Journal of Vaccine Research 2024, Vol.14, No.6, 287-296 http://medscipublisher.com/index.php/jvr 290 starting a two-dose MMR vaccination plan, the country was able to stop the spread of these diseases completely (Davidkin and Valle, 1998). This real-world success proves how well the vaccine works. The vaccine also helps prevent serious cases that need hospital care. One study showed that the MMR vaccine reduced hospitalizations for measles and mumps by 90%. The hazard ratio for these hospitalizations was 0.10, which means a much lower risk for vaccinated people (La Torre et al., 2017). There is also some research suggesting that the MMR vaccine might help reduce the severity of COVID-19 symptoms, showing possible cross-protection against other viruses (Table 1) (Fedrizzi et al., 2021). Table 1 Hospitalizations for measles and mumps, all infectious diseases and respiratory diseases for all MMR vaccine doses (Adopted from La Torre et al., 2017) Vaccine Measles N (%) Mumps N (%) Measles and MumpsN(%) All infectious diseases N (%) All respiratory diseases N (%) Nodose 9 (0.4) 1 (0.04) 10 (0.4) 262 (11.4) 424 (18.4) 1 dose 3 (0.06) 1 (0.01) 4 (0.1) 82 (1.5) 202 (3.7) 2 doses 0 (0) 0 (0) 0 (0) 70 (2.1) 183 (5.5) Total 12 (0.1) 2 (0.01) 14 (0.1) 414 (3.8) 809 (7.4) p <0.001 Ns <0.001 <0.001 <0.001 The MMR vaccine has clearly helped lower sickness and death from these three diseases. High rates of long-lasting immunity have greatly cut down the number of cases. The success in Finland, where measles, mumps, and rubella were eliminated after using the vaccine, is a good example of its power to control these diseases (Davidkin and Valle, 1998). The vaccine also helps reduce hospital stays for infections, including some lung diseases, which shows its wider health benefits (La Torre et al., 2017). Overall, the MMR vaccine has played a key role in improving public health and lowering the burden of these diseases worldwide. 4 Factors Influencing the Efficacy of the MMR Vaccine 4.1 Vaccine coverage and immunization strategies The success of the MMR vaccine depends a lot on how many people get vaccinated. High coverage is very important to stop the spread of measles, mumps, and rubella. For example, in Finland, a two-dose vaccine program with 97%~98% coverage helped fully eliminate these diseases (Davidkin and Valle, 1998). On the other hand, if not enough people get the vaccine, outbreaks can still happen. Low coverage reduces herd immunity and makes the vaccine less effective at protecting the whole community. 4.2 Individual differences and immune response The body’s response to the MMR vaccine can be different from person to person. Age, nutrition, and immune health all play a role. Some studies show that giving the first dose at 8 months of age can work just as well as giving it at 12 months (He et al., 2014). This means there is some flexibility in when the first dose can be given. Children who are malnourished or have weak immune systems may not respond as well to the vaccine. These children might need special vaccination plans to make sure they get enough protection (Lalwani et al., 2015). 4.3 Impact of viral variants Different virus strains can affect how well the vaccine works, especially for mumps. Some studies found that children who got the MMR vaccine with the Urabe mumps strain had better antibody levels than those who got the Jeryl Lynn strain. This shows that the type of virus strain used in the vaccine matters. Because of this, it is important to keep checking for new virus variants and update the vaccines if needed. 4.4 Need for booster doses Studies show that getting more than one dose of the MMR vaccine gives better long-term protection. For example, in a 10-year study, children who got two doses of the MMRV vaccine stayed protected against varicella
RkJQdWJsaXNoZXIy MjQ4ODYzNQ==