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In 2000, the Pan-American Health Organization announced a monumental public health achievement: Widespread vaccination efforts, overseen by the Centers for Disease Control and Prevention, had effectively eliminated measles from the United States.
The Disease Previously The vaccination period in the US each year affected 3 to 4 million people and was now isolated to minor, restrained outbreaks associated with international travel.
This year's record breakout threatens this achievement.
Since January, over 700 cases of measles have been reported in 22 states. Most sufferers were never vaccinated. Sixty people were hospitalized and caseload numbers continue to rise, although in some regions, such as the Pacific Northwest, the outbreaks have subsided.
Although the number of cases is dwarfed in the first half of the 20th century, they are still significant, says René Najera, epidemiologist and publisher of the vaccine training website for the history of vaccines.
"We are nearing a turning point and if the cases continue to escalate, the US could lose its elimination status," says Najera.
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A disease is considered eliminated from a country if it can not be contracted within its limits, although cases linked to international travel, as occurred since 2000, may still occur.
Losing the excretory status would be a failure of one of the greatest achievements of public health in our history.
Prior to the 1960s, "Measles was basically a universal childhood experience," says James Colgrove, a health historian at Columbia University University.
Essentially everyone has understood it. Of the millions infected annually, 400 to 500 would die, tens of thousands would be hospitalized, and hundreds, according to the CDC, would face serious complications such as encephalitis.
"People had experienced the damage that measles could do, and so when the vaccine came out, they were open-minded," says Najera.
The first steps towards measles vaccine were made in 1954, when John F. Enders and dr. Thomas C. Pebbles in Children Cervical smears and blood samples collected a Boston school that had just experienced an outbreak.
Enders and his laboratory succeeded in isolating, cultivating, and eventually adapting the measles virus to chick embryos, eventually leading to the release of a vaccine in 1963. In 1968, a more effective vaccine was developed by Maurice Hilleman and his colleagues. and is the same measles vaccine (combined with a mumps and rubella vaccine) that is used today in the US.
"The measles vaccine has been widely accepted and welcomed," says Najera. Between 1964 and 1974, the number of measles cases in the United States declined. During this time, states began enacting laws that require proof of vaccination to register at public schools. "These types of laws have helped drive the vaccine effort," says Colgrove.
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In 1978, vaccinations were so good that the CDC set itself the goal of eliminating measles from the USA by 1982. Amesh Adalja, a Johns Hopkins physician and infectious disease expert At the university, it is stated that achieving excretion requires "herd immunity" or a level of immunity in a population where the likelihood that vulnerable individuals (such as infants or at-risk) may be reduced Virus is extremely low.
"Measles are one of the most contagious infectious diseases, which means you need more than 93 percent immunity to protect a population," says Adalja. "One dose of vaccine was not quite enough."
In 1989, the number of measles increased to 18193 cases, of which about 40 percent occurred in vaccinated children. After this outbreak, public health officials recommended two doses of measles vaccine. This recommendation worked in conjunction with increased efforts to vaccinate low-income communities. The rate of measles continued to decline, so that in 2000 the Pan-American health organization was able to explain the elimination of the disease from the US.
"It has been a tremendous achievement in the field of public health, especially because measles are so contagious," says Colgrove.
Of course there have been measles outbreaks in recent years, but all come from international travel. In 2014, 383 cases were reported in Amish, Ohio, with low vaccination coverage. Two Amish men returned from typhoon aid in the Philippines and unknowingly returned the virus, fueling the outbreak. In 2015, an outbreak occurred in Disneyland, where 147 cases were thought to have come from a traveler from the Philippines.
Every outbreak since eradication was eradicated when the virus hit the wall of the herd immunity and maintained the elimination status of the USA.
But now public health officials fear that the exclusionary status as measles could crack a comeback. "If things do not change, we could be back in the United States, where measles will not be eliminated," says Najera.
That would not mean that the US would affect 3 to 4 million people every year. Vaccinations are high enough to prevent this. Outbreaks, however, would become more common.
Unvaccinated young children are at the highest risk of dealing with measles and developing rare but serious complications from the disease.
"Statistically speaking, as soon as we have over 1,000 cases of measles, we will have death," says Najera. "For a completely preventable disease that's unacceptable."
"We're not there yet, but we're getting very close," he tells Najera "If these numbers continue to rise and new cases emerge , which are not related to foreign travel, we are there. "
Most cases in the current outbreak are related to travel, but Adalja says the longer the outbreak lasts The more difficult it is to attribute each case to an introduction by a traveler. As the outbreak is simmering, there is concern that the domestic reservoir of measles is growing so that vulnerable people can experience infection within our borders.
According to Adalja, the US could reach this point within a few months. "If this outbreak chain burns for a year, we could question the elimination status," he says. The cause? Impfverweigerung.
"We did not threaten to lose our excretory status before vaccination refusal rates rose," says Adalja. "Due to the inactivity of certain people, they have returned measles, which are completely preventable outbreaks." The state's MMR vaccine coverage varies from 85 percent in Missouri and 98 percent in Massachusetts to 2017 data from the CDC. And some local communities have even lower rates.
Najera says states and local governments should take action now. Many already have. On April 9, the New York Health Commissioner ordered that all unvaccinated people living or working in Brooklyn be vaccinated or face a $ 1,000 fine. On April 19, a judge upheld the order. State legislators are currently considering bills to lift personal exemptions for the measles, mumps and rubella vaccine.
"If we do everything we can to vaccinate people, we could limit this outbreak," says Najera. "But we are not there yet."
"The 200-year history of vaccines has shown that maintaining a high level of immunity is always a challenge as every vaccine program will inevitably be a victim of its own success," says Colgrove. "The better vaccines work, the more people believe 'They do not need them anymore.'
Jonathan Lambert is a freelance science journalist based in Washington, DC. You can follow him on twitter @ evolambert