The Efficacy of Measles Vaccination: A Review of Historical and Recent Outbreaks

Recent Measles Outbreaks and Vaccine Efficacy

While the measles vaccine has proved to be effective in the past, the recent past has been characterized by sporadic measles outbreaks in different parts of the world. These outbreaks usually affect a population that may have received poor coverage in prior immunization activities because of many reasons, such as vaccine refusal, inadequate infrastructure in delivering vaccines to the targeted population, or religious or political influence on non-immunization.

A good example is the measles outbreak in Milan, Italy, that started in March and ended in August 2017. In this period, 203 were laboratory-confirmed, and there were two hospital transmissions. The occurrence was a result of poor measles vaccinations and the presence of two distinct genotypes of measles: genotype D8 and genotype B3. This heightens the need and importance of high vaccination coverage, especially among children, as well as vigilance in the implementation of surveillance measures to curtail the spread of the virus.

In Romania, the difficulties of measles control have been peculiar. The country has, however, had different large epidemics, including one extending from 1996 to 1998 that produced 33,053 reported cases and 21 deaths. Other attempts to enhance vaccination coverage, such as a national immunization campaign in 1998, have reduced the cases of measles. However, the series of outbreaks in recent years, especially for the period 2008 to 2012 shows that there are continued efforts to attain sustainable herd immunity, especially in regions with social and economic disparities together with restricted access to health care facilities.

The case of the United States also shows the great deal of balance that is required to continue controlling measles. Measles was declared to have been eliminated in the U.S. in the year 2000, but this simply refers to the failure of the virus to transmit from one person to another for more than 12 months; however, cases of the outbreak have occurred due to imported cases. For instance, in the 2014/2015 multi-state outbreak, which originated in California, the outbreak involved people who had not been vaccinated, hence the importance of vaccination in controlling outbreaks.

Vaccine Efficacy and Public Health Responses

The effectiveness of the MMR vaccine has been confirmed in practice: the first dose of the vaccine gives about 93% protection against measles, while the second dose gives up to 97%. Yet in the vaccination programs, not only the vaccine effectiveness is crucial but the coverage rates in the population as well. It is so communicable that a great degree of herd immunity is needed, usually above 95%, to avoid the spread of the disease.

Where the vaccination rates are below this level, epidemics can and do take place, which is quite evident from the current occurrence of Ebola. For instance, the outbreak of the disease in Quebec, Canada, in 2011 maintained a population immunity of nearly 95%. This outbreak comprised ninety-four cases and was characteristic in the sense that it impacted different, unrelated networks of unvaccinated persons in the population. The two examples described above are consistent with a meta-population model, which shows how local pockets of low vaccination can cause continuous transmission in otherwise well-vaccinated populations.

This is accompanied by a public health response during the outbreak, which also affects the efficiency of vaccination. For instance, quick recognition and quarantine of infected individuals, identification of contacts, and especially immunization of vulnerable groups are parts of controlling outbreaks. The identification of measles virus genotypes has been made easier through the use of the molecular technique, the real-time RT-PCR, and this has played a crucial role in being able to differentiate between actual wild-type measles fever and reaction to the measles vaccine; this has helped in avoiding unnecessary controversies such as case isolation and contact investigations.

Challenges to Measles Elimination

Nonetheless, many barriers still make it difficult to eliminate measles all over the world, even though the measles vaccine has been accredited to have a high success rate in preventing measles. The problem of hesitancy in taking vaccines is also persistent due to disinformation and lack of trust in related authorities in many geographical areas. This has been made worse by myths such as the MMR vaccine causing autism when, in actual sense, there is no scientific foundation for this.

Logistical factors also come into consideration, especially where there is weak health infrastructure in low- and middle-income countries for mass vaccination. In such settings, challenges like stock, storage, and even handling and transportation of vaccines do influence the eventual vaccination rates.

This is made worse by socio-economic measures such as poverty, precluded healthcare, and education incomprehensibleness. These lead to multiple sporadic subpopulations that are not vaccinated and are vulnerable to acquiring the disease as well as transmitting it. The problem is even worse in areas of conflict or political insecurity, where health problems can be aggravated by ineffective action or outright destruction of the public health infrastructure.

Conclusion

The history of the measles vaccine is evidence of applying vaccines to combat and possibly eradicate communicable illnesses. The decline in measles incidence and death after vaccine implementation is one of the largest success rates in the twentieth century in the sphere of public health. However, cases in the recent past are a wake-up call that measles is still very much alive and kicking. These challenges make it difficult to have high levels of vaccination coverage, which in turn are important for eliminating measles worldwide in the future.

Such concepts as vaccination have to remain crucial measures within the context of public health, both for personal and for keeping the general immunity against further evolution of the virus. From a further perspective, the experience of historical as well as recent measles epidemics would serve as the basis for the activities that continue to strive for the completion of this vaccine-preventable disease, which is highly infectious and lethal if left unaddressed.

References

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