Otitis media with effusion (OME), characterized by sterile fluid accumulation in the middle ear, is a well-documented sequela of upper respiratory tract infections (URTIs). Its pathogenesis is classically attributed to Eustachian tube dysfunction (ETD), often secondary to adenoid hypertrophy in children or mucosal inflammation or nasopharyngeal obstruction in adults (1, 2). Pediatric populations are more susceptible due to their anatomically shorter, more horizontal Eustachian tubes and frequent viral exposures (3). In adults, OME is relatively uncommon follows sporadic URTIs, with most cases resolving spontaneously. However, the emergence of SARS-CoV-2 has reshaped this paradigm, introducing novel etiopathogenic mechanisms and epidemiological trends.

The COVID-19 pandemic, initially marked by severe lower respiratory involvement (e.g., viral pneumonia), evolved with subsequent variants (e.g., Omicron) to predominantly cause upper respiratory symptoms—nasal congestion, pharyngitis, and ETD (4–6). This shift became particularly evident after China's December 2022 transition from its “Zero-COVID” policy, which led to widespread Omicron infections. Clinicians observed an unprecedented surge in post-COVID-19 OME cases, with adults reporting acute-onset aural fullness and conductive hearing loss, often persisting weeks after typical symptoms resolved (7–10). Recent investigations have demonstrated that SARS-CoV-2 was detected in 12% of MEE samples (median detection time: 21 days post-infection), providing compelling evidence for direct viral pathogenesis (11). Although comprehensive treatment regimens achieved an 83.6% success rate, the observed 8.2% recurrence rate highlights OME as a clinically significant post-COVID-19 complication (12). This emerging association between SARS-CoV-2 and OME presents both diagnostic challenges and opportunities for improved management strategies.

Accumulating evidence suggests SARS-CoV-2 may directly invade the middle ear mucosa. The virus's affinity for angiotensin-converting enzyme 2 (ACE2) receptors, abundantly expressed in the eustachian tube and middle ear epithelium, provides a plausible mechanism for viral entry and localized inflammation (5).

This study aims to systematically investigate the clinical and pathological characteristics of OME in patients with recent SARS-CoV-2 infection. Specifically, we will evaluate therapeutic outcomes and investigate if there is presence of SARS-CoV-2 in MEE, thereby enhancing our understanding of the link between post- SARS-CoV-2 infections and OME. We also focus on the type of hearing loss and the recovery rate respectively.

This retrospective observational study analyzed patients presenting with unilateral or bilateral ear fullness following SARS-CoV-2 infection at Jiangsu University Affiliated People's Hospital otolaryngology clinics between December 15, 2022 and January 20, 2023 (37-day period), with ethics approval (SQK-20240156-W). We examined SARS-CoV-2 diagnosis timing/method (antigen/nucleic acid test), OME onset timing, laterality (unilateral/bilateral), duration, accompanying tinnitus, and associated symptoms including fever, nasal congestion/rhinorrhea, cough (with/without sputum), and olfactory/gustatory dysfunction. Evaluations included pure-tone audiometry, tympanometry, endoscopy, optional CT scans, and prognostic outcomes.etc.

Our study demonstrates a clear temporal association between China's Omicron-dominant COVID-19 phase and a significant increase in OME incidence, with cases accounting for 9.5% of otolaryngology visits compared to baseline levels of 2.2%–2.5% This epidemiological shift, peaking 1-week post-infection with delayed clinical presentation (2–3 weeks), establishes OME as an important post-COVID-19 sequela. Notably, we identified prolonged viral persistence in middle ear effusions (32.7% PCR-positive) compared to concurrent nasopharyngeal samples (1.9%), suggesting the middle ear may serve as a viral reservoir even after upper respiratory tract clearance. The predominance of conductive hearing loss (71.2%) vs. mixed hearing loss (28.8%)—the latter carrying poorer prognosis particularly in elderly and comorbid patients—provides the first clinical stratification of post-COVID-19 auditory complications. These findings have immediate implications for otologic practice: The results highlight the need for: (1) routine middle ear monitoring in post-COVID-19 patients with ear symptoms, (2) prompt tympanocentesis for high-risk groups (elderly, diabetics, or those with mastoid abnormalities), and (3) customized follow-up based on hearing loss type. At a public health level, these data argue for including OME in post-COVID-19 syndrome monitoring frameworks and anticipatory resource allocation during future infection waves. The 9.6% treatment-refractory rate underscores the need for research into therapies targeting viral persistence mechanisms in the middle ear.

Previous studies have detected SARS-CoV-2 in various bodily fluids (13–15). Our finding of viral RNA in MEE samples suggests the eustachian tube may serve as a conduit for viral spread from the nasopharynx, consistent with Wu et al.'s report of higher nasopharyngeal viral loads (16). The virus may migrate retrogradely through the eustachian tube, which contains abundant ACE2-rich ciliated cells (17–19).

In one patient from our study, SARS-CoV-2 was detectable in the MEE 40 days post-infection, even though the nasopharyngeal swab had already tested negative. This suggests that the virus persists longer in the middle ear than in the upper respiratory tract, complicating treatment outcomes, particularly in patients history of similar episodes (20). However, despite the detection of SARS-CoV-2 in MEE, the Ct value of 37.30 indicates that its viability and pathogenicity had significantly decreased.

Clinically, patients typically developed fever and fatigue initially, followed by throat pain/cough within 1–2 days, and ear fullness approximately one week later—a progression consistent with eustachian tube anatomy. While the precise OME pathogenesis remains unclear, SARS-CoV-2's presence in the middle ear and ACE2 receptor distribution support potential direct infection or tubal dysfunction mechanisms (19, 21).

Of the 52 patients who underwent tympanocentesis, 59.6% required only one procedure, while 40.4% underwent multiple procedures. Additionally, 38.5% of the cases were bilateral. After three months of follow-up, 59.6% of patients were cured, 9.6% showed no improvement, and 30.8% were partially improved. Comorbidities, such as hypertension and poor mastoid pneumatization, were associated with poorer treatment outcomes, aligning with previous studies that have noted the influence of underlying health conditions on otologic complications (22, 23).

In terms of hearing outcomes, conductive hearing loss was the most common, although a few cases of mixed hearing loss were also observed. Our study showed that patients with mixed hearing loss generally had poorer prognoses compared to those with conductive hearing loss, highlighting the need for targeted audiological assessments. How does the COVID-19 impact on the inner ear? One hypothesis is that the affection of COVID-19 may lead to a hypercoagulable state of blood in the inner ear vessels, which is eventually caused cochlear ischemia, then hearing loss or even deafness may occur (24). Most cases of mixed hearing loss occurred in elderly patients (average age 67.8 ± 10.29), OME of whom may have had pre-existing mild sensorineural hearing loss. However, previous studies have speculated that SARS-CoV-2 infection could be a sole cause of sudden sensorineural hearing loss, raising the possibility that COVID-19 may contribute to nerve-related hearing loss, which presents as mixed hearing loss when combined with MEE (25, 26).

Interestingly, while viral infections are a common cause of OME, particularly in children due to the shorter and straighter structure of their eustachian tubes, we observed fewer cases in children during the pandemic, with a marked increase among adults (27). This could be attributed to the milder systemic symptoms of COVID-19 in children compared to adults.

This study has several limitations that warrant consideration. First, the retrospective design may introduce potential biases in data interpretation. Second, as a single-center study with a limited sample size, the generalizability of our findings requires further validation. Additionally, the 3-month follow-up period may be insufficient to evaluate long-term outcomes, and more comprehensive audiological assessments (e.g., repeat pure-tone audiometry and tympanometry) would strengthen the reliability of the results. Future multicenter prospective studies with extended follow-up durations and standardized audiological evaluations are needed to confirm our findings and further explore the long-term efficacy and safety of the intervention.

In summary, our study highlights the otologic manifestations of COVID-19 and suggests that middle and/or inner ear involvement may be an underrecognized complication. This finding reinforces the need for surveillance of post-COVID otologic complications, particularly in high-risk populations. Long-term follow-up studies should assess whether SARS-CoV-2-related OME increases the risk of chronic middle ear disease or hearing impairment. Further investigations should explore: (1) the precise mechanisms of viral entry into the middle ear, (2) the pathophysiological basis for sensorineural hearing loss (SNHL) development, and (3) evidence-based optimization of therapeutic strategies.