So, I get my test read in a little of 12 hours. It'll be 48 hrs then since injection. However, I do have a bump (about 1cm) and some redness around it. This will be the second ppd injection for the test. I was negative the first time. What caused this? I never had TB growing up and was at a funeral over the weekend for my grandfather. I think I may have gotten a cold from there. Could the cold have affected the test in any way? Can a PPD test show very recent exposure? I am wanting to take the CNA class and I need to be tested negative for tuberculosis. I'm not worried of having the disease, I'm more worried about how much the medication will cost without medical insurance. Help please? Also, could my body have reacted negatively to the second PPD test within two weeks. I thought your body was supposed to develop antibodies within days of exposure to any foreign bacterial protein? Should I be worried here?