The problem with vaccines…

- Boo Chanco - The Philippine Star

The thing with vaccines is that most people do not understand how they work. Vaccines have helped wipe out a good number of childhood diseases and that is why they are widely used worldwide.

But not all vaccines are created equal. Some vaccines only give partial immunity. There are some diseases, influenza for instance, that are caused by a variety of viruses. A flu vaccine made from one type of flu virus may not work on flu infections caused by another.

Modern medicine has also found it difficult to develop vaccines for some viral diseases like dengue. The problem, scientists say, is the difficulty of designing a vaccine that can develop protective immunity, but not trigger a (dangerous) immune response.

What makes dengue so difficult, scientists say, is the backward way it behaves. With most diseases, once people are infected, they are protected. That’s the case with chickenpox and even individual strains of influenza. Dengue is different.

“One of the unique characteristics of dengue is that you seem to be more at risk with your second infection than with your first infection,” according to Dr. Anna Durbin, a professor at the Johns Hopkins University Bloomberg School of Public Health, who is working on the National Institute of Health’s dengue vaccine project.

“There are four types of dengue circulating. Antibodies developed against one subtype protect against only that subtype. But not only do they not help against other strains, they hurt, by enabling the virus to infect more cells and reproduce more quickly and abundantly. We need to make a vaccine that is protective against all four types of dengue, and that’s a very high hurdle.”

Other than the NIH vaccine, GlaxoSmithKline and Sanofi Pasteur have developed live, weakened dengue vaccines that have made it to clinical trials.

Clinical trials are terribly important in the development of new drugs and vaccines. I have heard my father, a professor of tropical medicine and infectious diseases, explain that during dinner conversations at home.

My dad has done a number of clinical trials himself and he has always said there is absolutely no short cut just to meet commercial demand. That’s criminal because one never knows how the human body will react to the new drug or vaccine over time.

What happened with Sanofi’s dengvaxia is precisely what my dad used to warn about. They rushed to market when more extensive clinical trials were called for. Dr Ng Su Peing, global medical head of Sanofi, is now telling us after over 700,000 Filipino children were vaccinated that the vaccine is not recommended for those without prior infection.

If that is the case, DOH should have first tested children if they had prior dengue infection prior to inoculation. Sanofi should have warned DOH.

What’s worse, scientists working on a dengue vaccine had known all along that there is this danger that while the vaccine could lower the number of cases of dengue initially, it could later increase the severity of the disease for those who get it.

My brother in law, a nationally known pediatrician who once headed Lungsod ng Kabataan, tipped me early about the danger of doing mass immunizations of the Sanofi vaccine. He was worried about the phenomenon of ADE (antibody dependent enhancement). We exchanged e-mails on the topic which I wrote about in this column.

“I never recommended this vaccine when it was first introduced,” my brother in law wrote, “because of its low efficacy rate of less than 60 percent in the study that was conducted among Asian countries. What added to my concern was the phenomenon of the vaccine causing severe infection in persons without previous infection known as ADE or antibody dependent enhancement.

“Response to the vaccine is quite complex and may result in more unintended complications. The dengue vaccine can cause most severe illness in children/adolescents without prior history of infection…”

Dr. Antonio Dans, professor of the University of the Philippines College of Medicine, explained it takes time to study ADE. Citing Sanofi’s own studies, Dans explained that ADE may be happening by the third year after vaccination. While the Sanofi and the DOH claimed ADE was only seen in children lower than nine years old, the data showed it could be happening in both younger and older children, and in adults as well.

“The real dengue we are afraid of is severe dengue, not the mild ones,” said Dr Dans. “If a vaccine prevents mild disease but causes severe dengue, we shouldn’t be using it at all.”

Dans pointed out that Sanofi and DOH are aware of the possibility there may be a rise in cases of severe dengue two years after the program is implemented. But they proceeded anyway with mass inoculation instead of doing more clinical trials first.

This to me is sheer recklessness and lack of regard for consequences to human lives by the Aquino administration. This is more criminal than Mamasapano. The consent form DOH made parents sign did not even mention the ADE danger. Parents did not give informed consent.

Maybe, the panic over the rise of dengue cases made the Aquino DOH take the risk. But the large amount of money involved, over P3 billion, can make people think there were other considerations. Clearly, the DOH disregarded good practice.

Sanofi shouldn’t have agreed to sell the vaccine no matter how insistent DOH may have been. That sale is unethical on the part of Sanofi. A class action suit must be pursued against Sanofi if it does not voluntarily agree to refund DOH and also carry the financial burden of treating potential victims.

That photo release showing P-Now watching then Health Secretary Garin inoculate the first child with dengvaxia clearly makes him responsible. P-Noy should have been given the first vaccine shot instead so he can now credibly claim good faith.

Boo Chanco’s e-mail address is [email protected]. Follow him on Twitter @boochanco

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