Bad science in the Dengvaxia controversy

The ongoing Senate hearing on Dengvaxia may be described—outside clear political undertones in its initiation—as offering a potential breakthrough in the way the public health sector is being organized in the country.

I am referring to the redefinition of the Bureau of Food and Drugs (Bfad) from an attached agency in the Department of Health to an independent bastion of scientific oversight in the country, as suggested by Antonio Dans of the Philippine General Hospital. Such independence is required to balance the policymaking power of the Department of Health, which, in the case of Dengvaxia, had leaned toward the financial and away from sound science. Moreover, the new Bfad will have the adequate budget to perform the seroepidemiological studies that dengue expert Scott Halstead had recommended.

There were already signs of uncertainty in the efficacy of Dengvaxia before its distribution. First, the Formulary Executive Council did not recommend a mass vaccination of Dengvaxia. Second, Halstead already raised caution on vaccinating children without clear exposure to any serotype of the dengue virus. Third, there was no clear data-based long-term protection associated with the vaccination (the clinical trial was only then on its third year).

The endemicity and growing cases of dengue, however, demanded some urgency of action.

The problem with the uncertainty in the science of Dengvaxia was that uncertainty can either be positive or negative. It can be about negative efficacy as Halstead estimated. Please take note that this “negative efficacy” is only a “theoretical risk” because it had not been studied. Conversely, it can also be positive because Dengvaxia may still be able to deliver the promises made about it.

The missing link in this bad science, from the side of the Philippines, was the lack of at least one seroepidemiological study to ascertain that a target community for mass vaccination had really been exposed to the dengue virus. This mistake exposes the reality that the Philippines is far from being evidence-based in its public health practice. If blaming is the game, everyone, from educators to policymakers, can be blamed for that.

What policymakers can do to improve our public health situation is to demand that decisions made must be evidence-based, and not resting on some mental inferences based on uncertain grounds.