While going through the check out at the grocery store, the guy bagging my groceries stopped in the middle and started sneezing. He grabbed a tissue from his pocket and started wiping his nose. He was clearly sick. When he put away the tissue, I noticed it had streaks of blood on it from blowing his nose. Aside from catching his cold, am I at risk of catching something from his blood? Such as, if he had transferred some of the blood from blowing his nose onto my groceries, which I then unloaded into my car? My hands currently have some dried, cracked skin from the winter weather. Thanks for the help.

Welcome to our Forum and thanks for your questions.  The experience that you describe was a no risk event in terms of risk for HIV or other blood borne STIs.  HIV is very rare and there is statistically little risk that this person had untreated HIV or other STI.  In addition and more importantly, these infections are actually hard to transmit and are not transmitted by the transfer of blood (or, although not relevant to your experience, genital secretions) on one person's hands to another.  There are several reasons for this including that the viruses almost immediately become non-infectious on exposure to the environment as well as the fact that with transfers of this sort, the amount of infectious material transferred in very, very small.  In addition, the viruses do not enter the body through recent cuts, scrapes or cracks.  OTOH, the cold virus, as you note is mostly transferred through the sorts of hand to object transfers you describe.  Different viruses behave very differently.---