Tag: pertussis vaccines

Do More Vaccinated or Unvaccinated Kids Get Pertussis?

While this seems like a simple question, the answer is a bit more complicated than most people imagine.

Do More Vaccinated or Unvaccinated Kids Get Pertussis?

For anti-vaccine folks, the answer is clear – more vaccinated kids get pertussis. They put all of the blame for pertussis outbreaks on waning immunity. Of course, that’s not the whole story.

While 10% of kids got pertussis, unless you are at a Waldorf school, it is unusual to find that many completely unvaccinated children.
While 10% of kids got pertussis, unless you are at a Waldorf school, it is unusual to find that many completely unvaccinated children. Plus, we don’t know the vaccine history of 40% of these kids.

While it might technically be true that more vaccinated kids get pertussis in the average outbreak, that’s only because there are many more vaccinated kids!

A more accurate and useful answer, taking into account attack rates, makes it clear that a higher percentage of unvaccinated kids get pertussis in these outbreaks.

“In conclusion we have described a school-based outbreak of pertussis that may have been fueled by moderate vaccine effectiveness combined with a failure to vaccinate.”

Terrenella et al on Vaccine effectiveness of tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccine during a pertussis outbreak in Maine

In a pertussis outbreak in Maine, attack rates were much higher in unvaccinated kids, even though more vaccinated kids got pertussis. While 29 of 214 vaccinated kids got pertussis, a much higher percentage of unvaccinated kids got sick – 6 of 28.

That means your risk of getting pertussis was much higher if you were unvaccinated.

A 2013 pertussis outbreak in Florida is a good example that even with all the bad press it gets, the DTaP and Tdap vaccines work too. This outbreak was started by an unvaccinated child at a charter school with high rates of unvaccinated kids. About 30% of unvaccinated kids got sick, while there was only one case “in a person who reported having received any vaccination against pertussis.”

In another 2013 pertussis outbreak in Florida, this time in a preschool, although most of the kids were vaccinated, the outbreak started with “a 1-year-old vaccine-exempt preschool student.” And the classroom with the highest attack rate, was “one in which a teacher with a laboratory-confirmed case of pertussis who had not received a Tdap booster vaccination, worked throughout her illness.”

Why do so many unvaccinated kids get pertussis these days?

“We found evidence of an increase in exemption rates, spatial clustering of nonmedical exemptions, and space-time clustering of pertussis in Michigan. There was considerable overlap between the clusters of exemptions and the clusters of pertussis cases.”

Omer et al on Geographic Clustering of Nonmedical Exemptions to School Immunization Requirements and Associations With Geographic Clustering of Pertussis

Besides the fact that they are unvaccinated and unprotected?

“Children of parents who refuse pertussis immunizations are at high risk for pertussis infection relative to vaccinated children. Herd immunity does not seem to completely protect unvaccinated children from pertussis.”

Glanz et al on Parental refusal of pertussis vaccination is associated with an increased risk of pertussis infection in children.

They can’t get away with hiding in the herd.

Another important consideration – in addition to the fact that more unvaccinated kids get pertussis, when they get pertussis, it is more severe than those who are vaccinated.

“Serious pertussis symptoms and complications are less common among age-appropriate number of pertussis vaccines (AAV) pertussis patients, demonstrating that the positive impact of pertussis vaccination extends beyond decreasing risk of disease.”

McNamara et al on Reduced Severity of Pertussis in Persons With Age-Appropriate Pertussis Vaccination-United States, 2010-2012.

Still thinking of skipping or delaying your child’s pertussis vaccine?

More on Do More Vaccinated or Unvaccinated Kids Get Pertussis?

What to Do If Your Child Is Exposed to Pertussis

Although things are much better than they were in the pre-vaccine era, we still have pertussis outbreaks in the United States.

How does that work?

Waning immunity and folks who are unvaccinated.

How Contagious is Pertussis?

Pertussis is very contagious, but not quite as contagious as other vaccine-preventable diseases, such as measles.

That’s why the focus on controlling pertussis outbreaks is usually looking at close contacts – those who were within about 3 feet for at least 10 hours a week or who had direct face-to-face contact with the person when they were contagious.

Have you gotten a letter from your child's school about pertussis yet?
Have you gotten a letter from your child’s school about pertussis yet?

So when you get a letter about a possible case of pertussis in your child’s school, it may be a a general warning and not that your child is at risk.

How do you get pertussis?

“Persons with pertussis are infectious from the beginning of the catarrhal stage through the third week after the onset of paroxysms or until 5 days after the start of effective antimicrobial treatment.”

Manual for the Surveillance of Vaccine-Preventable Diseases

Spread by respiratory droplets (coughing and sneezing), pertussis symptoms usually start about 5 to 10 days after being exposed to someone else who is in the early stage of their pertussis infection.

While pertussis symptoms can linger for up to 10 weeks, someone who has pertussis is most contagious during the first 2 or 3 weeks of symptoms.

Is Your Child Protected Against Pertussis?

Two pertussis vaccines, DTaP and Tdap, help protect us against pertussis.

In the Unites States, they are routinely given as a primary series (DTaP) at 2, 4, and 6, and 15 to 18 months, with a booster dose at age 4 years. And then a booster of Tdap at age 11 to 12 years. Later, Tdap is given again during each pregnancy, between 27 and 36 weeks gestation. Adults who have never had a dose of Tdap should get caught up, especially if they will be around a baby.

Protection from the pertussis vaccines wanes or wears off, so even fully vaccinated children and adults can still get pertussis. Of course, you are much more likely to get pertussis if you are unvaccinated and you will likely have more severe illness if you are unvaccinated.

Postexposure Antimicrobial Prophylaxis for Pertussis

Fortunately, as with meningitis was caused by Neisseria meningitidis and Haemophilus influenzae type b (Hib), taking antibiotics after being exposed to someone with pertussis can help prevent you from getting sick.

There are only specific situations for which this type of postexposure antimicrobial prophylaxis is recommended though, so for example, you wouldn’t usually give everyone in a school antibiotics because a few kids had pertussis.

Why not give antibiotics to everyone who might have been exposed to someone with pertussis?

“…there are no data to indicate that widespread use of PEP among contacts effectively controls or limits the scope of pertussis outbreaks.”

Postexposure Antimicrobial Prophylaxis

In addition to the fact that it likely wouldn’t stop our pertussis outbreaks, overuse of antibiotics can have consequences.

Situations in which postexposure antibiotics (azithromycin, clarithromycin, and erythromycin, or Bactrim) likely would be a good idea include:

  • household contacts of a known pertussis case
  • to help control an outbreak in a limited closed setting, like a daycare
  • contacts of a pertussis cases who are at high risk for severe pertussis, including pregnant women, infants, especially infants less than 4 months old, and people with chronic medical problems
  • contacts of a pertussis cases who are also contacts of someone who is at high risk for severe pertussis

What if you were exposed to someone with pertussis and have already gotten sick?

If your child was exposed to pertussis and is now coughing, then in addition to antibiotics, pertussis PCR testing and/or culture will also likely be done to confirm that they have pertussis. And remember that their contacts might need postexposure antibiotics.

Kids who have been exposed to pertussis and who have been coughing for more than 3 weeks won’t need antibiotics or testing, as it is too late for the antibiotics to be helpful and likely too late for testing to be accurate. Fortunately, after 3 weeks, they should no longer be contagious.

What to Do If Your Unvaccinated Child Is Exposed to Pertussis

Unvaccinated kids who are exposed to pertussis should follow the postexposure antimicrobial prophylaxis guidelines.

They should also get caught up on their immunizations, including DTaP if they are between 2 months and 6 years, or Tdap if they are older.

What to Do If Your Vaccinated Child Is Exposed to Pertussis

Since protection from the pertussis vaccines wanes, even kids who are fully vaccinated should follow the postexposure antimicrobial prophylaxis guidelines if they are exposed to pertussis.

Then why get vaccinated?

Again, being vaccinated, your child will be much less likely to get pertussis than someone who is unvaccinated. Even though the pertussis vaccine isn’t perfect, it has been shown that children who had never received any doses of DTaP (unvaccinated children) faced odds of having pertussis at least eight times higher than children who received all five doses.

What to Know About Getting Exposed to Pertussis

Talk to your pediatrician if your child gets exposed to pertussis to make sure he doesn’t need post-exposure prophylaxis to keep him from getting sick, even if you think he is up-to-date on his vaccines.

More on Getting Exposed to Pertussis

Do Pertussis Vaccines Work Against Pertactin-Negative Pertussis Bacteria?

Whooping cough is back!
This is not the first time that whooping cough has come back. We also saw a rise when folks got scared to use the DTP vaccine in the 1970s and 80s.

Pertussis vaccines aren’t perfect.

Few people claim that.

But what’s the problem with them?

Most experts think that the main issue is waning immunity.

While the acellular pertussis vaccines (DTaP and Tdap) that replaced the more effective whole cell pertussis vaccine (DTP) do work, the immunity they provide does not last as long as we would like.

They still work better than not getting vaccinated at all though.

Pertactin-Negative Pertussis Bacteria

What about the fact that we are starting to find pertactin-negative pertussis bacteria?

Does that mean that Bordetella pertussis, the bacteria that cause pertussis or whooping cough, have mutated and are causing a pertussis resurgence because they are resistant to the vaccine?

“CDC is currently conducting studies in the United States to determine whether pertactin deficiency is one of the factors contributing to the increase in the number of reported pertussis cases. CDC will continue to closely monitor the situation and evaluate all available scientific evidence before drawing any conclusions. There is also no suggestion that these new strains are causing more severe cases of pertussis.”

CDC on Pertactin-Negative Pertussis Strains

While an interesting theory that the anti-vaccine movement has latched on to, the answer seems to be no.

While pertactin-negative pertussis are certainly a thing, there is already evidence saying that they are not driving pertussis outbreaks – evidence that anti-vaccine folks like to ignore:

  • pertactin is only one of the components (antigens) of the pertussis bacteria that are in pertussis vaccines that help them to induce immunity. Others can include filamentous hemagglutinin, chemically or genetically detoxified pertussis toxin, and fimbrial-2 and fimbrial-3 antigens.
  • pertussis vaccines continue to be effective against pertactin-negative Bordetella pertussis bacteria
  • pertactin-negative Bordetella pertussis bacteria have not been found in all areas experiencing outbreaks of pertussis, as you would expect if they were driving these outbreaks
  • the first pertactin-negative Bordetella pertussis bacteria were found as early as the 1990s, long before we started using the current acellular versions of pertussis vaccines and before we started seeing an increase in outbreaks.

Also of note, pertactin-negative Bordetella pertussis bacteria do not cause more severe symptoms than pertactin-positive bacteria.

“Although pertussis vaccines aren’t perfect, vaccination remains our best prevention tool and we should continue to maintain high levels of DTaP coverage among children, sustain Tdap coverage in adolescents and increase Tdap coverage in adults and pregnant women. ”

CDC on Coughing up the Facts on Pertussis

Most importantly, it should be clear that pertussis vaccines work as we are not seeing pre-vaccine era levels of pertussis, even as we do see some outbreaks.

What To Know About Pertactin-Negative Pertussis

Pertactin-negative pertussis bacteria are not driving outbreaks of pertussis or whooping cough, and they have not become resistant to pertussis vaccines.

More About Pertactin-Negative Pertussis Bacteria