Importance: Spontaneous adverse reaction reports of sudden hearing loss have been observed, and a population-based cohort study conducted in Israel showed an increase in the incidence of sudden sensorineural hearing loss (SSNHL) following vaccination with messenger RNA COVID-19 vaccine BNT162b2 (Pfizer-BioNTech). However, in this setting, the possibility of confounding remained.Objective: To assess a potential association between COVID-19 vaccinations and SSNHL.Design, Setting, and Participants: This register-based country-wide retrospective cohort study of 5.5 million Finnish residents was conducted from January 1, 2019, to April 20, 2022, and included all individuals who were identified from the population information system who were alive or born during the study period except individuals who had SSNHL during 2015 to 2018 according to specialized care derived diagnosis codes for SSNHL (International Statistical Classification of Diseases and Related Health Problems, Tenth Revision [ICD-10] code H91.2) as a primary or secondary diagnosis.Exposures: The a priori primary risk period was 0 to 54 days following each COVID-19 vaccination. The risk periods for different vaccine doses did not overlap so that a later vaccine exposure ended the previous risk period. The secondary risk period was from 55 days following each COVID-19 vaccination until a subsequent COVID-19 vaccination. A secondary analysis included a risk time from 0 to 54 days following a positive polymerase chain reaction test result for SARS-CoV-2.Main Outcomes and Measures: The incidences of SSNHL following COVID-19 vaccination were compared with the incidences before the COVID-19 epidemic in Finland. The Poisson regression model included calendar time, age, sex, diabetes, cardiovascular disease, other chronic diseases, and the number of visits in primary health care.Results: For the 5.5 million Finnish residents included in the study, the comparison time comprised 6.5 million person-years, the primary risk time of 1.7 million person-years, and the secondary risk time of 2.1 million person-years. Before the COVID-19 epidemic in Finland, 18.7/100 000 people received a diagnosis of SSNHL annually. The study data suggested no increased risk for SSNHL following any COVID-19 vaccination. In particular, adjusted incidence rate ratios with 95% confidence intervals for the BNT162b2 vaccine’s 3 doses were 0.8 (95% CI, 0.6-1.0), 0.9 (95% CI, 0.6-1.2), and 1.0 (95% CI, 0.7-1.4), respectively. There was no association between SARS-CoV-2 infection and an increased incidence of SSNHL.Conclusions and Relevance: The results of this cohort study show no evidence of an increased risk of SSNHL following COVID-19 vaccination. The study accounted for previous disease and other potential confounding factors. These results are based on diagnosis codes in specialized care but still need to be verified in settings that are capable of evaluating the degree of hearing loss.

Safe vaccination is essential for mitigation of the COVID-19 pandemic. Two adenoviral vector vaccines, ChAdOx1 nCov-19 (AstraZeneca) and Ad26.COV2.S (Johnson&Johnson/Janssen) have shown to be effective and they are distributed globally, but reports on serious cerebral venous sinus thrombosis (CVST) associated with thrombocytopenia, have emerged. Our objective was to evaluate the background incidence of CVST with thrombocytopenia and to compare it to incidences following COVID-19 vaccines. We conducted a register-based nation-wide cohort study in Finland, including all 5.5 million individuals alive in Finland, 1 Jan 2020. COVID-19 vaccinations registered in the National Vaccination Register served as the exposure. We detected CVST admissions or hospital visits recorded in the hospital discharge register from Jan 1, 2020 through April 2, 2021. We confirmed the diagnosis of CVST and thrombocytopenia (platelet count <150,000 per cubic millimeter) using radiology reports and laboratory data. By Poisson regression, we compared the baseline incidences to the risks within four weeks after COVID-19 vaccinations. Out of the 167 CVST episodes identified in the registers, 117 were confirmed as CVST, 18 of which coincided with thrombocytopenia (baseline incidence 0.18 per 28 days per million persons). We found 2 episodes of CVST with thrombocytopenia within 28 days of the first ChAdOx1 nCov-19 vaccination (among 200,397 vaccinated, aged 16 or above). No cases were found following the first mRNA vaccine dose among 782,604 vaccinated. The background incidence of CVST combined with thrombocytopenia was minuscule compared to the incidence during the weeks following the ChAdOx1 nCov-19 vaccination. Accurate estimation of the baseline incidence is essential in the critical appraisal of the benefit-risk of any vaccination program.

Epidemiological studies and animal models suggest that early postnatal nutrition and growth can influence adult health. However, few human studies have objective recordings of early nutrient intake. We studied whether nutrient intake and growth during the first 9 weeks after preterm birth with very low birth weight (VLBW, <1500 g) predict total energy intake, resting energy expenditure (REE), physical activity and food preferences in young adulthood. We collected daily nutritional intakes and weights during the initial hospital stay from hospital records for 127 unimpaired VLBW participants. At an average age 22.5 years, they completed a three-day food record and a physical activity questionnaire and underwent measurements of body composition (dual X-ray absorptiometry; n = 115 with adequate data) and REE (n = 92 with adequate data). We used linear regression and path analysis to investigate associations between neonatal nutrient intake and adult outcomes. Higher energy, protein and fat intakes during the first three weeks of life predicted lower relative (=per unit lean body mass) energy intake and relative REE in adulthood, independent of other pre- and neonatal factors. In path analysis, total effects of early nutrition and growth on relative energy intake were mostly explained by direct effects of early life nutrition. A path mediated by early growth reached statistical significance only for protein intake. There were no associations of neonatal intakes with physical activity or food preferences in adulthood. As a conclusion, higher intake of energy and nutrients during first three weeks of life of VLBW infants predicts energy balance after 20 years. This association is partly mediated through postnatal growth.

People born preterm have reduced BMD, subnormal peak bone mass, and an increased risk of osteoporosis. Whether this translates to increased risk of bone fractures is uncertain. We assessed fracture risk from childhood to early adulthood in relation to gestational age and sex by conducting a nationwide register-linkage cohort study comprising all 223 615 liveborn (January 1987–September 1990) singletons (9161, 4.1%; preterm) in Finland. Cox regression models provided hazard ratios (HRs) for fracture diagnosis in public specialty health care in both first and recurrent event settings during the whole follow-up (0–29 years) and during different age periods (0–4, 5–9, 10–29 years). Gestational age was considered categorical (full-term, 39–41 weeks; reference). A total of 39 223 (17.5%) children or young adults had at least 1 fracture. In analyses not stratified by sex, only extremely preterm birth (<28 completed weeks’ gestation) was associated with risk of bone fracture at 0–29 years (adjusted HR [aHR]: 0.46; 95% CI: 0.28–0.74) compared with those born full-term. Among females, gestational age was unrelated to fracture risk at 0–29 years. Among males, extremely and very preterm (28–31 weeks) birth was associated with lower risk of fracture at 0–29 years compared with those born full-term (aHR: 0.38 [95% CI: 0.21–0.71] and 0.75 [95% CI: 0.59–0.95], respectively). Restricting the analyses to the individuals without severe medical condition(s) attenuated the associations. However, the fracture risk varied according age and sex: at 10–29 years, moderately preterm (32–33 weeks) females and extremely and very preterm males had a lower risk (aHR: 0.63 [0.43–0.94], 0.35 [0.17–0.69], and 0.74 [0.57–0.95], respectively), while late-preterm birth (34–36 weeks) was associated with a 1.6-fold higher risk among females at 0–5 years, and a 1.4-fold risk among males at 5–10 years. Analyses on recurrent fractures showed a similar pattern. Children and young adults, in particular males, born extremely or very preterm may have fewer bone fractures; this is partly explained by severe medical conditions in this group.

Importance: Spontaneous adverse reaction reports of sudden hearing loss have been observed and a population-based cohort study conducted in Israel showed an increase in the incidence of sudden sensorineural hearing loss (SSNHL) following vaccination with messenger RNA COVID-19 vaccine BNT162b2 (Pfizer-BioNTech). However, in this setting, possibility of confounding remained. Objective: To assess a potential association between COVID-19 vaccinations and SSNHL. Design: A register-based country-wide observational study with study period from January 1, 2019, until Apr 12, 2022. Setting: Residents in Finland: 5,8 million. Participants: All individuals identified from population information system alive or born during the study period except individuals having SSNHL during 2015 to 2018 according to specialized care derived diagnosis codes for SSNHL (ICD10-code H91.2) as a primary or secondary diagnosis. Exposures: The a priori primary risk period was 0 to 54 days following each COVID-19 vaccine dose. The secondary risk time was 55 or more days after the vaccination. A later vaccine exposure overruled a previous one. A secondary analysis included a risk time of 0 to 54 days following a positive polymerase chain reaction (PCR) test for SARS-CoV-2. Main Outcome: We compared incidences of SSNHL following COVID-19 vaccination to incidences before the COVID-19 epidemic in Finland. In our Poisson regression analysis, we adjusted for calendar time, age, sex, diabetes, cardiovascular disease, other chronic diseases, number of visits in primary health care. Results: Comparison time constituted of 6.5 million person years, primary risk time of 1.7 million person years, and secondary risk time of 2.1 million person years. Before the epidemic yearly 18.7 / 100,000 people were diagnosed with SSNHL. Our data suggested no increased risk for SSNHL following any COVID-19 vaccination. In particular, adjusted incidence rate ratios, with 95 percent confidence intervals (95% CI) for the BNT162b2 vaccine’s three doses were 0.8 (95% CI 0.6 to 1.0), 0.9 (95% CI 0.6 to 1.2), and 1.3 (95% CI 0.9 to 2.0). SARS-CoV-2 infection was not associated with an increased incidence of SSNHL either. Conclusions and relevance: Our results show no evidence of increased SSNHL with the COVID-19 vaccinations. We accounted for previous disease and other potential confounding factors. Our results base on diagnosis codes in specialized care but still need to be verified with settings, that are capable to evaluate the degree of hearing loss. Key Points: Question: Are COVID-19 vaccinations associated with sudden sensorineural hearing loss (SSNHL), when assessed in a register-based country-wide observational study with data on potential confounding factors? Findings: Our data suggested no increased risk for SSNHL following any COVID-19 vaccination. Meaning: A large previous cohort study shows an increased risk for SSNHL following vaccine BNT162b2 (Pfizer-BioNTech) – our results, that take pre-existing disease into account, demonstrate no such an effect.