Study design and population
We performed a retrospective cohort study among PWH under routine
follow-up at the Infectious Diseases Unit of the IRCCS Ospedale Maggiore
Policlinico in Milan, Italy and enrolled in the Polimmune study, an
analysis conducted in our centre about immunogenicity of COVID-19
vaccines. Inclusion criteria were age >18 years,
immunization with mRNA-1273 vaccine according to the schedule of
attendance in the context of the Italian national vaccination program (a
primary schedule of 2 doses given 28 days apart followed by 1 booster
dose around 10 months after the first shot) and being stable on ART for
18 months before vaccination achieving viral suppression, defined as VL
<200 copies/mL. The main outcome was the occurrence of a VB,
defined as a VL between 20-200 copies/mL, in the 12 months since the
first vaccination shot. As a comparison, we evaluated the occurrence of
VB among the same individual in the 12 months before vaccination.
Demographic and clinical data were extracted from electronic medical
records. Participants had outpatient clinic visits every 4 months in
agreement with the Italian guidelines, performing VL quantification and
immunologic profiling at each time. Good adherence to ART was defined as
taking >90% of the doses according to the patient
self-report. Optimal immunologic response (OIR) was defined as CD4+
T/CD8+ T ratio ≥1 plus CD4+ T ≥500cells/µL plus CD4+ T ≥30%. Virologic
failure was defined as the detection of HIV RNA >200
copies/mL in at least two separate blood samples. As part of the
Polimmune study, enrolled individuals provided blood samples at T0
(enrolment), T1a (one month after the first dose), T1b (one month after
the second dose), T3 (three months after the first dose), T6 (six months
after the first dose), and T1c (one month after the first booster dose).
SARS-CoV-2 anti-N antibodies were assessed at T0, T3, T6 and T1c whereas
anti-S antibodies and antibody neutralisation activity (ND50) were
assessed at T1b.