MEDLINE (supplier OVID) will be searched with a standard filter for RCT (Dickersin 1994)

#1 Influenza Vaccine/
#2 (influenza$ adj3 immuni$).tw.
#3 (flu adj3 vaccin$).tw.
#4 (flu adj3 immuni$).tw.
#5 (influenza adj3 vaccin$).tw.
#6 or/1‐5
#7 exp cardiovascular diseases/
#8 myocardial.tw.
#9 angina.tw.
#10 coronary.tw.
#11 heart.tw.
#12 cardiac.tw.
#13 cardiovascular.tw.
#14 or/7‐13
#15 6 and 14

EMBASE (at http://gateway1.ovid.com) with a standard filter for RCT (Lefebvre 1996)

#1 exp Influenza Vaccine/
#2 (influenza* near vaccin*)
#3 (influenza* near immuni*)
#4 (flu near immuni*)
#5 (flu near vaccin*)
#6 (#1 or #2 or #3 or #4 or #5)
#7 exp Cardiovascular Diseases/
#8 heart
#9 coronary
#10 cardiac
#11 myocardial
#12 cardiovascular
#13 angina
# (#7 or #8 or #9 or #10 or #11 or #12 or #13)
# (#6 and #14)