I recently learned about Pearl Kendrick and Grace Eldering, two fearless women who helped stop one of the world’s most deadly infectious diseases. Both were from Grand Rapids, Mich., and they may be two of the most underappreciated women in science and medicine. They developed an improved vaccine to prevent pertussis (whooping cough) and in doing so saved countless lives.  Both were featured in the March issue of the Smithsonian magazine.


Pertussis is a highly contagious bacterial illness characterized by paroxysmal cough, vomiting and an inspiratory whoop. Pertussis can also occur as a mild or moderate cough illness in persons who are partially immune.  

The genus Bordetella contains the species B pertussis and B parapertussis, which cause pertussis in humans. Other members of the genus are B bronchiseptica, causing respiratory disease in various animals and occasionally in humans, and B avium as well as B hinzii, which cause respiratory disease in poultry and are very rarely found in humans.

Bordetellae are characterized by culture characteristics, biochemical tests and nucleic acid analysis. Some of them show reversible antigenic modulation under certain culture conditions and they mutate through several antigenically distinct phases when grown on agar.


The bacteria colonize only ciliated cells of the respiratory mucosa, and they multiply rapidly. Pertussis spreads readily from person to person by droplets the result of coughing or sneezing or when spending a lot of time near one another where you share breathing space.


Pertussis or whooping cough has been given many names over the centuries. It was first recognized in the Middle Ages and since then various epidemics have been described. Jules Bordet and Octave Gengou isolated Bordetella pertussis in Paris more than 100 years ago, which created an excellent opportunity to invent a vaccine. In 1914, the whole-cell pertussis vaccine was invented, but it suffered from lack of follow up data and proof of safety and efficacy.

Kendrick And Eldering’s Vaccine

When Kendrick and Eldering began work on a pertussis vaccine the previous development had been a rudimentary, cooking without recipes enterprise.  Their vaccine consisted of whole-cell Bordetella bacteria killed with a common antiseptic, purified, sterilized and suspended in a saline solution.  

Others who had developed vaccines before them often neglected to provide critical information on preparation, dosage and other considerations, with the result that one batch could vary wildly from the next.  

The two developers took a far more systematic and scientific approach at every step, from the initial collection of bacteria through testing whether their vaccine actually protected children.  Kendrick and Eldering learned as they went, for example, that bacteria collected at a certain stage were far more likely to elicit a strong immune response and they tested various iterations of the vaccine for safety by injecting them into experimental animals, and remarkably on themselves.  

Designing the clinical trial was the hard part, as neither had prior experience.  According to Smithsonian, Kendrick and Eldering persevered in their belief that a successful vaccine could be made, and finally developed a method to  make it.  They engineered a clinical trial using novel techniques to prove their point and basically laid the pathway for modern pertussis vaccination.

 A successive decrease in the incidence of the disease has since been observed. The vaccine has been about 80% effective in preventing serious disease and death from pertussis. The disadvantage is that the vaccine offers protection for only  five to 10 years after the last dose of the full vaccination course.

The second issue is the question of how to prevent side effects of the whole-cell vaccine. In the 1990s, the acellular vaccine –  with just a few of the original 3,000 or so antigens – was introduced in the U.S. and it gradually replaced the whole-cell vaccine.

About 10 years later, a possible failure with the new vaccine was noted in that it lacked long-term protection. Now, both vaccines are used, with the acellular vaccine being vastly predominant in most developed countries. Pertussis incidence has increased since the 1980s, but new prevention strategies include booster doses for specific age groups.

After Kendrick’s death in 1980, one of her colleagues estimated the number of lives saved by the pertussis vaccine in the hundreds of thousands in the U.S. alone.  By now, it is probably in the tens of millions worldwide.  Kendrick and Eldering’s sole intention was to save children’s lives.  

Having achieved that, they were content to be forgotten.  They even declined to have their names associated with the vaccine in contrast to the Salk polio vaccine.  

Both Kendrick and Eldering disproved on the notion as there so many other people involved in the development. Both had an opportunity to appear on an NBC show in the 1970s – that was highlighting feminist’s overlooked scientific contributions – but they politely declined.

Final Thoughts

Undervaccination in poor and middle income countries has allowed the disease to persist there, killing an estimated 160,700 people each year.  The death toll is likely to get worse as at least 23 million children are unvaccinated.

Max Sherman is a medical writer and pharmacist retired from the medical device industry.  His new book “Science Snippets” is available from Amazon and other book sellers. It contains a number of previously published columns.  He can be reached by email at  maxsherman339@gmail.com.