A person should not touch a part of their body that is usually covered, such as their feet, or scratch their head during a meal. If they have, they should wash their hands again, but there is a question whether the brachah al netilas yadayim needs to be repeated. The same question applies to a bathroom break in the middle of a meal. According to the Alter Rebbe in his siddur, the halachah is that one should say the brachah of al netilas yadayim but without Shem uMalchus, without saying Hashems Name. If a person has touched a covered part of their body during a meal with bread in their mouth, they should not swallow it before washing their hands again first. However, a light touch of the hair from above in areas that are not usually covered does not pose a problem.