Mass vaccination is a public policy effort to vaccinate a large number of people, possibly the entire population of the world or of a country or region, within a short period of time. This policy may be directed during a pandemic, when there is a localized outbreak or scare of a disease for which a vaccine exists, or when a new vaccine is invented.
Under normal circumstances, vaccines are provided as part of an individual's medical care starting from birth and given as part of routine checkups. But there are times when there is a need to quickly vaccinate the population at large and provide easy access to the service. When this occurs, temporary clinics may be established around communities that can efficiently handle the many people within at once.
Challenges of a mass vaccination effort include vaccine supply, logistics, storage, finding vaccinators and other necessary staff, vaccine safety and public outreach.
Historic mass vaccinations Measles Measles is a viral infection known for its highly contagious properties. Infection with measles is transmitted through the respiratory tract and can manifest as fevers, the "three C's of measles": cough, coryza (runny nose), conjunctivitis(red/watery eyes), and a maculopapular rash. Prevention can be achieved with vaccination, as a single dose is 93% effective against measles and both doses of the two-shot series provides 97% effectiveness against measles. Management of measles, not prevention of measles, can be accomplished with vitamin A supplementation.
Measles History
Measles was first described by physicians in the 9th century. In the centuries after, as explorers traveled from their borders and encountered new populations, these previously unexposed groups were acutely effected by measles. It wasn't until 1757 that Francis Home discovered the cause of measles to be as a result of infection from a pathogen. Deaths from measles dropped by the 20th century due to advances in medicine and standards of living, though this improvement was largely seen in developed nations. Globally, there is still a documented yearly occurrence of 2 million deaths from 30 million cases.
Vaccine Development John Franklin Enders developed a live measles vaccine which underwent testing from 1958 to 1960, followed by public licensing in 1963. The vaccine used in the United States since 1968 was a vaccine developed by Maurice Hilleman, which is a weaker live vaccine and showed increased efficacy, leading to a more effective measles vaccine. In 1971, the Measles vaccine began to be produced as a combined vaccine with two other newly developed vaccines: mumps and rubella (MMR Vaccine). In 1989, the two-dose regimen of the MMR vaccine began due to improved immunity developed from two doses rather than one.
Measles Eradication Efforts
Under the Vaccination Assistance Act of 1962, President John F. Kennedy directed federal money to states in an effort to provide affordable and effective vaccinations to children and the broader population. By 1965, President Lyndon B. Johnson worked with Congress to extend the Vaccination Assistance Act to cover Measles. In 1967, Johnson and the CDC set out to eradicate measles and saw a drop in weekly measles cases from 1,000 to 200. Cases of measles dropped in 1968 with 22,000 cases compared to 450,000 cases per year prior to the advent of the vaccine. Following an uptick in cases in the early 1970s President Jimmy Carter set a goal for 90% vaccination, achieved partly through school mandates. This found success, with 96% of school children being vaccinated by the end of his term in 1981 and a record low number of cases: 2,600. Through the 80's and early 90's, vaccination hesitancy picked up steam. This was met by President Bill Clinton with the Comprehensive Child Immunization Act of 1993. By 2000, the last full year of his second term, the United States officially declared measles had been eradicated.
Barriers to Efforts
As with any mass vaccination effort, vaccine-hesitancy remains a major barrier to maintaining low levels of measles cases. A key cause of this challenge was a research article written in 1998 in "The Lancet" claimed to show a link between autism and the MMR vaccine. In the wake of the article, negative news coverage of the MMR vaccine increased along with vaccine skepticism. "The Lancet" retraced the paper in 2010 for incorrect data resulting from the study and for unethical treatment of the children in the study. Due to the high infectivity rate of measles, the vaccination level to reach 'herd immunity' is 95%. However, anti-vaccination campaigns and misinformation has caused the vaccination level to dip below the threshold, leading to a rise in measles cases in the USA. Despite previously declaring measles had been eliminated in the US, there is now a Measles resurgence in the United States.
Smallpox Early successes in eradication (prior to 1950) In 1947, after a man traveled from Mexico to New York City and developed smallpox, Dr. Israel Weinstein announced to the residents of New York the need to get vaccinated. Vaccine clinics were established throughout the city and within less than a month, 6,350,000 residents were vaccinated. This was enabled by improvements in vaccine production and storage. Prior to new developments, transportation represented a major issue and hindered mass vaccinations. Because smallpox vaccination requires a live virus, it originally required a sample to be transferred from person-to-person or animal-to-person directly. The creation of a liquid vaccine stored in capillary tubes marked a major advancement for the smallpox vaccine. This method involved the use of glycerol as a preservative and was significant for storage and transportation. In addition to these benefits, it enabled mass production through the use of animals, and ensured long term viability at temperatures below freezing. However, this method was insufficient to enable widespread vaccination in tropical regions of the world, and thus was largely restricted to temperate countries. Compulsory vaccinations were used throughout the beginning of the 20th century in a most of these countries, which led to the decline of smallpox. For countries such as the United States, Canada, the United Kingdom, and some other European countries, outbreaks were quickly shut down by strong public health policies. Soon, the more deadly Variola Major smallpox variant steadily declined, and endemics were only brought on by travelers from countries that lacked control over smallpox outbreaks. It's important to note that the milder Variola Minor smallpox variant remained prevalent until the mid-20th century, as it often didn't warrant hospital visits or was misdiagnosed. The success of health policies in controlling and eliminating smallpox by the 1950s in many countries led some to believe that the world eradication of smallpox would be possible.
Interest in worldwide eradication (1950-1959) The creation of a heat stable, freeze-dried vaccine occurred in the 1950s. Further improvements in freeze-drying technology allowed for the mass production of the vaccine at a commercial level. The Health Assembly, a group within the World Health organization (WHO), began discussing the possibility of eliminating smallpox between 1950 and 1955. The idea was ultimately rejected, as many viewed it an impossible task to take on. In 1958, a professor from the USSR, acting as a Health Assembly delegate, once again pushed the idea of smallpox being an issue for all countries, whether or not endemics are still occurring. He presented a report to the Eleventh World Health Assembly, which argued that world eradication of the disease is possible, as shown by the success of countries that managed to eliminate it through health policy. This was particularly significant as the professor, Viktor Zhdanov, had come to the conclusion on his own, without knowledge of arguments from previous World Health Assemblies. In this Zhdanov Report, he used the USSR as an example, arguing that the success of mandatory vaccinations throughout his country proves that it's possible to eliminate it in any country. Zhdanov offered the support of the USSR, and backed the legitimacy of the report through the donation of millions of vaccines and previous offers of support to central-Asian countries. The method of eradication would that was proposed involved the use of the newly developed freeze-dried vaccinations and mandatory vaccination. Surveillance containment programs was also mentioned, which actually came to dominate in the later years of the eradication campaign. Over the course of the next year, resolutions coordinating the start of the program, as well as to ensure the success of it, were made. During the Twelve World Health Assembly in 1959, the proposal of an eradication campaign for smallpox was voted for successfully.
Smallpox eradication program (1960-1966) The eradication of smallpox seemed to be easier and less costly than other previously eradicated diseases. Smallpox had no vectors, as humans were the only reservoirs carrying the disease. Furthermore, the elimination of the disease would be mostly on mass vaccination and did not require vector control. Directed by Donald Henderson, this first effort involved the use of mass vaccinations with a goal to have 80% of every country's population immunized. Although the program was brought forth by WHO, implementation would largely depend on individual governments. WHO would be responsible for supporting the programs through vaccine production, and training of staff. Each country would be required to cover most of the costs and actual functions of the program. A lack of universal commitment from countries hindered this campaign allowing smallpox to remain prevalent almost a decade later. This was particularly a problem in developing countries. The WHO was not designed to provide considerable material support and close collaboration between countries on a wide scale. Over the first few years of the program's initiation, a lack of donations of vaccines and money hindered the success of the program. The WHO created the Expert Committee on Smallpox in 1964 due to the lack of progress. A report was released giving a more clear strategy to be implemented, in the form of different phases. Based on outbreaks that occurred in India in regions that claimed to have more than 80% vaccination rates, the committee determined that 100% of the population would need to be vaccinated in the first mass vaccination phase. After this, they would focus on stopping subsequent cases and investigating them. This was not well received during the Seventeenth World Health Assembly, in which many express doubts over the success especially with extreme vaccine shortages following a lack of donations. It wasn't until 1965 that the USA increased commitment to the cause, yet not out of interest but because they were already starting a measles eradication campaign and felt this could be added on. This along with continued support from the USSR led the WHO to develop an intensified program for smallpox eradication, however many members still lacked confidence in this new program's success.
Intensified smallpox eradication program (1967-1980)