Journal of Vaccine Research 2024, Vol.14, No.6, 287-296 http://medscipublisher.com/index.php/jvr 289 These vaccine strains are able to trigger a strong immune response. Studies show that the measles part of the vaccine gives high and long-lasting protection, with many people staying immune for years (Davidkin et al., 2008; Prymula et al., 2021). The mumps and rubella parts also work well, although in some cases the immune response to mumps may be a bit lower (Tischer and Gerike, 2000; McLean et al., 2018). 2.4 Immune response to vaccination The MMR vaccine helps the body build both humoral and cellular immunity. After the vaccine is given, the weakened viruses in the shot start to copy themselves inside the body. This activates the immune system. B cells make special proteins called antibodies. These antibodies attack and block the measles, mumps, and rubella viruses. This is called humoral immunity. At the same time, T cells are also activated. They help find and destroy infected cells. This is called cellular immunity (Tischer and Gerike, 2000; Davidkin et al., 2008; Prymula et al., 2021). The protection from the MMR vaccine lasts a long time. One study showed that many people still had strong antibody levels 20 years after getting the vaccine (Davidkin et al., 2008). But over time, these antibody levels can go down. Because of this, booster shots may be needed to keep the best level of protection (Tischer and Gerike, 2000; Pebody et al., 2002). 3 Clinical Efficacy of the MMR Vaccine 3.1 Efficacy against measles The MMR vaccine works very well to prevent measles. Many studies show that the vaccine leads to high levels of protection. One study found that the seroconversion rate for measles was 100% in both groups of children, no matter what age they got their first dose (He et al., 2014). Another study compared two different MMR vaccines and found that children who received the "Priorix" vaccine had higher levels of anti-measles antibodies than those who got "Triviraten" (Crovari et al., 2000). These antibodies stayed at high levels, with no major drop one year after vaccination. These results show that the MMR vaccine gives strong and long-lasting protection against measles. 3.2 Efficacy against mumps The protection from the MMR vaccine against mumps can vary, depending on which vaccine strain is used. A study from Spain found that children who got the "Vac triple MSD" vaccine had a much higher seroconversion rate for mumps than those who got "Triviraten" (81.1% vs. 14.3%) (Rojo et al., 2003). This shows that the type of vaccine strain makes a big difference. Another study found that mumps antibodies dropped a lot about 10 months after the first MMR dose. But giving a second dose helped restore high levels of protection (He et al., 2014). In a large trial in Italy, the "Priorix" vaccine again showed better results than "Triviraten" for mumps, with a seroconversion rate of 97.0% compared to 35.4% (Crovari et al., 2000). These studies suggest that while the MMR vaccine does protect against mumps, the strain of the vaccine and giving two doses are both very important for getting the best protection. 3.3 Efficacy against rubella The MMR vaccine is very effective in preventing rubella. A long-term study from Finland followed children for 15 years after they received the MMR vaccine. The results showed that 100% of the children had rubella antibodies after the first shot. Even after 15 years, 99% of them were still seropositive, which means their immunity stayed strong (Davidkin et al., 2000). Another study also found that children stayed fully protected against rubella for at least 10 years after getting the vaccine (Prymula et al., 2021). These studies show that the MMR vaccine gives long-lasting and reliable protection against rubella. 3.4 Overall efficacy The MMR vaccine provides strong overall protection against measles, mumps, and rubella. In Finland, after
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