I will make this introduction brief. Many have inquired on my take on Dengvaxia. I will dot the “i”s and cross the “t”s. I will not delve in politics but on science. After all, we all know where politics has led us. Hopefully, this article will educate everyone, using layman’s terms on the good and bad of Dengvaxia.
Does the vaccine work? (Efficacy)
Like all medicines and drugs (and supplements), there is no 100% guarantee on anything. More so for biologicals that require appropriate cold chain handling from the get go up to the time before it is administered to the patient! Because of the many unknowns in between, an investigational drug in clinical trial settings are sadly, handled much better, than when it is already in the market.
There is no perfect vaccine (or medicine to treat an illness). But to answer the question, yes it works to a certain extent. Efficacy endpoints vary from patient to patient. Their immune status, genetic markers, allergy history, age, risk factors and overall disease are but a few considerations on why patients respond to or fail to respond to or develop adverse effects to medicines.
How a vaccine is handled should be exhaustively evaluated as well. Some vaccines are easily destroyed when they are left to stand at poor temperature controls. In the private clinics, vaccines are given to patients directly from the refrigerator (or other appropriate cold chain source). Public health programs must assure that this cold chain is addressed properly – from the warehouse to the program site to the time of administration of multi-dose preparations. Vaccines inappropriately stored properly are like blank bullets. It gives you a false sense that you’re protected when in reality you’re not.
The take home message here is that the drug itself cannot be solely the problem if it doesn’t always work the way it’s expected to. It’s like giving license to a bullet and expecting it to do wonders at protecting you from harm. Without the gun and without appropriate knowledge on how to use the gun, the bullet can either be useless or deadly.
Is it safe? (Safety)
Like all medicines fresh out of clinical trials, there is much information that still needs to be gathered. Yet.
With all the essential clinical trial phases already concluded, relevant findings on the safety (and efficacy) of a medicine at the time it is released for commercial purposes is most likely ready.
Everyone needs to remember that there is NO SUCH THING AS A DRUG WITH NO SIDE EFFECTS. When someone tells you that, the person is lying. No one can assure anyone with absolute certainty that adverse reactions will not occur. However, adverse reactions need to be monitored and managed appropriately.
After all, even medicines which have been in the market for the longest time have side effects. Through the science of pharmacovigilance, we are able to pick up other side effects that once were not seen when these medicines were initially marketed. That’s because when more people are using a medicine, we get to have more information regarding how the drug is to be used and not used. For example, paracetamol is available as an over-the-counter medicine used to treat anything from pain to fever. Making it available as an OTC medicine is based on data continuously being gathered even if it has been in the market for half a century. Yet it is one of the most common cause of drug-induced hepatitis worldwide when used improperly.
Approval from regulatory agencies, anywhere in the world, are based on documentary evidence submitted at the time of application. For example, cancer medicines are approved based on a limited number of patients because the overall population afflicted with the disease may actually be small from the onset. Regulatory authorities may, in certain instances allow drugs for special diseases or compassionate purposes, to submit parts of the application while they are completing the whole clinical trial. In regulatory science, this is called a “rolling submission”.
The appropriateness of this type of submission practice is dependent on how stringent the review is in each regulatory agency for every country.
As the drugs roll out of the pharmaceutical market, there needs to be continuous monitoring of the claims, indications, special precautions, contraindications, drug interactions and adverse events. Only then can we know which medicine is good for both the goose and the gander. As I mentioned, the more patients using a particular medicine, the higher the probability we will find out more about what a drug can, or cannot do.
Is Dengvaxia useful during an outbreak?
The fact that the certificate of product registration of this vaccine has been revoked, will take it awhile to make it available again in the local market. Let’s make it clear. There is NO BAN. The FDA cannot “ban” products at their whim. What revocation means is that the applicant will need to start the whole application process from square one.
But more than the so-called “ban” as a reason for its usefulness (or not) during an ongoing outbreak is the immunization schedule for Dengvaxia. Based on the manufacturer’s data, it is given 6 months apart for 3 doses – 0-6-12 months – in order to achieve the optimum immune response for the vaccine.
Finally, the approved age for vaccine use is 9 years and up. Even on the presumption that, say, more than 80% of Filipinos in certain areas of the country may have had one episode of dengue by the time they are 9 years old, majority of the patients with severe dengue are children 4-7 years old. Which makes this vaccine useless for the people who need it most.
The final say
Unfortunately, nothing in this world is risk free. In the world of medicine, the astute physician weighs benefits over risks when deciding what is best for the patient. Patients must be made to fully understand that thin line of risk over benefit. And consent to agreeing with their healthcare provider on how to prevent, cure or provide comfort against any illness. After all, it is our Hippocratic oath – to first do no harm – that makes us decide, in our best judgement, to err on the side of the best interest of the sick.