Pertussis in 2025: A Conversation with Prof. Gordon Dougan

“There is an upward trend in the number of cases of pertussis,” confirms Gordon Dougan, Professor in the Department of Medicine at the University of Cambridge and former head of pathogen research at the Wellcome Sanger Institute in the United Kingdom. According to the Centers for Disease Control and Prevention, there were six times as many cases in the U.S. alone in 2024 than in 2023.

Renowned for his work on enteric diseases, developing the acellular whooping cough (aka pertussis) vaccine in the 1980s, and his lifelong vaccinology work, Prof. Dougan was awarded the Albert B. Sabin Gold Medal in 2020. Here, he talks about the global increase of pertussis and the need to increase immunization and improve diagnostics for this vaccine-preventable disease.

Why is pertussis so dangerous, particularly for babies?

Pertussis is a bacterial infection of the lungs. The organism sits on the surface of the lung where it releases some very nasty toxins. These toxins can not only disrupt lung function, but they can make the baby generally feel very unwell and develop a fever.

But the most alarming symptom is this persistent long-whooping cough. It’s very characteristic if you’ve heard it; parents always recognize it. It’s very distressing to hear your child gulping for air and not quite getting there for a long period of time. The child gets distressed. It can go on for weeks as well. It’s not an acute disease in the sense that it lasts just a few days. It can last for weeks, and both parents and baby can become very distressed.

Has the bacteria changed at all or is pertussis becoming resistant to antibiotics, as is happening today with some other diseases?

Whooping cough/pertussis has been around for centuries. It jumped into the human population, we think, from animals. But in recent years, we’ve noticed some differences. There are two main developments: One is that the bacteria, Bordetella pertussis, appears to be trying to escape vaccination. That’s good evidence that the vaccine is working, but some of the antigens that the vaccine targets are changing, maybe under selection.

The second development is that there are now hints of antibiotic resistance, especially for those antibiotics we use to treat the disease. And there’s two effects of that. One is that you can go on using more antibiotics and still not clear the organism. The other is that you’re also likely to increase the level of antibiotic resistance in other organisms that are beneficial for the child and actually help the child’s lungs function and also prevent other infections.

Pertussis vaccination is often contained within combined vaccines, such as a combined diphtheria, tetanus, pertussis (DTP) vaccine or the newer hexavalent vaccines. Does this make it harder for individuals to keep track?

There are many infections that affect young babies, and we’ve developed a set of vaccines including whooping cough, diphtheria, tetanus, and several others that we tend to give as a single dose. Therefore, parents will not always know that their child has been vaccinated against whooping cough. That is an issue, but we do that really to reduce the number of vaccinations the child actually has to have in the first few months of life. Now we have up to six different diseases we can tackle in one shot, one of which is whooping cough/pertussis.

Are you still working on pertussis?

I’m not working directly on the disease, although I do see cases of the disease fairly regularly. But I do follow the field with great interest. I was involved in the development of the acellular whooping cough vaccine in the 1980s. We worked on one antigen called pertactin, which ironically is one of the antigens that is trying to escape vaccination. So, in my lifetime, I’ve seen this very robust antigen being challenged by the bacteria. There is this constant evolutionary chase between the microbe and the human, trying to live together. We’re trying to prevent the infection. They’re trying to live on us.

Is there a development on the horizon that makes you hopeful about increasing protection?

Well, I think it’s very good that we’re having this conversation because it’s clear that as you see a rise in the disease pertussis, the public becomes aware of it. Awareness is important because it’s such a nasty disease. I’m always optimistic as the vaccine is there to be used. And even if the organism starts to try to escape the vaccine, we will find ways of preventing that in the future. And I’m optimistic that we will continue to improve the way we manage these diseases in children, not only in the richer economies of the world, but also in the poorer economies of the world, where these diseases often go undiagnosed.

When you say better ways to manage, do you mean clinical management?

Better ways to manage would include getting better diagnostics. The organism, Bordetella pertussis, is very tricky to grow in the laboratory. It can be done, but very few laboratories do it. What we really need is very quick, accurate molecular tests — rather like the PCR tests we used in COVID — that we can quickly bring to bear to identify infected children. Then we can put them under better clinical management, whether that’s through antibiotics, and also prevent the disease from passing on to other babies. Interestingly, this disease also affects adults. Adults develop a chronic persistent cough that they often do not know is pertussis. We could get better at diagnosing that because adults will often spread the disease on to other children, which is very unfortunate and unintended.

So you can have an infection and not realize it?

Yes. Often if you’ve got a persistent cough, you should think about that as an option, because it’s quite common. I’ve actually seen that quite a lot.

When should someone check if a cough could be pertussis?

Pertussis in children is quite an easy disease to recognize. You get this classic cough, which we call a whoop, which is very characteristic of the disease. A child will stay ill for a long period of time and will be distressed and challenged to get enough oxygen into their lungs. They sound like they’re struggling to breathe. Parents will know that their child is not well. For adults, it may be the reason for a persistent cough. The main problem with whooping cough is that it can last for weeks — even months — if it’s not managed properly. If you believe you have pertussis, go see a doctor as soon as you can.

Does the pertussis vaccine require 95% coverage like measles to prevent spread for herd immunity?

The pertussis vaccine is protective, but the issue is that it doesn’t last. There is a waning of protection over time, unlike some other vaccines, and that means that we will often have to boost adults to make sure that they maintain protection to prevent them carrying the disease and passing it on to children. It is an effective vaccine. The efficacy, as we call it, the level of protection, is right up around 80% with the new formulations of the vaccines, and they’re proven to be very safe.

How do you convince people that pertussis vaccine is safe with all the attention on vaccine safety?

We know that the whooping cough vaccine is safe. We went through a re-appraisal of the vaccine around 40 years ago and developed a new, even safer form of the vaccine. This included large placebo-controlled trials. We’re always trying to improve vaccine safety. There always is a minor risk with any type of medication that some people can react to it. It’s very, very rare in the case of the whooping cough or pertussis vaccine. And we want to try to keep that safety record going in the sense that we are always looking out for any adverse events. There are very few. We have to be vigilant, but at the moment the pertussis vaccine is proving safe and protective.

Are you hoping to increase the number of adults and children who get a pertussis vaccine?

If we increase pertussis vaccine rates, the number of cases will drop. And that’s really where the proof lies for both safety and efficacy.