Can introducing the finger into one's genital area after fingering pose a risk of infection?

Hello doctor,

I recently had a sexual encounter with someone I did not know well. During the encounter, I inserted one finger into their vagina. Additionally, at one point, our genitals came into contact without actual intercourse or penetration. I am feeling anxious about the possibility of contracting STIs, as this is my first experience of this kind. Could you please advise me on whether there is any risk, what the likelihood of transmission might be, and if there are any immediate steps I can take to protect myself?

Thank you.