Background: Due to an increased risk of sexually transmitted infections (STIs), gay, bisexual and other men who have sex with men (MSM) have been recommended to receive vaccinations against human papillomavirus, meningitis C and hepatitis A/B. This review aimed to compare the rates of vaccine acceptability, uptake and completion, and to identify determinants of vaccine outcomes specific to MSM to inform a theoretical framework.Methods: In January 2020 four databases were explored to identify vaccination behaviours and associated factors among MSM. A narrative systematic review and meta-analysis were performed. Data were synthesised for theoretical modelling. Results: Seventy-eight studies, mostly from the USA, were included. The average vaccine acceptability was 63% (median=72%, range: 30%-97%), vaccine uptake 45% (median=42%, range: 5%-100%) and vaccine completion 47% (median=45%, range: 12%-89%). Six categories of factors associated with vaccination acceptability, uptake and completion were conceptualised:Individual (e.g., demographic and psychosocial); Interpersonal (e.g., peer education); Healthcare provider (e.g., vaccine recommendation); Organisational and practice setting (e.g., routine collection of patient sexual orientation information that is integrated into a clinical decision support system); Community environment (e.g., targeted health promotion campaigns); and National, state and local policy environment (e.g., public health guidelines targeting MSM). Conclusion: Despite overall high levels of acceptability, uptake and completion rates were below targets predicted by cost-effectiveness modelling across all recommended vaccines. These parameters may need to be adjusted for more precise estimations of cost-effectiveness. Addressing the multiple levels of determinants, as outlined in our theoretical framework, will help guide interventions to increase vaccine completion among MSM.

Drainage of interstitial fluid from the brain occurs via the intramural periarterial drainage (IPAD) pathways along the basement membranes of cerebral capillaries and arteries against the direction of blood flow into the brain. The cerebrovascular smooth muscle cells (SMCs) provide the motive force for driving IPAD, and their decrease in function may explain the deposition of amyloid-beta as cerebral amyloid angiopathy (CAA), a key feature of Alzheimer’s disease. The α-adrenoceptor subtype α1A is abundant in the brain, but its distribution in the cerebral vessels is unclear. We analysed cultured human cerebrovascular SMCs and young, old and CAA human brains for (a) the presence of α1A receptor and (b) the distribution of the α1A receptor within the cerebral vessels. The α1A receptor was present on the wall of cerebrovascular SMCs. No significant changes were observed in the vascular expression of the α1A-adrenergic receptor in young, old and CAA cases. The pattern of vascular staining appeared less punctate and more diffuse with ageing and CAA. Our results show that the α1A-adrenergic receptor is preserved in cerebral vessels with ageing and in CAA and is expressed on cerebrovascular smooth muscle cells, suggesting that vascular adrenergic receptors may hold potential for therapeutic targeting of IPAD.