Some members of our household also were unfortunately affected by Peter Pan peanut butter this past week, and my 11 year old was sick for a couple days with vomiting. I hope some good comes out of the class action suits that are already underway.
Thals are generally more susceptible to infection due to lowered immune systems and also iron overload. Bacteria and viruses thrive on iron and do quite well in a high iron environment. This is more prevalent in majors and intermedias but a minor who has been erroneously treated with iron supplements over a long period can be iron overloaded just as one whose gut absorbs too much iron from the diet due to excessive bone marrow activity caused by the hemolysis (destruction of red blood cells) that occurs in some cases of minor, such as seen with Courtenay and Vincenzo in our group. I don't know if Courtenay has been checked for serum ferritin levels but Vincenzo has a serious problem with iron even though he maintains a good hemoglobin level.
Romano, there are factors as stated above that can make one more susceptible to infections in general, but it would depend on your particular cases. If you and your children tend to fall ill with colds, etc. easier than the average person it may indicate that some of these factors are at work. White blood cell counts and measurement of spleen size on an occasional basis may indicate if this is an on-going problem.