Pertussis is making a comeback – what’s the best protection?

The Pediatric Insider

© 2019 Roy Benaroch, MD

Pertussis is also known as “whooping cough”, or sometimes “the 100 day cough”, or sometimes “DAMMIT WHY CAN’T I STOP COUGHING?!”. It is truly miserable. In adults and teens, three months of coughing – and I mean serious, loud, hard coughing, sometimes until you break a rib, vomit, or pass out – is not fun. Young babies, instead of coughing their little heads off, sometimes just stop breathing.

Unfortunately, it’s making a comeback. Both national statistics and our experience at my offices are showing increasing numbers of pertussis cases. Pertussis had become very uncommon with widespread vaccination by the 1980s. Why is it back?

(Aside: about 25 years ago, in my very first month of training as a pediatrician, I was taking care of a newborn in the emergency department who stopped breathing. Completely. Just stopped. Turned blue and floppy. I was terrified, but kept my cool and performed mouth-to-mouth resuscitation. The baby did fine. Later, my attending told me to never use my mouth on a baby – there was resuscitation equipment literally hanging on the wall behind me that I didn’t think to use. Oops. Later, I found out the baby had pertussis.)

The first pertussis vaccine was developed in the 1930s, and in the 1940s it was combined with tetanus and diphtheria vaccines to create the “DTP” vaccine. This was very effective at preventing pertussis, but it was quite “reactogenic”. DTP commonly causing fevers and sometimes febrile seizures (which, by themselves, are harmless – but really scary.) There were cases of encephalitis and dramatic developmental regression seen, too, though it’s become clear since then that these were cases of the genetic condition Dravet Syndrome, which unfortunately starts showing symptoms around the time DTP was given. The quest was on for a pertussis vaccine that caused fewer fevers, and a newer, more purified “acellular” DTaP was developed.

After extensive studies showed that the DTaP was effective and caused fewer fevers, the acellular vaccine replaced the older, “whole cell” vaccine in the US and many other developed countries in the 1990s. And, at least at first, things seemed to go well. Pertussis cases remained low.

But we’ve seen a steady increase in cases over the last 10-15 years. Part of that could be ascertainment bias – there are newer, better, and faster tests for pertussis that have come into wider use, and doctors think about testing more kids for pertussis now that’s clear there are more cases. That doesn’t explain all of the increase.

A study published this week in Pediatrics has helped clarify what’s going on. About a half million children managed at the huge Kaiser Permanente system in Northern California were studied, looking at their pertussis vaccine status and the rates of proven cases of pertussis in the group. Almost 750 cases of pertussis were documented in these children from 2006-2017, revealing some important conclusions:

• Pertussis risk, overall, was 13 times higher in unvaccinated versus fully-vaccinated children. The vaccine is protective.
• Still, 80% of the cases occurred in children who had received the full set of doses. Pertussis immunity dropped off over time – and the longer since the most-recent dose, the more at-risk a vaccinated child became.

So what should we do?

First: widespread, continued universal DTaP vaccinations in infancy and Tdap boosters for preadolescents is still a good idea. It is far better than not vaccinating. The Kaiser data clearly shows vaccinated individuals are at lower risk. Since one of the highest risk groups for severe disease is newborns, vaccinating pregnant women is a key strategy. Though maternal pertussis immunity after Tdap doesn’t last long, it does last long enough to transfer protective antibody to the unborn baby, providing crucial protection during the first few months of life.

But we clearly need a better vaccine and other strategies to provide better, more-lasting protection. Alternatives are being studied, including a nasal-spray pertussis booster and new, adjuvanted vaccines that can hopefully provide more-lasting protection safely. New vaccines take many years to study, so don’t expect anything on the market soon.

In the meantime, we need to do the best we can. Make sure you and your children are fully vaccinated against pertussis, and follow the recommendations for all vaccines. We need to be a better job developing better tools, but in the meantime we could be doing a better job using the tools we’ve already got.

Great news about pertussis protection for newborns: Vaccinate mom!

The Pediatric Insider

© 2017 Roy Benaroch, MD

Pertussis (AKA “whooping cough”) is a nasty bear of an illness in older children and adults. People with pertussis cough for about 100 days – and it’s a horrible cough that sometimes makes people puke, pass out, or wet their pants. Seriously. Three months of that.

But it’s even worse for little babies, especially newborns, who just don’t have the lung power to expel the mucus. They cough, sure, but a lot of them get encephalitis and seizures, and some of them just stop breathing. So it’s especially important to protect the youngest babies.

Rates of pertussis have been climbing, in part because the newer vaccine that we started using in the 1990s doesn’t seem to give as lasting immunity as the old-school, whole-cell vaccine of earlier days. And as more pertussis circulates in communities, it’s the little babies who suffer the most. Pertussis vaccines are given to babies at 2, 4, and 6 months – and that means they build own protection slowly over the first year. Fortunately, a study published today shows that we can prevent most cases of newborn pertussis – even in babies too young to have gotten the full benefit of their own vaccines.

Researchers from the Kaiser Group of Northern California looked at records of all of the babies born at their facilities from 2000-2015 (those years spanned two big California pertussis outbreaks, in 2010 and 2014.) They hypothesized that a strategy of vaccinating pregnant women against pertussis, recommended since 2011, would help prevent pertussis in their newborns. Since people enrolled in Kaiser get all of their care at Kaiser locations, they could track which babies caught pertussis and they could tell which moms got a dose of pertussis vaccine during pregnancy.

They had a lot of babies to track – about 150,000. 17 of those babies caught pertussis in the first 2 months of their lives, and 110 caught it within the first year. The authors compared the rates of pertussis among babies whose mom got the Tdap (tetanus-diphtheria-pertussis) vaccine during pregnancy versus those who did not.

Of the 17 newborns less than 2 months with pertussis, only 1 had a mom who was vaccinated during pregnancy – working out to a vaccine effectiveness of about 90%. Looking down the road as the babies got older and received their own doses of pertussis vaccine, the effectiveness of maternal Tdap remained strong throughout the first year. There were no signs that maternal vaccination interfered with the effectiveness of the babies’ vaccines.

This is great news – an easy and effective easy way to prevent a potentially devastating disease of young babies. Previous studies have shown that this vaccine is also very safe for both pregnant women and their babies. Keep your babies safe – make sure, moms, you get a dose of Tdap during every pregnancy.

It’s time to rethink pertussis prevention

The Pediatric Insider

© 2016 Roy Benaroch, MD

A large, sobering study published in the March, 2016 edition of Pediatrics illustrates just how far we still need to go to effectively control pertussis.

Pertussis, also known as ‘whooping cough’, is a serious illness. Older children and adults get to enjoy a horrible cough for about three months—a cough that sometimes makes people vomit, break ribs, or pass out. Seriously. You haven’t seen a “bad cough” until you’ve seen the cough of pertussis. Worse: in little babies pertussis can cause breathing problems, seizures, and death. Though its caused by a bacteria, antibiotics (unless given very early) are ineffective at reducing the length or severity of pertussis. Prevention, in this case, is worth far more than a pound of cure.

Up until the mid-1990s, infants and children routinely received the whole-cell DTP vaccine (DTP = diphtheria, tetanus, pertussis.) It worked at preventing all three of these diseases, but had a relatively high rate of side effects, mostly fevers. Many of the suspected more-serious side effects (like encephalopathy and seizures) are now known to have been caused by genetic conditions, not the vaccine, but nonetheless parents and doctors alike welcomed a newer vaccine, the acellular DTaP. This newer vaccine, which replaced DTP in the United States by around 1998, caused fewer fevers, and was thought to cause fewer serious reactions, too.

The problem is that it just doesn’t work as well. And as the first generation of infants to get an all-DTaP series starts to go through adolescence, we’re starting to see the unintended consequence of that vaccine change.

In the current study, researchers used a huge database of information from the Kaiser Permanente system of Northern California. We’re talking solid, big-data research, here, the kind of study that requires consistent and reliable data across a huge set of patients. In this case, about 3.5 million patients across 55 medical clinics and 20 hospitals, using centralized labs and an integrated medical records system. If health things happen to this population, Kaiser knows it.

In 2010 and again in 2014, California experienced large epidemics of pertussis. A total of 1207 cases were among Kaiser teenagers, all with complete records of their pertussis vaccination status. And the results aren’t anything to be happy about. In the first year after an adolescent pertussis (Tdap) booster, the vaccine was about 70% effective in protecting against pertussis. Not great, but not terrible, either – until you look a few days down the road. The vaccine effectiveness drops off dramatically, year after year, down to only about 9% by four years after receipt of the vaccine.

Why does Tdap seem to provide such poor protection—much worse than was seen in the original licensing studies? It’s a generational change, and it goes back to the shift from DTP to DTaP in the mid-1990s. By now, these teens in California are old enough to have received DTaP, not DTP, as infants. The authors looked at the specific ages of pertussis cases during the 2010 and 2014 outbreaks, and the trends support the conclusion that teens who received DTP as infants get good, lasting protection from Tdap; teens who got DTaP do not.

Now what? Clearly, we need a more-effective vaccine, perhaps even resuming the use of whole-cell pertussis vaccine, at least for the earlier doses. But in the meantime, we have to do the best we can with what we have. Vaccinating pregnant women with Tdap does effectively prevent pertussis in their babies, especially when they’re the youngest and most-vulnerable. And adults (who got DTP as children) should get Tdap boosters too, to protect the children around them. Another idea (floated by the study authors) is to use Tdap in teens not as a routine booster, but as a strategy to control local outbreaks, taking advantage of the higher effectiveness seen for the first year after vaccination.

I don’t have the answers. I’m not happy to see studies like these, but examining and re-examining vaccine safety and effectiveness is something we need to continue doing, with an open mind, relying on solid evidence. Bottom line: with pertussis, we need to do better.

Yet more evidence for the safety and effectiveness of vaccines

The Pediatric Insider

© 2013 Roy Benaroch, MD

Item #1: A study of about a million (!) girls in Sweden and Denmark showed no serious side effects, none at all, after administration of the HPV vaccine.

Item #2: Another study, looking at children vaccinated against influenza from 2010-2012, showed a 77% reduction in life threatening flu illness.

Item #3: From JAMA Pediatrics, a study showing that among children 3-36 months of age, those who hadn’t received their routine vaccines had 18 times the risk of pertussis compared to fully vaccinated children.

What do these studies have in common? They’ve all been published within the last few weeks, and they’re good, solid science. They’ll also be ignored by the hardcore anti-vaccine crowd, for whom no amount of evidence matters one bit. They’ve made up their minds, and they have no interest in what scientists or doctors or anyone else has to say—unless you already agree with them.

Jonathan Swift said, “It is useless to attempt to reason a man out of a thing he was never reasoned into.” People who have come to their antivaccine views out of hysteria and fear have not used reason. And I don’t think there is much hope to convince them of anything.

But the vast majority of vaccine-questioning parents aren’t like that. They want good, reliable information to help them make their decisions. Studies like these continue to be published, hundreds of them a year. As more evidence accumulates, the safety and effectiveness of vaccines continues to be reinforced. We’re learning more and more about the immune system and how to protect ourselves, and newer vaccines have been very effective. That’s great news for those of us who want to do what’s best to protect our children, or families, and our communities.

Vaccines for parents

Jeffery asked, “Dr. Roy, my wife and I are currently trying for a new baby. I know you are a pediatrician but we had a question for you regarding adults and vaccinations. We heard from friends tonight at dinner that vaccinations we received as a child are worn off by the time we receive our 30’s. My wife and I are both in our early 30’s and this concerns us especially since we are trying for another child. Should we be receiving boosters for our immunizations? Also, this concerns us especially since my wife’s family doesn’t believe in vaccinations so all my daughter’s cousins are not vaccinated. Are we safe? Should we get vaccination boosters? Thank you. Also, we love you as our pediatrician!”

There are two vaccines that parents of young children should receive to protect their families.

The first is called Tdap, short for Tetanus-Diphtheria-acellular Pertussis (this also goes by the brand names Adacel or Boostrix). This has essentially replaced the old “tetanus shot.” In addition to protecting against tetanus and diphtheria, Tdap provides protection against pertussis, also called “whooping cough.” Pertussis immunity wanes quite quickly after childhood vaccination or natural pertussis infections. In a child or adult, pertussis causes a severe cough that can persist for months. In a small infant or newborn, pertussis can cause respiratory failure, seizures, or death. Because of waning immunity and a vaccine that’s not 100% effective, pertussis is still common among adults and school children. Parents of small children and babies should receive a Tdap booster, though this shouldn’t ordinarily be given to mom while she’s pregnant. (It may be a good idea even for pregnant women to get a dose of Tdap if there is a local outbreak, but this should be discussed individually.)

Parents looking forward to having a newborn should also receive a dose of influenza vaccine. This can be a very serious infection in a very young baby (or, at the opposite end, in the elderly.) Influenza vaccine can also be given safely to pregnant women, giving protection to the baby from the minute of birth.

I’m sorry to hear that many cousins in your family are not vaccinated. There is a tremendous amount of misinformation and scare-mongering going on, and unfortunately even well-meaning parents can get caught up in the hysteria. I recently reviewed an excellent book about the teetering tower of lies that created the myth of vaccines and autism—maybe that would make a nice gift for that part of the family, and could help improve the health of their children. Best of luck with that.

Don’t split the vaccines

Brook asked a good question: “I am curious to learn more about the timing and combining of multiple vaccines. As a disclaimer, may I please add – I do not fear vaccines, and I certainly think they are helpful and necessary as opposed to harmful to my children. I read that the CDC recommends that the MMR, DTAP, IPV, & Varivax vaccines be administered between the ages of 4 years and 6 years. My pediatric group recommends that all four vaccines be administered at the same visit at the age of 4 years. I wonder why they aren’t spaced such that 2 shots are given at 4 years and 2 shots at 5 years or something similar. Are there advantages to spacing the vaccines? Are there risks in administering multiple vaccines in one visit? Are the shots administered in each of the limbs? Any insight you could offer would be greatly appreciated. I am not sure if I should request that the vaccines be administered over 2 or 3 visits to make sure my child’s immune system isn’t overburdened and he fully benefits from them.”

Giving these vaccines poses no added risk versus giving them all at once, and as a pediatrician who has supervised vaccinations for many years, I’ll tell you that it’s much, much easier on the child to get them all over with at once.