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Scientists react to a rise in whooping cough cases in the UK.
Prof Adam Finn, Professor of Paediatrics, University of Bristol, said:
“Receiving whooping cough vaccine in pregnancy is a very effective way to protect newborns from the disease which is most dangerous during the early weeks and months of life. Babies will get protection from receiving vaccines themselves, but this is only fully in place when they are about 5-6 months old. Like many infections, whooping cough comes in waves or epidemics and there is a serious epidemic happening at the moment.
“Unfortunately, a significant proportion of pregnant women have not been receiving the vaccine and so we are now seeing severe cases among the infants of these women. While the reasons for this are certainly multiple and complex, we owe it to these mothers and their children to ensure that they are offered both timely vaccination and the information and explanation, from someone they understand and trust, to enable them to make the right decision and avoid this dreadful and entirely preventable disease by being immunised.”
Dr David Elliman, Consultant in Community Child Health at Great Ormond Street Hospital, said:
“The rise in cases of whooping cough has inevitably resulted in a rise in deaths of those at greatest risk of getting the disease most severely – young babies. This is not confined to the UK, with other countries seeing similar rises in cases. There are a number of factors that are likely to be contributing to the situation.
“The measures taken to control COVID-19 also suppressed many other diseases, whooping cough amongst them. Since these measures have been lifted there has been a bounce back in many of these diseases.
“Infants start their vaccinations at 8 weeks and have further doses at 12 and 16 weeks, followed by a booster at 3 years 4 months. However, this does not protect very young babies. The best way to do that is by immunising pregnant women during pregnancy. Over the last ten years or so there has been a small but steady decline in the uptake of vaccines in general. This includes those providing protection against whooping cough. The NHS is going through a period of turmoil and all services are under considerable pressure. This has had a part to play. There is no evidence that the low uptake of whooping cough vaccine in pregnancy is due to women declining the vaccine. More likely is a lack of clarity as to who is responsible for giving it – primary care or maternity.
“While the vaccines against whooping cough are not 100% protective, they reduce the chances of babies dying enormously. Parents should ensure that their babies are immunised on time, but as importantly that they get the vaccine when pregnant.
“The rise in cases of measles and pertussis and the sad deaths of 5 babies in the first three months of this year, should be a wakeup call to the NHS. For too long, successive governments have paid lip service to the importance of preventative health care. It is now time that appropriate resources are provided to back up the rhetoric. In addition, there should be clarity about who is responsible for maternity immunisations.”
Professor Andrew Preston from the University of Bath’s Milner Centre for Evolution, said:
“Pertussis vaccination of infants in the UK is given at 2, 3 and 4 months of age. This is followed up by a preschool booster. The infant vaccine is part the ‘6 in 1’ shot covering whooping cough, diphtheria, hepatitis B, Haemophilus influenzae, polio and tetanus. Infants also receive rotavirus and meningococcal B (2 months), pneumococcus and rotavirus (3 months) and meningococcus B (4 months).
“This set of vaccinations is critical to protecting infants against this array of serious diseases. The success of the vaccination programme is evident by the decline in the incidence of these diseases in infants and young children following the implementation of each vaccine.
“For many decades whooping cough was considered a disease solely affecting babies and young children because it is largely only this age group that present with classic whooping cough. However, it is now evident that the causative agent, the bacterium Bordetella pertussis, infects all age groups but that in older adolescents and adults the main presentation is likely to be chronic cough of varying severity although in most cases lasting weeks.
“Vaccination against whooping cough was first implemented in the UK (and much of the Western world) during the late 1940’s and 1950’s. The first vaccines were ‘whole cell’, in which the bacteria themselves were inactivated and formulated into the vaccine. These vaccines induced strong protective immunity against disease in infants and children but were associated with some side effects, particularly some fever and injection site soreness, likely due to the very robust immune response to some components of the bacterial cells in these vaccines.
“During the 1960’s and early 1970’s more serious sequelae, including infant neurological complications, started to be associated with the pertussis vaccines, reducing public confidence and acceptance such that coverage fell to low levels and led to several large outbreaks in the UK in the late 70’s. During this time, a second generation of pertussis vaccines were developed. These ‘acellular vaccines’ are comprised of several highly purified proteins of the bacterium. In extensive trials they proved effective at protecting babies and children against whooping cough but displayed improved safety in terms of reduced side effects. The acellular vaccines replaced the whole cells vaccines in most developed countries. In the UK, acellular vaccines have been used for the entire infant vaccination programme since 2004.
“It was evident that immune response induced by the acellular vaccines, while protective for youngsters, was different to the immunity generated by either infection or the whole cell vaccines. Over time it became clear that the acellular vaccine induced immunity waned (wore off) more quickly that that induced by whole cell vaccines such that adolescents and older children became susceptible to infection. However, by that age infection causes mainly chronic cough and is not considered a dangerous infection.
“The switch to the use of acellular vaccines has been attributed to a resurgence in whooping cough cases around the world, but particularly those countries that use those vaccines, with large outbreaks occurring 8-12 years after the switch. The current thinking is that while babies are still protected from disease, the earlier waning of immunity leads to more infections in the population, with greater circulation of the bacterium. This creates an increased risk of infection for all ages, including highly susceptible newborns too young to have developed immunity from vaccination.
“The UK experienced a major outbreak in 2011-2012 with over 10 000 cases notified in 2012 and a number of deaths in young infants. In response to the outbreak, the UK piloted the use of a maternal booster vaccination, given to pregnant women during pregnancy but after the 20 week scan, with the aim of protective antibodies generated by the mother being passed via the placenta to the foetus and providing protection from birth until the infant has developed their own vaccine-induced immunity.
“The maternal booster programme showed early signs of efficacy and has been in place ever since, with clear evidence of protection of newborns from this booster.
“The mitigations used during the pandemic reduced the incidence of all respiratory diseases, not just COVID, leading to almost no reported cases of whooping cough during that time. As with other respiratory disease, the incidence has been rebounding since the end of restrictions, but is clearly surging at the moment (see the UKHSA announcement yesterday).
“This has coincided with a period of reduced vaccine uptake both for infants and pregnant women. It is noticeable of the tragic deaths of 5 infants during Jan-Mar of this year, all were under 3 months of age, so those for which maternally-derived immunity is critically important.
“The latest vaccination coverage figures show a very worrying drop since the pandemic. The reasons have been much discussed, including interruption to health services that have been difficult to fully restart, high levels of mistrust of health services and of vaccines in some sections of society, including religious and cultural groups.
“The average figures for maternal vaccine uptake was 59.5% for December 2023. This is down from the high of close to 70% in the first few years of the programme. However, it hides alarming disparities between regions across the country. The rates in some urban and inner city regions have been lower than national averages for some time, but rates of coverage as low 25% in north central London is very worrying, meaning large numbers of infants have little to no protection against whooping cough just when the level of disease is surging. The low levels of vaccine uptake extend to numerous other city regions but even in those areas with the highest level of coverage, there is still ample scope for increasing the level of vaccination as the increase in cases has been observed nationwide.
“In addition, while not on the scale of the reduction in maternal vaccination, there has been a reduction in coverage of the infant vaccinations, from close to 97% coverage in 2013 to around 93% at the end of 2023, with a steady decrease over that whole period indicating a long-term trend. This leaves those unvaccinated children without protection and at risk of disease.
“It is clear that there is an urgent need for a major push to increase awareness of the current high level of risk of whooping cough among infants, ensuring ready access to vaccination while recognising all of the barriers to vaccination that were evident during the pandemic.”
Professor Paul T. Heath, Director of the St George’s Vaccine Institute, University of London, said:
“Sadly, the 5 reported deaths in infants with pertussis in the first quarter of 2024 is unsurprising given the fall in maternal and infant vaccine coverage and the well documented rise in pertussis cases in all ages, especially in young infants. These cases are tragic, but they are preventable. They occur too early however, to be prevented by infant pertussis vaccination, so these young infants are reliant on their mother being vaccinated – ideally after 20 weeks gestation, but can be done from any time after 16 weeks. The impact of maternal vaccination on severe disease is clear: of the 26 deaths (including these 5 deaths) that have occurred in young infants since the maternal vaccine program began in 2012, nearly all of them (21) were born to unvaccinated mothers; implying a very high vaccine effectiveness (92%).
“Midwives and obstetricians in particular, as well as GPs and primary care teams should ensure that pregnant women are aware of pertussis and have been offered all opportunities to receive a pertussis vaccine. Babies should be vaccinated as soon as they become eligible for infant doses (at 8, 12 and 16 weeks of age) and those that miss vaccination should have the opportunity to be caught up at the earliest opportunity.”
Professor Andrew Preston from the University of Bath’s Milner Centre for Evolution, said:
“Whooping cough is a bacterial disease of the respiratory tract. Classic whooping cough, or pertussis, is most often observed in babies and young infants and in the very young can give rise to serious, sometimes fatal, complications. Infection affects all age groups, often manifesting as chronic cough in adults. While this cough can go on for weeks it rarely results in serious illness in adults.
“Vaccination against whooping cough is part of the infant vaccination scheme, and in the UK babies receive these vaccinations at 2, 3 and 4 months of age, followed by a pre-school booster. In response to a very large outbreak in 2011-2012, the UK introduced a booster vaccination for pregnant women. The antibodies generated by this can pass to the foetus and provides protection to the baby during the critical period between birth and the development of protection from the infant vaccinations.
“While these vaccines provide excellent protection against serious whooping cough disease, the level of immunity they afford reduces over time meaning that by adolescence, many people are susceptible to infection.
“Cases of whooping cough peak every 4 or so years. The COVID-19 pandemic saw a dramatic fall in the incidence of whooping cough (and other respiratory infections) due to the greatly reduced mixing of people during that time. Cases have been rising since the end of restrictions and a peak year had been expected to arise soon. However, vaccination rates in infants have declined compared to pre-pandemic levels, down from over 96% coverage to just under 93% last year. Likewise, uptake of the maternal booster dropped from a high of 70% to under 60%. This results in many more young babies and infants susceptible to infection. It is tragic to see babies dying from whooping cough and with cases on the rise it is vital for vaccination rates to recover.”
Dr Michael Head, Senior Research Fellow in Global Health, University of Southampton, said:
“This new data alas illustrates just how serious whooping cough is – it can and does kill babies.
“Whooping cough can have a very long infectious period of around 2-3 weeks, i.e. the period of time when an infected individual is able to transmit the bacteria onto others. Thus, there may be plenty of opportunities for people to mix, transmission to occur, and for there to be an infection of a vulnerable individual, such as a baby.
“A high coverage of vaccination is vital in reducing transmission within populations. Vaccine uptake in young children and for expectant mothers during pregnancy is so important. The vaccine is safe, and extremely effective.”
Dr Michael Head, Senior Research Fellow in Global Health, University of Southampton, said:
“A drop in vaccination coverage will be a key factor contributing to this rise in cases of whooping cough. It’s vital that vulnerable groups such as babies and pregnant women are up to date with their recommended immunisations, and that includes the pertussis vaccine. Whooping cough can be a very severe infection, potentially fatal to babies who become infected.
“Outbreaks can occur in cycles, so we tend to see these rises in cases every few years. The reasons for that are not fully understood, but population-level waning immunity is likely to contribute to that, hence why a high coverage of vaccination is so important.
“As a disease, whooping cough is as infectious as measles, and more infectious than COVID-19. This is in part due to a long period where the infected individual can be infectious, i.e. able to transmit the bacteria onto others. Thus, with a larger pool of susceptible people, there is increased likelihood of an outbreak being sustained.”
Possibly helpful references
Green Book about pertussis vaccination
Data on the whooping cough outbreak
https://www.gov.uk/government/publications/syndromic-surveillance-weekly-summaries-for-2024
Infectiousness of pertussis, https://www.ecdc.europa.eu/en/publications-data/expert-consultation-pertussis#:~:text=Pertussis%20is%20a%20highly%20contagious,R0)%20of%2015%E2%80%9317.
As compared with e.g. measles, https://theconversation.com/measles-why-the-world-health-organization-has-declared-it-an-imminent-global-threat-195499 (COI – I wrote that Conversation article)
Prof Paul Hunter, Professor in Medicine, University of East Anglia (UEA), said:
“This is a complex issue and I do not think we have a full understanding, but my view is that it [the rise] is a combination of factors.
“For most adults the Whooping Cough is not life threatening, though can be very unpleasant. The chronic cough can be associated with increased risk of urinary incontinence, especially in women. Other complications are uncommon. However, in young children the risk is greater, and we do need to be concerned about the risk to babies.
“The infection can affect anyone who is not vaccinated and even some that are. However, the main risk of death or severe long-term complications is seen in young children, especially those under three months old. It is this age group that are most at risk of death and developing longer term problems such as brain damage. The problem is that this age group is too young for the vaccine in most circumstances. That is why we offer vaccine to pregnant women. Not to protect them but to protect their babies during the riskiest first months of life. Vaccine uptake in pregnant women has been falling quite markedly in recent years (figure 2).
“This is a chronic repeated bouts of coughing which can be so bad that people feel it a struggle to breath in again.
“It used to be much more common in the last century up until the vaccine was introduced. However, this current year looks like we may see more cases than we have seen in any of the last 40 years.”
Figure 1.
Figure 2.
Declared interests
Dr Elliman: No conflicts of interest.
Prof Heath is a member of the JCVI but is expressing his own views.
Dr Michael Head: No conflicts of interest.
For all other experts, no reply to our request for DOIs was received.