It is recommended that the PPD skin test be administered after 14 days and the result is negative. If the skin test result is positive, tuberculosis infection needs to be ruled out before the New Crown vaccine can be given. If TB infection is present, the timing of the New Crown vaccination needs to be determined by the condition. The reasons for the 14-day interval are: 1. As a new vaccine, there is a temporary lack of data related to the PPD skin test and a 14-day interval is needed for safety; 2. Although a positive PPD skin test result (redness, swelling, and hard nodules at the vaccination site) mostly appears within 24-72 hours, a small percentage of people may have a positive result within 7-10 days. Patients who are allergic to the New Crown vaccine may also develop skin redness, swelling and hard nodules. If the interval is not enough and redness and hard nodules appear at the site of vaccination, it is not certain whether it is a positive PPD skin test result or an allergy to the New Crown vaccine. In addition, the following conditions should be noted before the New Crown vaccine is administered: 1) those who have had previous vaccine allergies should not be vaccinated; 2) those who are in the acute phase of fever or disease should not be vaccinated; 3) those who have uncontrolled epilepsy or other serious neurological diseases should not be vaccinated.