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Thanks for your question.
It is good to know that she is not having any cold symptoms at this time. From the time of infection to the development of symptoms is called as incubation period and in the case of common cold it could be somewhere between 37 to 72 hours. Now the next important point is that it is not mandatory to develop cold after kissing.... odds of transmitting infection in this way is low, but possible. These kind of infections are common during early childhood and in a person with a weak immunity, but as you become adult,,,, these infection become less frequent and you immunity play a significant role in it. There are 100 different viruses that can cause common cold, once you recover from one type of infection, your body is immune to that specific virus, and you never catch the same virus again as you are protected. This might be a case as well for not developing symptoms at all after three days.
The last point is that most of these common colds are harmless and tends to subside on its own without any specific treatment. Since she does not have any symptoms, no treatment is required at this time. Please let me know if you have any specific question for me.
So you're saying that open-mouthed kissing is a low-risk activity, as far as transmission of the common cold is concerned?