Vaccine Research in Young Children and Pregnant Women: A Lesson from History

You may be hearing a lot in social media from people claiming that the COVID-19 vaccines of Pfizer-BioNTech and Moderna, and others such as Janssen (Johnson and Johnson), AstraZeneca/Oxford, and Novavax, have not been tested enough to warrant their use in pregnant women, or in children, including young children. Such claims ignore the fact that all of the vaccines at issue are approved for use in particular countries following extensive clinical testing. In the case of the United States, we are talking about Pfizer-BioNTech, Moderna, and Johnson and Johnson as being approved as of the writing of this post in mid February, 2022, and Novavax gearing up for possible emergency use authorization by the US Food and Drug Administration (FDA). The claims about safety also typically ignore the magnitude of the danger of the pandemic that we face. To illustrate how the balance of risk versus benefit must be assessed, let’s take an historical perspective. Let’s take a trip back to the 1950s, an era, asked about the biggest worries that they have regarding their children, so many parents would instantly come up with one response:

Poliomyelitis, known commonly as polio, or infantile paralysis.

Parents were worried that their children might become gravely ill from the polio virus and end up disabled or dead. Often, as a result of poliovirus infection, people would be unable to breathe adequately, so they would be put into machines called iron lungs. During epidemics of polio in the mid 20th century, hospital wards would be full of these iron lung devices, each with a patient inside. So frightened were parents of polio epidemics that they commonly kept their children away from public places, such as swimming pools and parks during the summer.

But meanwhile, a medical scientist, Dr. Jonas Salk, had developed a vaccine against the virus. After testing the vaccine on about 700 children in Pittsburgh, Salk declared that the vaccine was both safe, and effective. His data showed that the vaccine would  save lives and prevent suffering, so he was asking health authorities to begin distributing the vaccine widely. Parents around the United States meanwhile were following the story, many of them very eager to get their children protected against polio, just like the parents in Pittsburgh who had jumped through various hoops to get their children enrolled in the clinical study. They knew that this could help advance preventive healthcare, and maybe get their children immunized earlier than would otherwise be possible.

But the research was funded largely by the March of Dimes, which had done a spectacular job of raising awareness of the disease and raising the money, much of it from private citizens donating their own money —many of them sending a dime in the mail, which is how the organization had earned its name. But the March of Dimes became very concerned about the safety of the vaccine, worried that the program could fail in the event that the vaccine turned out not to work well, or to cause harm. Some of what came out in the resulting public discussion sounded similar to what you may now be hearing from from vaccine hesitant people and vaccine opponents in connection with the COVID-19 vaccines. The March of Dimes took the position that the 700 person trial in Pittsburgh was not large enough to prove that the vaccine was safe. And so, there were demands to wait until a much larger study could be completed.

The problem that Salk had with the prospect of a much larger trial was that clinical trials, like the trial that he had completed in Pittsburgh had to divide volunteers into what researchers call study arms. One study arm encompassed children receiving the actual vaccine, but another study arm was a control group. Subjects in the control group had to receive, not the real vaccine but a placebo, basically saline solution, water with salt. Knowing this, based on his data and the fact that the nation was in the midst of a polio epidemic, Salk knew that the placebo group would be in danger, danger from the poliovirus that was spreading about. Consequently, he wanted to start distributing the vaccine nationwide immediately, but if there was to be a large trial, he wanted it to be a field study in which everybody would receive the vaccine, rather than having some children receive the placebo.

Salk did not get his way. A large vaccine trial was organized involving more than 600,000 children, of whom approximately 200,000 were placed in a placebo group, to determine what Salk believed that he already knew from the smaller study: the safety of the vaccine and its potency in preventing polio. The large study did indeed prove the Salk vaccine to be both safe and potent. During the study, however, 16 children died and 34 became paralyzed. These children all were in the placebo group. They died or were paralyzed because they were exposed to the virus without receiving the vaccine, and the numbers were roughly what Salk had predicted based on the statistics run on the data of the smaller study. So you see, in vaccine research, safety is of the utmost importance, but the research works as a double edged sword. Being too careful can have negative consequences in certain situations, like when you are up against a contagious, devastating disease.

David Warmflash
Dr. David Warmflash is a science communicator and physician with a research background in astrobiology and space medicine. He has completed research fellowships at NASA Johnson Space Center, the University of Pennsylvania, and Brandeis University. Since 2002, he has been collaborating with The Planetary Society on experiments helping us to understand the effects of deep space radiation on life forms, and since 2011 has worked nearly full time in medical writing and science journalism. His focus area includes the emergence of new biotechnologies and their impact on biomedicine, public health, and society.

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