It has a certain effect.

2. What is the function of the first dose of COVID-19 vaccine?

According to the data obtained so far, COVID-19 vaccine generally produces antibodies in vivo within 7 days after the first injection, and the antibody positive rate in vivo can reach about 60%-90% within 14-28 days, so even if it is injected only once, it can play a certain protective role. However, after the second dose of COVID-19 vaccine, the positive rate of antibody in vivo can reach more than 90%, which can protect human body continuously. Therefore, the recommended immunization program for COVID-19 vaccine is 2 doses.