Why won’t scientists do placebo trials?

In an interview with an Italian journalist, former TV producer Del Bigtree says that vaccines have never been tested in “randomized placebo-controlled” trials. He says it is wrong not to do those kinds of tests.

A placebo is something used in a study to help scientists compare results. Many people think a placebo must always be saline, but that is not true.

There are two common types of comparison groups in vaccine studies. One type is an inert placebo, such as saline. This has no active ingredients. Another type is an active control. This may be another vaccine or vaccine ingredients that are already known to be safe. Active controls help scientists compare a new vaccine to something already understood.

Scientists choose the type of comparison based on the study. A saline placebo can be used when there is no vaccine that already works. But if a safe and effective vaccine already exists, it may be unethical or wrong to give some people only saline. That would leave them unprotected from a serious disease.

Giving protection is especially important for babies and children. If scientists already know a vaccine can prevent serious illness, they do not want to leave some children unprotected just to use saline in a study.

The pneumococcal vaccine is a good example. Prevnar-13 was tested against Prevnar-7, an older vaccine that already worked. If researchers had used saline instead, some children would have been left unprotected from dangerous bacterial infections. That could have put them at risk of serious illness or death. In cases like this, scientists compare a new vaccine to an older trusted vaccine. This helps them see if the new vaccine works as well or better, while still helping protect the people in the study.

Both saline placebos and active controls are accepted in science. These studies look at two main questions: Is the vaccine safe? And does it protect people from disease?

Some people claim childhood vaccines were not tested with saline placebos. That is not accurate. Many vaccines have been tested with saline placebos, including vaccines for rubella, pneumococcal disease, Hib disease, HPV, polio, measles, Tdap, and COVID.

After vaccines are approved, safety checks do not stop. Researchers keep studying vaccine safety over time and monitor millions of real-world doses.