Varicella-Zoster Virus-Induced Neurologic Disease After COVID-19 Vaccination: A Multicenter Observational Cohort Study.

Background: Early reports described an increased risk of herpes zoster following receipt of mRNA-based COVID-19 vaccines. The objective was to assess whether COVID-19 vaccine is associated with varicella-zoster virus-induced neurologic disease (VZV-ND). Methods: This multicenter retrospective case-control study with a test-negative design was conducted at 12 hospitals in Israel. We included all patients admitted with VZV-ND between January 2020 and December 2021 and matched controls with a negative polymerase chain reaction result for VZV in cerebrospinal fluid. Results: We identified 188 patients meeting the case definition of VZV-ND who were admitted during the study period. Cases were matched with 376 controls. There was no significant variation in the incidence of VZV-ND between 1 year preceding and 1 year following the deployment of BNT162b2 in Israel. Analysis of persons who had received at least 1 dose of COVID-19 vaccine (n = 259) showed similar proportions of VZV-ND and non-VZV-ND in 4 intervals (30, 42, 50, 60 days) following the last vaccine dose. The median time from the last vaccine dose to hospitalization with a neurologic syndrome was 53 days (IQR, 25-128) and 82 days (IQR, 36-132) for VZV-ND and non-VZV-ND, respectively, not reaching statistical significance (P = .056). The rate of VZV-ND in vaccinated patients was no different from the rate in the unvaccinated group (30.9% vs 35.4%, P = .2). Conclusions: We did not find an association between COVID-19 vaccine and VZV-ND. Since COVID-19 vaccine is now recommended yearly, every fall and winter, establishing the safety of the vaccine is of great importance.

Secondary prophylaxis for Clostridioides difficile infection for patients on non-C. difficile antibiotics: a retrospective cohort study.

OBJECTIVES: Recurrent Clostridioides difficile infection (CDI) poses healthcare challenges and morbidity. Preventing recurrence with prophylactic oral CDI antibiotics lack consensus. METHODS: We used data from the largest healthcare provider in Israel to identify all adults aged 18 years or older diagnosed with a first episode of CDI (Index CDI) between February 2018 and December 2022 and subsequently received a non-CDI antibiotic within 2-8 weeks. Patients who received a concurrent prophylactic CDI antibiotic constituted the CDI prophylaxis group. Multivariable Cox proportional hazard regression models were used to examine the association of secondary CDI prophylaxis with CDI recurrence according to the severity of the index CDI (primary objective) and with 4- and 8-week all-cause mortality (secondary objective). RESULTS: A total of 434 eligible patients were included. Among them, 327 did not receive CDI antibiotic prophylaxis, while 107 did. CDI antibiotic prophylaxis was associated with a significant risk reduction of CDI recurrence with an adjusted HR of 0.51 (95% CI, 0.27-0.97). The magnitude of the association was modified by the severity of the index CDI episode (P for interaction 0.0182). Specifically, the HR for recurrence was 0.163 (95% CI 0.045-0.593) for non-severe CDI, and 1.242 (95% CI 0.524-2.946) for severe CDI. No significant association was found between CDI antibiotic prophylaxis and 4-8 weeks mortality. CONCLUSION: Secondary prophylaxis with CDI antibiotics appears to be associated with a reduced risk of recurrence in patients with previous non-severe CDI episode. Further studies are needed to confirm this finding.

Perceptions of organizational culture among infection preventionists in Israel, the United States, and Thailand: Results from national infection prevention surveys.

In national surveys of infection preventionists in Israel (n = 15), the United States (n = 415), and Thailand (n = 100), we found that views of organizational culture track well with these countries' cultural dimension scores of power distance and individualism. Our findings highlight the importance of considering cultural dimensions when implementing infection prevention efforts.

Association Between Guillain-Barré Syndrome and COVID-19 Infection and Vaccination: A Population-Based Nested Case-Control Study.

BACKGROUND AND OBJECTIVES: Existing data regarding occurrence of Guillain-Barré syndrome (GBS) after coronavirus disease 2019 (COVID-19) infection and vaccination are inconclusive. We aimed to assess the association between GBS and both severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and COVID-19 vaccine. METHODS: We conducted a nested case-control study in a cohort of 3,193,951 patients aged 16 years or older, without a diagnosis of prior GBS, from the largest health care provider in Israel. Participants were followed from January 1, 2021, until June 30, 2022, for the occurrence of GBS. Ten randomly selected controls were matched to each case of GBS on age and sex. We assessed both SARS-CoV-2 infection and COVID-19 vaccine administration in the prior 6 weeks in cases and controls. RESULTS: Overall, 76 patients were diagnosed with GBS during follow-up and were matched to 760 controls. A positive test for SARS-CoV-2 was detected in 9 (11.8%) cases and 18 (2.4%) controls. An administration of COVID-19 vaccine was detected in 8 (10.5%) cases (all Pfizer-BioNTech [BNT162b2] vaccine) and 136 (17.9%) controls (134 Pfizer-BioNTech vaccine). Multivariable conditional logistic regression models showed that the odds ratio for GBS associated with SARS-CoV-2 infection and COVID-19 vaccine administration was 6.30 (95% CI 2.55-15.56) and 0.41 (95% CI 0.17-0.96), respectively. The results were similar when exposure to SARS-CoV-2 infection or COVID-19 vaccine administration was ascertained in the prior 4 and 8 weeks, although did not reach statistical significance for COVID-19 vaccine at 4 weeks. DISCUSSION: Our study suggests that SARS-CoV-2 infection is associated with increased risk of GBS, whereas Pfizer-BioNTech COVID-19 vaccine is associated with decreased risk of GBS.

Association Between COVID-19 Infection and Pulmonary Fibrosis: A Nested Case-Control Study.

BACKGROUND: Pulmonary fibrosis is associated with significant morbidity. Data are scarce on the link between coronavirus disease (COVID-19) and pulmonary fibrosis. We aimed to assess the association between COVID-19 with pulmonary fibrosis. METHODS: We conducted a nested case-control study in a cohort of 2,894,801 adults without a diagnosis of pulmonary fibrosis. The underlying cohort consisted of members of the largest healthcare provider in Israel aged 18 years or older as of May 1, 2020. Subjects were followed up from cohort entry until June 30, 2022, for the occurrence of pulmonary fibrosis. Ten randomly selected controls were matched to each case of pulmonary fibrosis on age, sex, and calendar time. To account for surveillance bias a lag time of 60 days was used for ascertainment of prior COVID-19 and COVID-19 severity. RESULTS: During follow-up 1284 patients were newly diagnosed with pulmonary fibrosis and matched with 12,840 controls. Multivariable conditional logistic-regression models showed that the odds ratio for pulmonary fibrosis was 1.80 (95% confidence interval, 1.47-2.19) in patients with COVID-19 compared with no COVID-19. The multivariable odds ratio for pulmonary fibrosis was 1.33 (1.06-1.68), 2.98 (1.16-7.65), and 9.30 (5.77-14.98) for mild, moderate, and severe COVID-19, respectively, compared with no COVID-19. The magnitude of the association was attenuated but remained statistically significant for severe disease when the lag time was extended to 180 days (1.08 [0.78-1.49], 2.37 [0.75-7.46], and 5.34 [2.75-10.36] for mild, moderate, and severe COVID-19, respectively). CONCLUSIONS: COVID-19 appears to be associated with an increased risk of pulmonary fibrosis and the magnitude of the association increases with COVID-19 severity.

Association between SARS-CoV-2 infection and new-onset atrial fibrillation.

BACKGROUND: Atrial fibrillation (AF) is associated with substantial morbidity and mortality. New-onset AF (NOAF) has been related recently to SARS-CoV-2 infection; however, the evidence supporting this link is still scarce. We aimed to examine the association between SARS-CoV-2 infection and NOAF. METHODS: We conducted a nested-case control study in a cohort of 2,931,046 adults from the largest healthcare provider in Israel. Subjects were followed from March 1st, 2020, until June 30th, 2022, for the occurrence of NOAF. Ten randomly selected controls were matched to each case of NOAF on age, sex, and duration of follow-up. Exposure to SARS-CoV-2 infection in the prior 30 days was assessed in cases and controls. To account for surveillance bias we performed a lag-time analysis and assessed the association with a negative control exposure (low back pain). Data was analyzed using conditional logistic regression. RESULTS: During the follow-up 18,981 patients developed NOAF and were matched to 189,810 controls. The mean age of cases and matched controls was 73.8 ± 13 years, and 51.1% of them were women. Multivariable analysis showed that SARS-CoV-2 infection was associated with an increased risk of NOAF; adjusted-OR, 4.24 (95% CI, 3.89-4.62). The association remained significant on lag-time analysis; however, the strength of the association was gradually attenuated with increasing lag-time but stabilized around a lag-time of 20 days. The negative control exposure (low back pain) was associated only with small increased risk of NOAF; adjusted-OR of 1.13 (95% CI, 1.02-1.26). CONCLUSION: SARS-CoV-2 infection appears to be associated with increased risk of NOAF.

Association between COVID-19 vaccination and myasthenia gravis: A population-based, nested case-control study.

BACKGROUND: Existing data regarding the link between COVID-19 vaccine and myasthenia gravis (MG) are scarce. We aimed to assess the association between Pfizer-BioNTech vaccine with both new-onset MG and MG exacerbation. METHODS: For the first aim, we conducted a nested case-control study in a cohort of 3,052,467 adults, without a diagnosis of MG, from the largest healthcare provider in Israel. Subjects were followed from January 1, 2021 until June 30, 2022 for the occurrence of MG. Ten randomly selected controls were matched to each case of new-onset MG on age and sex. For the second aim, a nested case-control study was conducted in a cohort of 1446 MG patients. Four randomly selected MG patients (controls) were matched to each case of MG exacerbation. Exposure to COVID-19 vaccine in the prior 4 weeks was assessed in cases and controls. RESULTS: Overall, 332 patients had new-onset MG and were matched with 3320 controls. Multivariable conditional logistic regression models showed that the odds ratio (OR) for new-onset MG, associated with COVID-19 vaccine, was 1.14 (95% CI 0.73-1.78). The results were consistent in sensitivity analysis that used more stringent criteria to define MG. Overall, 62 patients with MG exacerbation were matched to 248 MG controls. The multivariable OR for MG exacerbation, associated with COVID-19 vaccine, was 1.35 (95% CI 0.37-4.89). All results were similar when the prior exposure to COVID-19 vaccine was extended to 8 weeks. CONCLUSION: This study suggests that Pfizer-BioNTech vaccine is not associated with increased risk of new-onset nor exacerbation of MG.

Correlates of protection for booster doses of the SARS-CoV-2 vaccine BNT162b2.

Vaccination, especially with multiple doses, provides substantial population-level protection against COVID-19, but emerging variants of concern (VOC) and waning immunity represent significant risks at the individual level. Here we identify correlates of protection (COP) in a multicenter prospective study following 607 healthy individuals who received three doses of the Pfizer-BNT162b2 vaccine approximately six months prior to enrollment. We compared 242 individuals who received a fourth dose to 365 who did not. Within 90 days of enrollment, 239 individuals contracted COVID-19, 45% of the 3-dose group and 30% of the four-dose group. The fourth dose elicited a significant rise in antibody binding and neutralizing titers against multiple VOCs reducing the risk of symptomatic infection by 37% [95%CI, 15%-54%]. However, a group of individuals, characterized by low baseline titers of binding antibodies, remained susceptible to infection despite significantly increased neutralizing antibody titers upon boosting. A combination of reduced IgG levels to RBD mutants and reduced VOC-recognizing IgA antibodies represented the strongest COP in both the 3-dose group (HR = 6.34, p = 0.008) and four-dose group (HR = 8.14, p = 0.018). We validated our findings in an independent second cohort. In summary combination IgA and IgG baseline binding antibody levels may identify individuals most at risk from future infections.

Unveiling the hidden threat of carbapenemase-producing Enterobacteriaceae in hospital water environments: A single-center study.

This retrospective study examined the presence of carbapenemase-producing Enterobacteriaceae in hospital water environments. Results showed that carbapenemase-producing Enterobacteriaceae was detected in 41.5% of the samples within 1 m of a water source (showers or sinks), with 20.6% of the positive samples associated with shower water sources.

Analysis of four carbapenem-resistant Acinetobacter baumannii outbreaks using Fourier-transform infrared spectroscopy.

We used Fourier-transform infrared (FTIR) spectroscopy to analyze 4 carbapenem-resistant Acinetobacter baumannii outbreaks. FTIR distinguished between isolates from different hospitals and uncovered the relatedness between isolates from acute-care hospitals and a post-acute-care hospital. Using higher cutoffs reveals more distant relationships and lower cutoffs support analyses of recent events.

Effectiveness of Paxlovid in Reducing Severe Coronavirus Disease 2019 and Mortality in High-Risk Patients.

BACKGROUND: Paxlovid was granted an Emergency Use Authorization for the treatment of mild to moderate coronavirus disease 2019 (COVID-19), based on the interim analysis of the Evaluation of Protease Inhibition for COVID-19 in High-Risk Patients (EPIC-HR) trial. Paxlovid effectiveness needs to be assessed in a noncontrolled setting. In this study we used population-based real-world data to evaluate the effectiveness of Paxlovid. METHODS: The database of the largest healthcare provider in Israel was used to identify all adults aged 18 years or older with first-ever positive test for severe acute respiratory syndrome coronavirus 2 between January and February 2022, who were at high risk for severe COVID-19 and had no contraindications for Paxlovid use. Patients were included irrespective of their COVID-19 vaccination status. Cox hazard regression was used to estimate the 28-day hazard ratio (HR) for severe COVID-19 or mortality with Paxlovid examined as time-dependent variable. RESULTS: Overall, 180 351 eligible patients were included; of these, only 4737 (2.6%) were treated with Paxlovid, and 135 482 (75.1%) had adequate COVID-19 vaccination status. Both Paxlovid and adequate COVID-19 vaccination status were associated with significant decrease in the rate of severe COVID-19 or mortality with adjusted HRs of 0.54 (95% confidence interval [CI], .39-.75) and 0.20 (95% CI, .17-.22), respectively. Paxlovid appears to be more effective in older patients, immunosuppressed patients, and patients with underlying neurological or cardiovascular disease (interaction P < .05 for all). No significant interaction was detected between Paxlovid treatment and COVID-19 vaccination status. CONCLUSIONS: This study suggests that in the era of Omicron and in real-life settings, Paxlovid is highly effective in reducing the risk of severe COVID-19 or mortality.

Effectiveness of Evusheld in Immunocompromised Patients: Propensity Score-Matched Analysis.

BACKGROUND: Tixagevimab and cilgavimab, a combined monoclonal antibody (Evusheld), was granted emergency use authorization for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) preexposure prophylaxis in individuals with immunocompromising conditions. In this study we used population-based real-world data to evaluate the effectiveness of Evusheld in immunocompromised patients. METHODS: Using the computerized database of the largest healthcare provider in Israel, we identified all adult immunocompromised patients who were eligible to receive Evusheld (150 mg tixagevimab and 150 mg cilgavimab) on 15 February 2022. Patients with a documentation of a prior SARS-CoV-2 infection were excluded. A total of 703 patients who received Evusheld were propensity score matched, using a ratio of 1:4, with 2812 patients who had not received Evusheld (control group). Patients were followed through 30 June 2022 for up to 90 days for the first documentation of SARS-CoV-2 infection and coronavirus disease 2019 (COVID-19)-related hospitalization. RESULTS: Overall, 72 patients in the Evusheld group and 377 patients in the control group had SARS-CoV-2 infection, reflecting an incidence rate of 4.18 and 5.64 per 100 person-months, respectively. The hazard ratios were 0.75 (95% confidence interval [CI]: .58-.96) for SARS-CoV-2 infection and 0.41 (95% CI: .19-.89) for COVID-19-related hospitalization in the Evusheld group compared to the control group. The magnitude of relative risk reduction of each outcome was greater in nonobese patients (P for interaction = .020 and .045, respectively). CONCLUSIONS: This study suggests that Evusheld is effective in reducing the risk of SARS-CoV-2 infection and COVID-19 hospitalization in immunocompromised patients. The effectiveness of this dose appears to be greater in nonobese patients.

Effectiveness of Molnupiravir in High-Risk Patients: A Propensity Score Matched Analysis.

BACKGROUND: Molnupiravir was granted emergency use authorization for the treatment of mild to moderate coronavirus disease 2019 (COVID-19). In this study, we used population-based real-world data to evaluate the effectiveness of molnupiravir. METHODS: The database of the largest healthcare provider in Israel was used to identify all adults with first-ever positive test for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) performed in the community during January-February 2022, who were at high risk for severe COVID-19, and had no contraindications for molnupiravir use. Patients were included regardless of SARS-CoV-2 vaccination status. A total of 2661 patients who received molnupiravir were propensity score matched with 2661 patients who have not received molnupiravir (control group). Patients were followed through 10 March 2022 for up to 28 days for the first occurrence of the composite severe COVID-19 or COVID-19-specific mortality. RESULTS: The composite outcome occurred in 50 patients in the molnupiravir group and 60 patients in the control group. Molnupiravir was associated with a nonsignificant reduced risk of the composite outcome: hazard ratio, 0.83 (95% confidence interval, .57-1.21). However, subgroup analyses showed that molnupiravir was associated with a significant decrease in the risk of the composite outcome in older patients 0.54 (0.34-0.86), in females 0.41 (0.22-0.77), and in patients with inadequate COVID-19 vaccination 0.45 (0.25-0.82). The results were similar when each component of the composite outcome was examined separately. CONCLUSIONS: This study suggests that in the era of Omicron and in real-life setting, molnupiravir might be effective in reducing the risk of severe COVID-19 and COVID-19-related mortality, particularly in specific subgroups.

Healthcare-associated infection prevention and control practices in Israel: results of a national survey.

BACKGROUND: Healthcare-associated infection (HAI) is a common and largely preventable cause of morbidity and mortality. The COVID-19 pandemic has presented unprecedented challenges to health systems. We conducted a national survey to ascertain hospital characteristics and the use of HAI prevention measures in Israel. METHODS: We e-mailed surveys to infection prevention and control (IPC) leads of acute care hospitals in Israel. The survey included questions about the use of practices to prevent catheter-associated urinary tract infection (CAUTI), central line-associated bloodstream infection (CLABSI), ventilator-associated pneumonia (VAP), and Clostridioides difficile infection (CDI). The survey also assessed COVID-19 impact and healthcare worker well-being. RESULTS: IPC leads from 15 of 24 invited hospitals (63%) completed the survey. Only one-third of respondents reported strong support for IPC from hospital leadership. Although several prevention practices were used by all hospitals (e.g., maximum sterile barrier precautions for CLABSI and real-time assessment of environmental cleaning for CDI), use of other practices was suboptimal-particularly for CAUTI and VAP. COVID-19 had a profound impact on Israeli hospitals, with all hospitals reporting opening of new units to care for COVID patients and most reporting moderate to extreme financial hardship. All hospitals reported highly successful plans to vaccinate all staff and felt confident that the vaccine is safe and effective. CONCLUSION: We provide a status report of the IPC characteristics and practices Israeli hospitals are currently using to prevent HAIs during the COVID-19 era. While many globally accepted IPC practices are widely implemented, opportunities to increase the use of certain IPC practices in Israeli hospitals exist.

Immunity waning after COVID vaccine booster vs. infection-better than expected.

BACKGROUND: Rapid decline in antibody-titres after BNT162b2 mRNA COVID-19 vaccine was reported; thus, a booster dose, and recently a second booster were approved. The study aims to discuss immunogenicity throughout the pandemic, especially after booster dose. METHODS: A prospective study conducted in EMMS-Nazareth hospital, Israel. Anti-SARS-CoV-2 IgG antibody titres were monitored every 5 weeks starting from the vaccine's second dose. To detect symptomatic and asymptomatic infections, nasopharyngeal swabs for COVID-19 PCR were obtained bi-weekly, and on suggestive symptoms. Third dose of the vaccine was suggested for all participants 5 months after the second one. A comparison was made between those who received three doses (booster-group), and those who were infected after having two doses (infection-group) or three doses (booster-infection) group. RESULTS: One-hundred participants were included; 66 finished 14 months of follow-up, out of whom 40 received a third dose, 10 received only two doses-all were infected (mean time for infection 5 ± 12.15 weeks before the designated booster), and 12 received three doses and were infected. The mean titres of these three groups 7 months after the designated booster dose (regardless of receiving it) were 1756 ± 2279; 3483 ± 3016 and 6925 ± 3720 BAU/mL, respectively. The booster group had high titres 7 months after the booster dose, comparable to two months after the second dose (p = .69); The booster-infected group had even higher titres. CONCLUSION: Immunogenicity decline rate after the booster dose is slower than the second dose. Timing of second booster in general population is still to be determined; neutralizing-antibody titres might be helpful.

Hospitalised patients with breakthrough COVID-19 following vaccination during two distinct waves in Israel, January to August 2021: a multicentre comparative cohort study.

BackgroundChanging patterns of vaccine breakthrough can clarify vaccine effectiveness.AimTo compare breakthrough infections during a SARS-CoV-2 Delta wave vs unvaccinated inpatients, and an earlier Alpha wave.MethodsIn an observational multicentre cohort study in Israel, hospitalised COVID-19 patients were divided into three cohorts: breakthrough infections in Comirnaty-vaccinated patients (VD; Jun-Aug 2021) and unvaccinated cases during the Delta wave (ND) and breakthrough infections during an earlier Alpha wave (VA; Jan-Apr 2021). Primary outcome was death or ventilation.ResultsWe included 343 VD, 162 ND and 172 VA patients. VD were more likely older (OR: 1.06; 95% CI: 1.05-1.08), men (OR: 1.6; 95% CI: 1.0-2.5) and immunosuppressed (OR: 2.5; 95% CI: 1.1-5.5) vs ND. Median time between second vaccine dose and admission was 179 days (IQR: 166-187) in VD vs 41 days (IQR: 28-57.5) in VA. VD patients were less likely to be men (OR: 0.6; 95% CI: 0.4-0.9), immunosuppressed (OR: 0.3; 95% CI: 0.2-0.5) or have congestive heart failure (OR: 0.6; 95% CI: 0.3-0.9) vs VA. The outcome was similar between all cohorts and affected by age and immunosuppression and not by vaccination, variant or time from vaccination.ConclusionsVaccination was protective during the Delta variant wave, as suggested by older age and greater immunosuppression in vaccinated breakthrough vs unvaccinated inpatients. Nevertheless, compared with an earlier post-vaccination period, breakthrough infections 6 months post-vaccination occurred in healthier patients. Thus, waning immunity increased vulnerability during the Delta wave, which suggests boosters as a countermeasure.

Association Between the BNT162b2 Messenger RNA COVID-19 Vaccine and the Risk of Sudden Sensorineural Hearing Loss.

IMPORTANCE: Identification of adverse events after vaccination increases awareness of vaccine-associated complications, leading to early diagnosis and treatment. Evidence remains scarce on the association between the BNT162b2 messenger RNA (mRNA) COVID-19 vaccine (Pfizer-BioNTech) and sudden sensorineural hearing loss (SSNHL). OBJECTIVE: To assess the association between the BNT162b2 mRNA COVID-19 vaccine and SSNHL. DESIGN, SETTING, AND PARTICIPANTS: This retrospective, population-based cohort study was performed from December 20, 2020, to May 31, 2021, using data from the largest health care organization in Israel. Patients 16 years or older who received the first vaccine dose between December 20, 2020, and April 30, 2021, and the second vaccine dose between January 10, 2021, and April 30, 2021, were included. EXPOSURES: Receipt of first and second BNT162b2 mRNA COVID-19 vaccine doses. MAIN OUTCOMES AND MEASURES: The main outcome was SSNHL based on International Classification of Diseases, Ninth Revision (ICD-9) codes in conjunction with concurrent prednisone dispensing. Observed cases of SSNHL, occurring within 21 days after each of the first and second vaccine doses, were compared with the expected cases based on the experience of the population in 2018 and 2019. Standardized incidence ratios (SIRs) and attributable risks were computed. RESULTS: Overall, 2 602 557 patients (mean [SD] age, 46.8 [19.6] years; 51.5% female) received the first dose of BNT162b2 mRNA COVID-19 vaccine, with 91 cases of SSNHL reported. Of these patients, 2 441 719 (93.8%) received the second vaccine dose, with 79 cases of SSNHL reported. The age- and sex-weighted SIRs were 1.35 (95% CI, 1.09-1.65) after the first vaccine dose and 1.23 (95% CI, 0.98-1.53) after the second vaccine dose. After the first vaccine dose, the estimated SIRs were more pronounced in female patients aged 16 to 44 years (SIR, 1.92; 95% CI, 0.98-3.43) and female patients 65 years or older (SIR, 1.68; 95% CI, 1.15-2.37). After the second vaccine dose, the highest estimated SIR was observed in male patients 16 to 44 years (SIR, 2.45; 95% CI, 1.36-4.07). The attributable risks were generally small, and the results were similar when 2019 was used as a reference to estimate the expected number of SSNHL cases. CONCLUSIONS AND RELEVANCE: This study suggests that the BNT162b2 mRNA COVID-19 vaccine might be associated with increased risk of SSNHL; however, the effect size is very small. Further studies are warranted to establish this possible association.