Tag: Dengvaxia

Dengvaxia for Dengue Fever

Dengvaxia was recently approved by the FDA after being available in other countries since about 2015.

“Indicated for the prevention of dengue disease caused by dengue virus serotypes 1, 2, 3 and 4. DENGVAXIA is approved for use in individuals 9 through 16 years of age with laboratory-confirmed previous dengue infection and living in endemic areas.”

Wait.

Dengue is endemic throughout the tropics and subtropics, including most of the Caribbean.
Dengue is endemic throughout the tropics and subtropics, including most of the Caribbean.

It’s only for people who have already had a dengue infection before?

Dengvaxia Controversy

Unfortunately, Dengvaxia “performs differently in seropositive versus seronegative individuals.”

“In areas of 70% dengue seroprevalence, over a 5-year follow-up, for every 4 severe cases prevented in seropositive, there would be one excess severe case in seronegative per 1,000 vaccinees; for every 13 hospitalizations prevented in seropositive vaccinees, there would be 1 excess hospitalization in seronegative vaccinees per 1,000 vaccinees.”

WHO on Questions and Answers on Dengue Vaccines

If you have never had dengue before and you are vaccinated, you are at risk for a severe infection if you do get dengue. On the other hand, if you are unvaccinated, you are at even greater risk of getting dengue, a life-threatening infection. Fortunately, the first episode of dengue is usually fairly mild.

The problem occurs if your antibody levels have dropped enough, which can cause you to have a severe case of dengue the second time. The process is called antibody-dependent enhancement and has to do with antibody levels, either natural or vaccine induced. So it can occur whether or not you are vaccinated, although getting Dengvaxia, an attenuated, live vaccine, can act as a primary dengue infection.

“These differing epidemiological features support the conclusion that antibody dependent enhanced (ADE) dengue disease occurred in seronegatives who were sensitized by vaccine. As hospitalizations continue to occur in all age groups Dengvaxia consumers should be warned that sensitized vaccinated seronegatives will experience enhanced dengue disease into the forseeable future.”

Scott Halstead on Dengvaxia sensitizes seronegatives to vaccine enhanced disease regardless of age.

It is something that dengue researcher Scott Halstead warned folks about as soon as he saw the first published study on Dengvaxia.

But why would you need a vaccine if you have already had dengue?

“In humans recovery from infection by one dengue virus provides lifelong immunity against that particular virus serotype. However, this immunity confers only partial and transient protection against subsequent infection by the other three serotypes of the virus. Evidence points to the fact that sequential infection increases the risk of developing severe dengue.”

WHO on Dengue control

There are four serotypes of dengue.

So if you aren’t vaccinated, you are at risk to get dengue multiple times.

Tragically, about 800,000 children in the Philippines were given Dengvaxia in a universal immunization program without checking to see if they had dengue first. And it likely led to some severe cases of dengue and deaths. This led to the vaccine being banned in that country and is thought to be one of the causes behind their current measles outbreak, as their Dengvaxia controversy led to more vaccine hesitancy.

And it will lead to more folks getting dengue. Instead of a ban, they should likely be more picky about who they give the vaccine to, either confirming that recipients have already had dengue (titer test) or only giving the vaccine to older kids.

Dengvaxia for Dengue Fever

Do you need Dengvaxia?

Remember, Dengvaxia is only for those living in endemic areas and in the United States, dengue is only endemic in the U.S. territories of American Samoa, Guam, Puerto Rico, and the U.S. Virgin Islands.

Do you need Dengvaxia if you are simply traveling to one of these areas?

Since Dengvaxia is not approved for those who haven’t had a dengue infection before, you likely wouldn’t get it just for traveling to an endemic area, unless perhaps you routinely travel to an endemic area and have had dengue already. A titer test can confirm a previous dengue infection, but there is no indication to get vaccinated for travel yet.

Also, while in other countries it is available for use between 9 and 45 years, in the United States, Dengvaxia is only approved for children between 9 and 16 years of age.

More on Dengvaxia for Dengue Fever

Vaccines – Year in Review 2018

Another year has passed and although anti-vaccine folks keep talking about those 300 vaccines in pipeline, there were few new developments in the vaccine world in 2018.

Bob Sears got in trouble with the Medical Board of California over vaccine exemptions.
This happened in 2018.

Well, maybe that’s not entirely true.

Vaccines – Year in Review 2018

So what can we say about 2018 when it comes to vaccines?

Well, we did get some new ones!

  • approved by the FDA in late 2017, a new hepatitis B vaccine for adults, Heplisav-B, the formal recommendation for its use from the ACIP came on February 21, 2018
  • although it was both approved by the FDA and formally recommended by the ACIP in late 2017, Shingrix, the new shingles vaccine, became more widely available in 2018 – well kind of – there have been a lot of shortages due to high demand for the vaccine
  • Vaxelis, a hexavalent vaccine that combines DTaP-IPV-Hib-HepB into one shot was FDA approved on December 21, 2018, but likely won’t be available for a few more years
  • FluMist, the nasal spray flu vaccine, returned

And we lost one… Last year was the first full year that Menomune, an older meningococcal vaccine, was no longer available. It was discontinued because of low demand, as we began to use the newer vaccines, Menactra and Menveo instead.

In other immunization news:

  • a 2017 shortage of yellow fever vaccine continued into 2018
  • a shortage of monovalent pediatric hepatitis B vaccine will continue into 2019 (doesn’t affect combination vaccines with hepatitis B)
  • Gardasil 9 received an expanded recommendation – women and men between the ages of 27 and 45 years can now get vaccinated and protected with this HPV vaccine
  • the hepatitis A vaccine got a lower age recommendation – at least in special situations – “HepA vaccine be administered to infants aged 6–11 months traveling outside the United States when protection against HAV is recommended.”
  • the recommendation to use a third dose of MMR to control outbreaks of mumps was formally approved
  • the WHO updated its recommendations for use of the dengue fever vaccine (Dengvaxia) to makes sure that only dengue-seropositive persons are vaccinated, as they found an increased risk of severe dengue in seronegative people who were vaccinated
  • Of the 163 million to 168 million doses of flu vaccine that will be distributed in the United States for the 2018-2019 season, more than 80% will be thimerosal free.
  • China had an issue with substandard DTaP vaccines made by one company in one part of the country
  • India had an issue with contaminated polio vaccines made by one company in one part of the country – bivalent oral polio vaccines (two strains) still contained all three strains of polio vaccine virus
  • Measles cases and deaths spiked globally because of gaps in vaccination coverage

If you didn’t hear about any of those things in the news, you may have heard about the death of two young children in Samoa after they received an MMR vaccine. That tragedy almost certainly was caused by an error in administering/mixing the vaccines, and not because there was anything wrong with the vaccines themselves.

Need help getting educated about vaccines? Despite continued outbreaks, 2018 was a good year for vaccine advocates and vaccine education.

Several good books about vaccines were published, including:

And in case you missed it, we found out that:

Of course, for most of us, none of this is really news. We know that vaccines are safe, effective, and necessary.

And sadly, Betty Bumpers died. We can honor her legacy by continuing her work and helping to make sure that every child gets vaccinated and protected.

More on Vaccines Year in Review 2018