A sharp drop in platelets after the third dose of the Neocoronavirus vaccine may be an adverse reaction to the Neocoronavirus vaccine, but there are no scientific studies to confirm this. Neocoronavirus vaccine is used to prevent infection with Neocoronavirus, and it will improve the body’s immunity after injection. However, the vaccine also has some adverse reactions. Most of the adverse reactions are mild and the vaccinated person will not experience any obvious discomfort, but there are some vaccinated persons who have obvious reactions but can basically recover on their own. Platelet drop after the third injection of the new crown vaccine, general platelets can often be restored to the positive level after more than 10 days. Because platelets grow faster, more than 10 days of time the whole body platelets can be replaced once. If there is no bleeding phenomenon generally will not affect the health of the body. If the platelets decrease very seriously, it may also be caused by aplastic anemia, bone marrow suppression, severe infection, acute leukemia and other diseases. You should go to the hospital in time for examination to clarify the cause of the disease and actively treat it.