Currently, there are two general types of vaccines for preventing pneumococcal pneumonia. One type is the 23-valent vaccine, suitable for high-risk populations over two years old. The other type includes the 7-valent or 13-valent vaccines, which are for preventing pneumococcal infections in infants under two years old. Infants under two usually follow a "three plus one" vaccination regimen, which involves three primary immunization doses with at least one month between each dose, followed by a booster shot. Additionally, adults over two years old or other high-risk groups are advised to take the 23-valent vaccine, which requires only a single dose. However, those who are frail or have poor immune responses may need a second booster dose five years after the initial vaccination.