improve the model. The variables making significant predictors regarding the presence of post-vaccination vertigo and imbalance were tinnitus ( β = .50, p < 0.001), aural fullness ( β = .19, p < 0.001), rhinitis ( β = .14, p = 0.003) as seen in Table 3.

From the open-ended responses it was very difficult to identify if some participants were describing vaccination-related effects or general pre-vaccination effects due to vague comments such as “Hearing problems in my right ear,” Constant feeling of pressure,” or “headaches.” A summary of the number of open-ended responses for each symptom and information regarding the onset, duration and vaccination dosage where available is available in Underlying data. The onset of vertigo and unsteadiness was between 12 hours to two and a half weeks post-vaccination. Where reported, the duration was between a few hours to two weeks. Effects were reported for either of the vaccination doses and at times both the first and second doses. Some patients reported that they felt that their symptoms were exacerbated by the stress during the pandemic and not necessarily the vaccination.

There were numerous limitations that should be considered when interpreting the results. Firstly, there is possible sampling bias as those responding to the survey may be patients more likely to have had post-vaccination effects. The sample was not well balanced due to an unequal gender divide, which may have affected results, although Ménière’s disease is known to be more prevalent in females. ¹⁸ The survey could have been improved to ask specific questions regarding the onset, duration and dosage linked to the adverse effects. Vertigo-related problems are also frequently experienced during cardiac problems. Post-vaccination vertigo could be associated with cardiovascular problems ²⁴ and other non-auditory health conditions this association should be accounted for in future studies. Looking at the impact of comorbid health conditions on adverse vaccination effects is also required. Associations between other health conditions and audiovestibular symptom have been previously reported. Pyykkö et al. ²⁵ for instance identified that vestibular syncope (sudden and transient loss of consciousness) was associated with Tumarkin attacks, migraine and history of ischemic heart disease and history of cerebrovascular disease). It is also important to establish if there are any associations regarding previous COVID-19 infections and adverse vaccination effects. Further studies and systematic reviews are encouraged to identify the incidence and mechanisms of adverse audiovestibular vaccination effects.

Figshare: COVID 19 vaccine in Ménière's disease, https://doi.org/10.6084/m9.figshare.19519801. ²⁶

This project contains the following underlying data: -

COVID vaccine in MD for repository.xslx (raw data).

Figshare: COVID 19 vaccine in Ménière's disease, https://doi.org/10.6084/m9.figshare.19519801. ²⁶

This project contains the following extended data: -

Finnish_MD COVID Vaccination Questionnaire

Data are available under the terms of the Creative Commons Attribution 4.0 International license (CC-BY 4.0).