Table 1.

SPIRIT figure

Timepoint	Enrolment	Allocation and vaccine administration	Post-allocation	Close-out
	Prior to or on Day 0	Day 0	3 months after vaccination	May 31, 2022
Enrolment
Eligibility screen	X
Informed consent	X
Allocation		X
Interventions
QIV-HD		X
QIV-SD		X
Assessments
Registry-based safety assessment			X
Registry-based endpoint assessment				X

QIV-HD high-dose quadrivalent influenza vaccine, QIV-SD standard-dose quadrivalent influenza vaccine