Dengue Vaccine in Philippines: Considerations For Reintroduction
Source: immunizationinfo.com

Dengue Vaccine in Philippines: Considerations For Reintroduction

Also known as ‘breakbone fever’, dengue is a painful disease caused by the dengue virus. The virus is transmitted by the Aedes Aegypti mosquito, which is common to all of Philippines. 

The threat of dengue in Philippines

The Philippine’s health department estimates that up to 64% of dengue cases in this country are of the DEN-3 genotype, which increases the risk of diseases such as pneumonia in secondary dengue infections. 

Thousands of dengue cases and hundreds of deaths related to the dengue virus are reported in the Philippines every year.

Signs and symptoms of dengue fever

According to the Center for Disease Control and Prevention (CDC), about 25% of those who are infected with the dengue virus will get sick. Symptoms can be mild to severe. Severe cases can be life threatening and require hospitalization. Those who have had dengue before have an increased risk of developing severe dengue. 

The most common sign of dengue is fever that is accompanied by:

  • Rash
  • Aches and pains – joint pain, bone pain, muscle pain and eye pain
  • Nausea and vomiting

Warning signs that point to severe dengue usually occur 24 to 48 hours after the fever has subsided. Symptoms include:

  • Vomiting 
  • Vomiting blood
  • Blood in the stool
  • Stomach pains or tenderness
  • Bleeding from the gums and/or nose
  • Feeling tired and restless
  • Feeling irritable

While most people usually recover within a week, severe dengue is an emergency and you should seek immediate medical attention. 

Causes of dengue in Philippines

Dengue outbreaks are not new in the Philippines. According to Rabindra Abeyasinghe, Philippines representative for the WHO, the phenomenon is linked to changing weather patterns. 

Higher temperatures and lengthy rainy seasons are the main reasons for dengue in this nation. The peak period for dengue coincides with the rainy season which occurs yearly from June to February

Philippines dengue outbreak 2019

The 2019 national dengue epidemic saw 16 provinces across the country declaring a state of calamity on the 6th of August 2019. 

The Philippines’ Department of Health reported over 400,000 dengue cases nationwide in 2019. Figures almost doubled from the number of cases reported in the previous year. 

Of the reported cases from January to November 2019, there were 1,502 deaths, compared to the 1,075 deaths in 2018. 

Philippines dengue statistics 2020

As of 31 May, there were a total of 50,169 dengue cases reported. 173 cases resulted in death. While the number of reported cases is 43% lower than 2019 in the same period, the threat of dengue is still evident. 

The public has been asked to be vigilant and take the necessary safety precautions for the rainy seasons when dengue is prevalent as local health authorities pour effort into fighting Covid-19. 

Containing dengue in the Philippines

The fight against dengue is a continuous one in the Philippines. Dengue can be contained by preventing mosquitoes from breeding and/or with an effective vaccine that can fight the virus. 

Practical ways to prevent dengue

Vector control is fundamental in preventing dengue. The cooperation of the whole community is needed to ensure a clean environment that is free of suitable egg-laying habitats. 

The Department of Health of the Republic of the Philippines has asked the public to implement that 4-S strategy in their household to prevent dengue. 

This strategy includes:

  • Search and destroy mosquito breeding grounds – Water storage containers should be covered and cleaned at least once a week, using suitable insecticides in outdoor water storage containers. 
  • Self protection measures – putting on mosquito repellent daily, donning long sleeved shirts and long pants, using window screens, coils and vaporizers.
  • Seek early consultation if you have signs and symptoms of dengue.
  • Support fogging/spraying in hotspot areas where cases have been increasing to stop the occurrence of an outbreak. 

Dengue vaccine

There are 4 types of Dengue vaccines:

  • CYD-TDV – Sold as Dengvaxia, CYD-TDV is a vaccine made from recombinant DNA technology. 
  • DEN-Vax – Also known as TAK-003, DEN-Vax was developed in Bangkok. It is a recombinant chimeric vaccine .
  • TetraVax-DV – This is a tetravalent admixture of monovalent vaccines. The monovalent vaccines were tested separately. 
  • TDEN PIV – Still in phase 1 developmental trails, TDEN PIV is a tetravalent vaccine that is the product of collaboration between GSK and Walter Reed Army Institute of Research. 

Dengvaxia controversy Philippines

Dengvaxia is a dengue vaccine that has been recently approved by the U.S Food and Drug Administration. It is the first dengue fever vaccine. However, Dengvaxia has a dark history in the Philippines that not only ignited panic in the nation but also fueled a measles outbreak that resulted in the deaths of over 355 people. 

Massive dengue campaign

It all started in April 2016 in the capital city of Manila. A massive dengue vaccine campaign was launched with the aim to save thousands of lives as well as to prevent as many as 10,000 dengue related hospitalizations yearly. 

Dengvaxia was developed by Sanofi Pasteur, a French pharmaceutical company. Over 20 years and $2 billion was put into the development of this vaccine. Large trials were carried out with results of the trials published in New England’s Journal of Medicine. 

However, the vaccine did not seem to work for some children. In fact, the disease seemed to be even worse in some children who caught the virus after being vaccinated. This discovery was made by Dr Scott Halstead who spent over 50 years studying the dengue virus.

This occurred especially in children who had never had dengue before they took the vaccine. There seemed to be an increased risk of plasma leakage syndrome in these children. This complication happens rapidly, causing the body to go into shock and often results in death as the patient may not show any outward signs. 

The World Health Organization recommended that Sanofi carry out more research to understand the safety issues at hand, but this was only three months after the vaccination campaign had been launched. 

Following the WHO’s recommendations, Sanofi continued its studies and in November 2017 confirmed Dr Halstead’s suspicions about Dengvaxia. 

There was significant evidence that the vaccine increased the risk of cytoplasmic leakage syndrome and hospitalization in children who had not contracted dengue before. The company wrote that “for individuals who have not previously been infected by dengue virus, vaccination should not be recommended”.

Since the campaign had already vaccinated 800,000 children, the Philippines was hit with panic. There were protests and news outlets reported that the vaccine had contributed to 10 deaths. As it is estimated that 10 to 20% of children in this country have never had dengue, up to 100,000 should not have been given the vaccine. 

Autopsies were performed and up to 600 deaths are still being investigated by the Public Attorney’s Office.  

Problem with Dengvaxia

When a person is given a vaccine, it triggers the creation of antibodies by the immune system. These antibodies then work to fight against the virus when an infection occurs. 

Dengue antibodies, however, do not work this way. The antibodies carry the virus to the whole body and help it to spread. The body produces antibodies against the vaccine which means that Dengxavia is similar to the first infection for those who have not previously come into contact with the dengue virus. 

According to Sanofi, the vaccine increases hospitalization after a dengue infection from 1.1% to 1.6%. While this seems like a small risk, it means that an estimated 1,000 out of 1,000,000 children will be hospitalized because of the vaccine. 

Repercussions

For the Philippines, 14 government officials were indicted for the deaths of the 10 children who were given the vaccine. The Philippine Department of Justice found that the vaccine was administered by untrained health workers and before clinical trials were completed. Children with preexisting medical conditions were also given the vaccine. 

As for Sanofi, 6 officials were charged for not giving aid to children who had severe dengue due to the vaccine. Sanofi disputes this. 

Mistakes with vaccine safety and lack of information will have long term consequences for the nation.  A study found that confidence in vaccines decreased tremendously from 82% in 2015 to 21% in 2018 after the Dengvaxia scare. Parents who believed that vaccines were important went from 93% to 32%.

Because of this, fewer children are vaccinated, causing an increase in childhood diseases. There were more than 26,000 cases of measles that resulted in 355 deaths in 2019. 

Considerations to reintroduce Dengvaxia in Philippines

According to Reuters, the Philippines is weighing to reuse Dengvaxia to help fight dengue. With hundreds of thousands of cases just this year, dengue continues to be a real threat in this nation. 

Presidential spokesman Salvador Panelo said that “It would be used with utmost caution” and that the government would take care to adhere to all protocols that had been set by the WHO when administering this vaccine.  

Conclusion

While the preventive measures to halt the breeding of mosquitoes helps stem the spread of dengue, vaccination against the virus will help keep infection numbers low. 

Vaccination will also reduce dengue related hospitalizations, which numbers in the tens of thousands every year. However, there is a need to assure the people of Philippines that dengue vaccines such as Dengxavia are safe when administered according to the directions set by the WHO. 

With vaccine confidence at an all time low after the Dengxavia controversy, this will no doubt be a big challenge to Philippines health officials. 

 

Leave a Reply