400 older adults
Randomly assigned by computer into 2 groups
1
Shot with northern
hemisphere flu shot* before
winter and
shot with normal saline
before next summer
hemisphere flu shot* before
winter and
shot with normal saline
before next summer
2
Shot with northern
hemisphere flu shot*
before winter and
shot with southern hemisphere
flu shot# before next summer
hemisphere flu shot*
before winter and
shot with southern hemisphere
flu shot# before next summer
* Shot with influenza vaccine before winter seasons (Fluarix Tetra®, GlaxoSmithKline or FluQuadri®, Sanofi Pasteur)
# Shot with influenza vaccine before summer seasons (Fluarix Tetra®, GlaxoSmithKline or Vaxigrip®, Sanofi Pasteur)
# Shot with influenza vaccine before summer seasons (Fluarix Tetra®, GlaxoSmithKline or Vaxigrip®, Sanofi Pasteur)