Welcome & thanks for posting your query to HCM.
In your case you have got injury
without an penetration of nail into the skin and without any blood coming out but you can see a very small wound which according to you is negligibly small. If you washed the area with soap and water or cleaned the area with a sanitizer the the chances of infection are quite less.
If you have not done above then as the nail was rusted so there is always high chance of infection even through minor abrasion. In this instance also, we need the history of your last vaccination
done for tetanus
. If it was in last 10 years of period then should not be worried about it and no vaccination is required. If it is in not done in 10 years or if you do not remember it then should be immunized within 24 hours and should not wait longer.
In future also if anybody gets any injury then it should always be thoroughly washed and cleaned to avoid the chances of any type of infection.
Do take care.
Hope the information prove to be helpful for you.
Dr Sanjay K Kanodia