Most vaccines have the same medication for the third and second shots, such as the New Crown and Hepatitis B vaccines, but there are some vaccines that have different medications for the third and second shots. New Crown third and second shots are the same in terms of composition, dosage form, and dosage. There are three types of New Crown vaccines: adenovirus vector vaccine, inactivated vaccine, and recombinant protein vaccine. The adenovirus carrier vaccine is close to natural immunogenicity and one injection is sufficient for basic immunization; the inactivated vaccine requires two injections for basic immunization; and the recombinant protein vaccine requires three injections. All three doses of the hepatitis B vaccine are the same and are administered at different times, with a thirty-day interval between the first and second doses and a five-month interval between the second and third doses. Repeatedly stimulating the body’s immune system with the Hepatitis B vaccine causes the immune cells to produce immune proteins that protect the body. Different types of vaccines are different in terms of their production processes and immunization procedures, but they have all undergone rigorous clinical trial evaluation and strict review procedures, so they all have a good safety profile and are able to produce a good immune effect after the full course of vaccination.