Incidence of Confirmed Influenza and Pneumococcal Infections and Vaccine Uptake Among Virologically Suppressed People Living with HIV

Background/Objectives: Influenza and Streptococcus pneumoniae infections are common vaccine-preventable diseases to which people living with HIV (PLWH) may be more susceptible. This study aims to investigate the incidence of confirmed influenza and pneumococcal infections, and to determine the incidence rate (IR) and factors associated with vaccine uptake in a population of virologically suppressed PLWH. Methods: We included 1031 virologically suppressed PLWH from the Copenhagen Comorbidity in HIV Infection (COCOMO) study. Data on infections and vaccinations between 2015 and 2020 were collected from nationwide registries. Incidence rates with 95% confidence intervals (CIs) of confirmed influenza and pneumococcal infections and vaccine uptake were calculated, and predictors of vaccine uptake were explored using logistic regression. Results: The IR of influenza showed variation from year to year and ranged between 0 (95% CI: 0.0, 7.6) and 18.0 (95% CI: 8.2, 34.1) per 1000 person-years at risk with an overall IR of 8.4 per 1000 person-years at risk (95% CI: 5.4, 12.3). The overall IR of pneumococcal infections was 5.5 per 1000 person-years at risk (95% CI: 3.9, 7.5). Among PLWH, 53.2% were influenza-vaccinated at least once, 72.3% and 22.6% of PLWH were vaccinated at least twice and in all six seasons, respectively, while 31% had at least one pneumococcal vaccine. Previous pneumonia or bronchitis, higher body mass index, use of drugs to treat heart conditions, and longer time with HIV were independently associated with vaccine uptake. Conclusions: We found high incidences of confirmed influenza and pneumococcal infections in virologically suppressed PLWH, but vaccine uptake was below recommendations, highlighting the need for improved vaccination counseling.