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Whooping cough used to infect hundreds of thousands of people in the U.S. and kill thousands of children every year. Join us as we learn about the women who developed the vaccine that has since saved thousands of lives.

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Back in the early 1930s in the US, about 200,000 cases were reported every year, of a disease that today is considered rare, and easily preventable. 
Pertussis, also known as whooping cough. 
It’s a highly contagious, airborne disease, caused by Bordetella pertussis, a bacterium that attaches to the lining of the lungs and releases a toxin, damaging lung tissue and causing inflammation. 
The inflammation causes a rapid, painful, and severe cough that forces the air out of your lungs, until you inhale with a big, long ‘whoop’, giving the disease its nickname. 
Pertussis is particularly dangerous to infants under two, and until there was a way to prevent it, it killed up to 6,000 children every year. 
But there are ways to prevent the disease today, thanks to the work begun 80 years ago by Grace Eldering and Pearl Kendrick, two women who used their training in science to develop the first whooping cough vaccine.
And they did it in their spare time.
Kendrick and Eldering met while working at a public health laboratory in Grand Rapids, Michigan. 
Both women were college educated, but they came from pretty different backgrounds -- Kendrick had studied bacteriology and worked at public health labs in New York, before being appointed the director of the Michigan Bureau of Laboratories in Grand Rapids in 1926.
Eldering was a small-town schoolteacher from Montana, who came to Michigan looking for work.
But both had demonstrated intelligence and ambition, which allowed them to find work in public health, a field known for hiring women at the time, because money was tight in Depression-era America, and women were paid less than men.
Another thing that Kendrick and Eldering had in common: they had both had, and survived, whooping cough as children, an experience that shaped their professional lives.
So when Grand Rapids saw a pertussis outbreak in 1932, Kendrick and Eldering wanted to help.
But the lab’s director would only let them work on their ideas after they’d finished their usual tasks -- mostly testing water and milk samples. 
Although their eventual goal was to create an effective pertussis vaccine, Kendrick and Eldering realized that they’d need to learn more about the bacteria first.
So after the lab closed every day, Kendrick and Eldering went out into Grand Rapids, visiting the families of sick children and collecting samples on what were known as cough plates.
The cough plates were basically what they sound like: just petri dishes you hold, like, 10 to 12 centimeters from the child’s face, and they cough on it. 
With any luck, some mucus would land on the plate, and if it contained any pertussis bacteria, then little colonies would start to grow. 
At the time, the main thing they wanted to do was just find a way to rapidly cultivate these colonies, so doctors would have a way to diagnose the disease earlier and isolate contagious patients.
Because, back then, doctors often weren’t able to diagnose the disease until an ordinary cough grew into a “whooping cough,” by which time it was pretty much too late. 
Plus, all these cough plates would help Kendrick and Eldering figure out how long pertussis was contagious based on whether, after a certain amount of time, children were still coughing up enough bacteria to form colonies on the cough plates.
At the time, the standard growth medium on cough plates was fairly well established: a mixture of potato juice and blood did the trick.
Potato juice might seem like a strange way to grow bacteria, but it was there to counteract the effects of the fatty acids in mucus, which is actually pretty good at inhibiting bacterial growth.
By providing pertussis-friendly nutrients, as well as starch to absorb the fatty acids, the potato juice helped the bacteria grow.
More importantly, the blood provided material where the pertussis bacterium could really leave its mark -- B. pertussis produces a toxin that rips apart red blood cells. After 3 to 6 days, the reaction can be detected under a microscope, allowing for quick confirmation of whether pertussis is present. 
Kendrick and Eldering decided to use sheep’s blood instead of human blood, because sheep’s blood was much easier to come by, and it worked just as well.
With this test in hand, Kendrick’s lab spread the word to local doctors that they could send in cough plates to be tested for pertussis.
With the hundreds of cough plates they collected, they were able to better understand the mechanics of the disease. For instance, they realized that, during the first 3 weeks of infection, a patient’s cough contained enough bacteria to infect others. 
But after four or five weeks, most patients were noninfectious. 
This allowed Kendrick and Eldering to establish the first science-based guidelines for quarantining whooping cough patients. 
Before this, there had been quarantines, but they varied anywhere from two to four weeks, which Kendrick’s lab showed was much too short. So the Grand Rapids health department enforced a quarantine of 35 days after the onset of symptoms, or two negative cough plates in a row within 28 days.
For Kendrick and her cohorts, the next step after figuring out how to contain the outbreak was finding a treatment. They wanted a vaccine. 
A few attempts had been made to develop a pertussis vaccine, but none of them seemed to work.
But new research out of the Netherlands at the time suggested that a whole-cell vaccine might be the answer. 
In this scenario, scientists could cultivate the bacteria and kill it with chemical compounds like thiomersal or formalin. They’d inject the bacteria into a patient, but because the bacteria were dead, they couldn’t actually infect the patient. 
But the process would still allow the patient’s immune system to develop antibodies for pertussis, so if they were ever exposed to it again, they’d be able to fight back.
The lab began producing autogenous vaccines, which were made for each individual patient, upon request from their doctor, and prepared using that patient’s specific strain of the bacteria. 
But after several months of handling requests, one by one, for autogenous vaccines, Kendrick appealed to her boss for permission to begin crafting a general vaccine made from several local, recurring strains of pertussis. 
Sure, her boss said, and this is a quote, “Go ahead and do all you can with pertussis if it amuses you.” 
So they set to work.
Using the whole-cell method and a mix of several local strains of the bacteria, Kendrick and Eldering began testing a general vaccine on animals -- and themselves -- to make sure it was safe. 
After successfully concocting a general vaccine, they needed to test it in the field, rather than just in the lab. So they launched a city-wide field trial in Grand Rapids to find out if the vaccine actually worked. 
This was problematic for two reasons. In the early 1930s, there were no accepted standards for a vaccine field trial. No playbook. Also, it was the Great Depression, so money was scarce.
Kendrick and Eldering cobbled together funding from federal emergency funds, the local health department, and private donors.
They devised a plan wherein over a thousand pre-school aged children would be split into two groups: an experimental group that the lab would inoculate, and a control group that wouldn’t be inoculated.
The experimental group consisted of children from parents who volunteered to have them vaccinated at local health clinics. They were given a series of 4 to 5 injections of the vaccine. 
A volunteer nurse would then visit the child every 3 to 4 months to collect cough plates and see whether or not they had contracted pertussis. The nurse would also collect cough plates from children in the control group who were not inoculated.
In October of 1935, Kendrick and Eldering presented their findings. 
Of the 1,592 children in the field trial, 880 made up the control group and 712 were vaccinated. And while there were 45 cases of pertussis in the unvaccinated control group, there were only 4 among the children who were given the vaccine, and those were mild cases.
It was the first time a pertussis vaccine seemed to work!
The federal government subsidized a follow-up study in 1938, in which children were given a smaller dose of the vaccine -- 3 shots instead of 4 or 5. The study was just as successful as the first field trial, and soon thereafter, the Michigan Department of Health began mass-producing the vaccine. 
By 1940, it was available nationwide. 
Throughout the 1940s, Kendrick and Eldering continued to improve the vaccine with the help of Loney Gordon, an African-American dietitian who couldn’t get a job in Grand Rapids until Kendrick hired her.
Gordon examined thousands of cough plates, looking for a more virulent strain of pertussis to make the vaccine even more effective. 
The three bacteriologists also worked to standardize the vaccine, developing new tests to check the concentration of any sample.
Now, the whole culture vaccine wasn’t perfect. It sometimes gave children fevers and convulsions. These days, we use a different vaccine to avoid those side effects. 
But in 1934, when Kendrick and Gordon first started testing the vaccine, 209 out of every 100,000 people got pertussis every year. In 1948, as vaccinations improved and became more popular, that number went down to 51 out of every hundred thousand. 
By 1960, it was less than ten. 
It was the first pertussis vaccine that was really effective, and those people saved thousands of lives.
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