Pertussis, commonly known as whooping cough, is a highly contagious respiratory disease caused by the bacterium Bordetella pertussis.¹ Despite the availability of vaccines, pertussis remains a significant public health issue, particularly affecting infants and young children.² This article examines the historical and recent trends in pertussis hospitalisation rates, with a focus on the current outbreak in the United Kingdom (UK), using data and studies from reputable sources such as the British Medical Journal (BMJ), National Institute for Health and Care Excellence (NICE), and PubMed.

Historical trends in pertussis hospitalisation rates

1950s to 1980s: decline due to vaccination

The introduction of the whole-cell pertussis vaccine in the 1940s led to a significant decline in pertussis cases and hospitalisations globally. In the UK, the widespread adoption of the DTP (diphtheria, tetanus, and pertussis) vaccine in the 1950s and 1960s resulted in a dramatic reduction in the incidence and severity of the disease. By the 1980s, pertussis had become relatively rare, with only sporadic outbreaks occurring (NCBI).

1990s to early 2000s: resurgence of cases

Despite high vaccination coverage, pertussis began to resurface in the 1990s. This resurgence was attributed to several factors, including waning immunity from the acellular pertussis vaccines introduced in the 1990s, increased awareness and better diagnostic methods, and potential genetic changes in Bordetella pertussis. Studies have indicated that immunity from both the vaccine and natural infection diminishes over time, necessitating booster doses to maintain protection.

Mid-2000s to 2010s: cyclical outbreaks

The period from 2000 to 2010 witnessed cyclical outbreaks of pertussis in the UK and other developed countries. From 2002 through 2005, there were 156 hospitalisations/100,000 infants less than 3 months old due to pertussis in England and Wales.³ The largest outbreak occurred in 2012, with over 9,000 confirmed cases and 14 infant deaths in the UK.⁴ This led to the implementation of a maternal immunisation program, which significantly reduced the incidence of pertussis in infants too young to be vaccinated.

Recent trends: The 2020s and the current outbreak, and the impact of the COVID-19 pandemic

The COVID-19 pandemic had a profound impact on the transmission dynamics of infectious diseases, including pertussis.⁵ Public health measures such as lockdowns, social distancing, and mask-wearing led to a temporary decline in pertussis cases. However, as these measures were relaxed, pertussis cases began to rise again, highlighting the need for ongoing vaccination and surveillance efforts.

Figure 1: Laboratory confirmed cases of pertussis by age group in England: 2018 to 2023 (provisional data). 

The 2023-2024 Outbreak in the UK

In late 2023 and early 2024, the UK experienced a significant resurgence of pertussis cases, leading to increased hospitalisations. Data from the UK Health Security Agency (UKHSA) indicated a sharp rise in cases among adolescents and adults, who can act as reservoirs for the disease and transmit it to unvaccinated infants.⁶ Preliminary data showed over 3,000 hospitalisations due to pertussis in the past year, with the majority of cases in infants under six months old.

Contributing factors to the resurgence

Several factors have contributed to the recent resurgence of pertussis and the associated increase in hospitalisation rates:

• Waning Immunity: Immunity from the acellular pertussis vaccine decreases over time, necessitating booster doses to maintain protection. This is particularly important for adolescents and adults, who can transmit the infection to vulnerable infants
• Vaccine Hesitancy: Pockets of under-vaccinated populations due to vaccine hesitancy have facilitated the spread of pertussis. Public health campaigns are essential to address misinformation and increase vaccine uptake¹
• Improved Surveillance and Reporting: Enhanced diagnostic methods and better reporting systems have led to an apparent increase in pertussis cases. This improvement in detection does not necessarily indicate a true rise in incidence but reflects better surveillance
• Genetic Variations in the Pathogen: Genetic changes in Bordetella pertussis might affect vaccine efficacy. Ongoing research is investigating these variations and their impact on vaccine performance

Summary

Pertussis (whooping cough) remains a major public health concern in the UK, particularly for infants. After a sharp decline in hospitalisations due to vaccination in the mid-20th century, cases resurged in the 1990s and have since followed cyclical patterns. A major outbreak in 2012 led to the introduction of maternal immunisation, which helped reduce infant cases.

However, the COVID-19 pandemic temporarily disrupted pertussis transmission, and cases have surged again post-pandemic. The 2023–2024 outbreak in the UK saw over 3,000 hospitalisations, mostly in infants under six months. Contributing factors include waning vaccine immunity, vaccine hesitancy, improved surveillance, and potential genetic changes in Bordetella pertussis. Ongoing vaccination and public health efforts remain critical.