The object is a visible medium through which you are expressing affection towards a heavenly person. Similarly, when you say “I love you” over the phone, it is not the phone who you are saying “I love you” to, but rather, the person, who is in that moment invisible to you.
I’m the sacristan at my parish. When I walk into the Church and it is completely empty, I will hug / kiss the cheeks, hands, and feet of the St Therese statue. I will also kiss the Immaculate Heart & Sacred Heart. I frequently kiss the holy images that I keep in my apartment, especially the face, hands, and Immaculate Heart of my mother, and even her lips (not an odd thing in traditional cultures) but also the wounds of Jesus, the image of St Catherine, St Therese, and St Joseph. Many saints were likewise highly expressive in their adoration, and I have found this to be enormously beneficial to me. The 1st century Christians greeted one another with a kiss, and this continues in many modern cultures, although regrettably American culture has a rather confused understanding of this.
Unless you have a threatened immune system as a result of a condition, worrying about hygiene is ill-advised and even counterproductive. Many 21st century people suffer from weak immune systems precisely because they go to inordinate ends to avoid germs. Eat fruit & vegetables, and avoid stress in so far as it is possible, and you will optimize your chances to be healthy. If you catch a bug, your immune system will very quickly pummel it, and it will be even further protected from those strains in the future.