Research now tells us that maybe there was some science behind the granny's insistence. Eucalyptus oil, which is an active ingredient in Vicks, alongside Camphor which according to Wikipedia is now a synthetic version, has proven properties at dealing with virus' as this article shows.
"Owing to their lipophilic nature, EOs are advocated to penetrate viral membranes easily leading to membrane disruption. Moreover, EOs contain multiple active phytochemicals that can act synergistically on multiple stages of viral replication and also induce positive effects on host respiratory system including bronchodilation and mucus lysis."
What this means is that certain essential oils (EOs) can breakdown the wall of a virus, and that they can work on stopping the virus replicating itself, whilst having a positive effect on the tubes in the breathing apparatus, the trachea, bronchus, bronchioles and lungs and the breakdown of mucus.
Like most non-money making products for the pharmaceutical companies, eucalyptus oil hasn't been given any media coverage as a way to help yourself, should you catch a virus, of any description, but I leave it with you, if you are looking for ways to help you deal with seasonal virus', that eucalyptus essential oil might be handy to have in your toolkit.
Coincidentally Vicks was originally developed as an ointment for arthritis gout and neuralgia, and in recommending it to people for this purpose, they received feedback that it was clearing people's sinus' too. It is recognised in the field of aromatherapy as being an EO that is useful in cases of rheumatic pain.