The tests included in the Cold & Flu Rescue Kit perform best when used on people who have symptoms that are likely to be caused by the specific target microbe (virus or bacteria). Therefore, Rockdoc recommends that only symptomatic people, meaning people experiencing any of the symptoms listed HERE test themselves using the Cold & Flu Rescue Kit. If you are not experiencing any cold or flu symptoms when you use the Cold & Flu Rescue Kit, it may be less sensitive, meaning you could have a cold or flu but the test might not identify the low virus level in your body. However, if the test does report a positive result, it is likely that the result is correct and you do have the virus in your body.