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Dengue, Death and Dengvaxia

SYP, GHME, 2019

Dengue Fever

Growing up in the Philippines, I have always heard about Dengue. There was never a year that the word ‘Dengue’ was not mentioned on televisions, schools, or family gatherings. It has become part of my childhood and is continuously being part of the life of Filipinos. Dengue is scary enough that health practitioners internationally have been eagerly awaiting a vaccine for decades.

The World Health Organisation (WHO) defines Dengue as ‘a mosquito-borne flavivirus found in tropical and sub-tropical regions of the world, mostly in urban and semi-urban settings. Day-biting Aedes mosquitos spread disease. It is the fastest spreading vector-borne viral disease and is now endemic in over 100 countries, resulting in 40% of the world’s population living in an area at risk for dengue.

Just recently, the Philippines declared Dengue as a national emergency as it killed more than 500 people in the span of 7 months. Dengue has claimed the lives of 622 Filipinos, with nearly 150,000 dengue infections reported until July 26, 2019 - up to 5,000 new dengue cases are reported each week and children are the mostly impacted.

Dengvaxia: a cure or a new health challenge?

The WHO listed Dengue as one of the ten threats to Global Health for the year 2019. This might come as no surprise for Filipinos as we had such bittersweet memories with Dengue and ‘Dengvaxia’.

In 2016, the Philippines’ Department of Health launched its anti-dengue inoculation programme and gave Dengvaxia shots to over 830,000 adults and children in the Philippines. Dengvaxia is the world’s first vaccine against Dengue and is currently the only dengue vaccination available on the market, but the WHO recommends that it should only be given to those in high-risk areas who have already been exposed to the virus. It is rarely used in mass immunisation projects.

However, the Philippines has the distinction of being the first country in the world to introduce Dengvaxia in a mass vaccination programme - but it is now paying the price. The Philippines’ health department is now looking at 24 deaths possibly linked to this mass vaccination. It is a sad reality that Filipino children had been made into guinea pigs in the development of a new dengue vaccine, with the scientific and health community’s reputation taking a hit as well.

In December 2017, around a year later after the Dengue mass vaccination, the French manufacturer Sanofi Pasteur issued a statement saying Dengvaxia vaccine may increase the risk of severe dengue in patients who received it without previous exposure to the mosquito-borne disease. Shortly after that, Philippine health authorities altogether banned Dengvaxia, the world’s first Dengue vaccine.

On the other hand, Sanofi Pasteur insisted their vaccine against dengue works on those who are already infected by the virus to boost their immunity, though the company warned in November 2017 the vaccine did not work on those who have not yet contracted the virus (BMJ, 2017).

Sanofi Pasteur was found by the Food and Drug Administration (FDA) to have shown “complete disregard of government rules and regulations” and in February 2018 the Philippine government decided to ban the vaccine.

The 2019 Aftermath

The nationwide panic and widespread mistrust of vaccinations caused by the Dengvaxia scandal in the Philippines led immunisation rates for both dengue and measles to plummet, resulting in an ongoing measles epidemic across the country and now a dengue epidemic. There have already been more than 35,000 recorded cases of measles and almost 500 deaths, a 600 per cent increase on last year (2018). Filipino parents had developed an aversion for all sorts of immunisation for their children.

Source: Medium

Scientific Advances versus Policy Failures

Filipino authorities were apparently so confident about Dengvaxia’s safety that they did not oblige Sanofi Pasteur to submit results from so-called pharmacovigilance trials that would usually test the safety of a new drug or vaccine in local conditions. The induction of a new pharmaceutical product into the national program typically takes three to five years, but the dengue vaccination program began right away, in April 2016.

Meanwhile, at the time of the vaccination launch in the Philippines, the WHO also hadn’t yet approved the vaccine at the time of mass vaccination (though it did several months later).

Mass vaccination also took place without blood testing — and the way dengue works, it’s safer to get the vaccine if you have had the virus at least once and have some immunity in your blood. But according to trial results, this risk was deemed minimal and could be minimized further by using it only in high-burden countries like the Philippines, where most people have had at least one dengue infection.

The vaccination continued despite some interim reports/researches showing that among Asian children two to five years old, those who had received the vaccine were seven times more likely than unvaccinated children to have been hospitalized for serious dengue in the third year after vaccination.

Since Dengvaxia mimics a prior encounter with dengue—which can prime a patient’s body to respond in a dangerous way to a second dengue infection, the vaccine caused deaths. The vaccine program was halted after 830,000 schoolchildren had been vaccinated.

The controversy has not slowed down the rollout of Dengvaxia, which is currently licensed in more than 20 countries. In October 2018 the U.S. Food and Drug Administration announced that it would prioritize review of Sanofi Pasteur’s application to approve Dengvaxia. That means it could be approved in the U.S., for use in dengue-endemic areas such as Puerto Rico, before the Philippines completes its investigation into the deaths of vaccinated children—and before Sanofi Pasteur publishes its final report from the six-year-long clinical trials.

Questions and Uncertainties

Who should be making the difficult decisions: global bodies of experts, national health authorities, fully informed parents and doctors, or some combination of these? And who should be held accountable when things go wrong? Why Dengvaxia became a global health scandal? Because of science, politics, or procedure? All of the above? Would this end up to be another Global Health failure?

I might not have the best answer for all of these questions now, but one thing is for sure, as a public health practitioner, this Global Health scandal taught me a Global Health lesson – we must do a better job of communicating these risks and guide patients through the process. There should be a full disclosure of the risks (and benefits) of vaccination of persons with unknown dengue status.

“We must do a better job of communicating

these risks and guide patients through the process."

What’s next?

With dengue infecting millions of people every year and appearing in places it has never been before, the need for a safe vaccine is still ever more urgent. Armed with the new information from the Dengvaxia incident of Sanofi, dengue vaccine makers and governments should do things differently (and hopefully better).

The following is my call to action for the following institutions and people:

The WHO, as an international governing body for global health, should support and encourage extensive clinical trials for the dengue vaccine. Furthermore, provide logistical guidance especially for those countries whose dengue surveillance system needs further improvement.

Pharmaceutical companies should make sure to collect baseline blood samples from 100 percent of their research participants in an extensive clinical trial (including people who haven’t had dengue before). This in turn would provide a better baseline data especially if things don't go as expected. Yes, fully assessing safety will likely take more time, but it is worth the wait considering that lives of many people are at stake if anything goes wrong.

Governments should be more rigid and careful when it comes to mass vaccination programs especially if it involves a new vaccine or medication. Governments should seek expert advice from national and international institutions like the WHO whenever they will implement something that involves the public's health and safety. Better public health systems and public health governance should be in place.

To YOU who are reading this, the Dengvaxia incident is not an excuse to not get vaccinated from preventable diseases. Clinically tested and internationally approved vaccines can save millions of lives.

As a final note, we should all remember that this incident is not just the problem of WHO, our governments or private companies. Each of us has to do their own part. You, me, us - TOGETHER, we have to work hard for better health for all.

Finally, it is imperative that we hold each other accountable. Accountability when things go wrong, and accountability to make things right again.

Thank you to Jose Maria ‘Lloyd’ S. Nunag for your thoughtful article.

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