Vaccination coverage of persons using hospital outpatient mental health services at Heraklion, Crete, Greece: A cross-sectional study during pandemic

Persons with mental health disorders are vulnerable, with demanding care needs. This cross-sectional study aimed to report on their vaccination coverage against COVID-19 and common vaccine-preventable diseases. The study was conducted from September to November 2022 at the psychiatric outpatient settings of Venizeleion General Hospital of Heraklion, Crete, Greece, and the Mental Health Center of Heraklion. Information was collected via personal medical interview and prescription data. The study population included 361 participants, with a mean age of 49.8±14.3 years, 59.0% women. The most common diagnoses were recurrent depressive disorder (24.1%), schizophrenia (22.7%), anxiety disorder (21.3%), and bipolar disorder (15.7%). Vaccination coverage against seasonal influenza for 2020, 2021, and 2022 was 43.2%, 39.8%, and 40.7%, respectively. Pneumococcal vaccination included the conjugate (28.8%) and polysaccharide (7.7%) vaccines. Vaccination against Tetanus, Diphtheria, Pertussis (TDP) accounted for 11.0%, Hepatitis B for 5.8%, and Herpes Zoster for 27.1%. COVID-19 vaccination, with at least one booster dose, reached a high 73.6%. Patients with severe mental illness, 139 out of 361, were less likely to have contracted COVID-19 (50/139, 35.9%) than those without (108/222, 46.6%), (p=0.018). Coverage with polysaccharide vaccine, TDP, and Hepatitis B, was very low. Patients annually vaccinated for influenza in the last three consecutive years were most likely to be fully vaccinated for pneumococcal disease and for COVID-19 (with at least one booster dose). Future research and clinical practice should focus on identifying patients at risk of not receiving preventive services, such as vaccines.