New Crown test strip results may change after a few hours because New Crown test strips have an expiration date for use, and too much time may invalidate the results. After using the new coronavirus pneumonia test strips, the test taker can determine whether his/her test result is negative or positive by looking for the horizontal bars at the C and T marks on the test strip. Usually, the test strips have an expiration date, and due to environmental factors, the expiration date is usually around 15-30 minutes, so results may not be accurate or may change if the test strips are viewed after a few hours. If there are two bars on the test paper after the test, the test taker should carry out nucleic acid test, blood test and other tests in a timely manner, so as to ascertain whether there is a false positive situation. In the use of test strips after the test, if the detector subsequent fever, cough and other symptoms, still can not rule out the impact of the new crown, should be timely to the hospital for consultation, to avoid further development of the situation. [Tip] This article refers to “new coronary pneumonia, new coronary virus pneumonia”, etc., has been December 26, 2022, the National Health Commission issued a notice to change the name to “new coronary virus infection”.