The influenza vaccine is unusual in that most years a different vaccine is made. Because strains of influenza virus that circulate in the community can differ from one season to the next, the vaccine must change to best protect against those different strains.
In VMware, switches are used to establish a connection between the virtual network and the physical network. With ESX and ESXi, two different kinds of switches can be used: standard switches and distributed switches.
It is aware of the MAC addresses of all virtual network adapters attached to it. An external virtual switch also knows about the MAC addresses on any layer-2 networks that it has visibility to via its assigned physical adapter or team. The Hyper-V virtual switch does not have any native routing (layer 3) capability.