DPT vaccine

The DPT vaccine or DTP vaccine is a class of combination vaccines to protect against three infectious diseases in humans: diphtheria, pertussis (whooping cough), and tetanus (lockjaw). The vaccine components include diphtheria and tetanus toxoids, and either killed whole cells of the bacterium that causes pertussis or pertussis antigens. The term toxoid refers to vaccines which use an inactivated toxin produced by the pathogen which they are targeted against to generate an immune response. In this way, the toxoid vaccine generates an immune response which is targeted against the toxin which is produced by the pathogen and causes disease, rather than a vaccine which is targeted against the pathogen itself. The whole cells or antigens will be depicted as either "DTwP" or "DTaP", where the lower-case "w" indicates whole-cell inactivated pertussis and the lower-case "a" stands for "acellular". In comparison to alternative vaccine types, such as live attenuated vaccines, the DTP vaccine does not contain any live pathogen, but rather uses inactivated toxoid (and for pertussis, either a dead pathogen or pure antigens) to generate an immune response; therefore, there is not a risk of use in populations that are immune compromised since there is not any known risk of causing the disease itself. As a result, the DTP vaccine is considered a safe vaccine to use in anyone and it generates a much more targeted immune response specific for the pathogen of interest.

In the United States, the DPT (whole-cell) vaccine was administered as part of the childhood vaccines recommended by the Centers for Disease Control and Prevention (CDC) until 1996, when the acellular DTaP vaccine was licensed for use.

Diphtheria and tetanus toxoids and whole-cell pertussis (DTP; now also "DTwP" to differentiate from the broader class of triple-combination vaccines) vaccination was licensed in 1949. Since the introduction of the combination vaccine, there has been an extensive decline in the incidence of pertussis, or whooping cough, the disease which the vaccine protects against. Additionally, the rates of disease have continued to decline as more extensive immunization strategies have been implemented, including booster doses and increased emphasis on increasing health literacy.

In the 20th century, the advancements in vaccinations helped to reduce the incidence of childhood pertussis and had a dramatically positive effect on the health of populations in the United States. However, in the early 21st century, reported instances of the disease increased 20-fold due to a downturn in the number of immunizations received and resulted in numerous fatalities. During the 21st century, many parents declined to vaccinate their children against pertussis for fear of perceived side effects, despite scientific evidence showing vaccines to be highly effective and safe. A study published in 2009 concluded the largest risk among unvaccinated children is not the contraction of side effects, but rather the disease that the vaccination aims to protect against.

DTP vaccines with acellular pertussis (DTaP; see below) were introduced in the 1990s. The reduced range of antigens causes fewer side effects, but results in a more expensive, shorter-lasting, and possibly less protective vaccine compared to DTwP. High-income countries have mostly switched to DTaP. As of 2023, global production of aP remains limited.

In 2016, the US Centers for Disease Control and Prevention (CDC) reported that 80.4% of children in the US had received four or more DTaP vaccinations by 2 years of life. Vaccination rates for children aged 13–17 with one or more TDaP shots was 90.2% in 2019. Only 43.6% of adults (older than 18 years of age) have received a TDaP shot in the last 10 years. The CDC aimed to increase vaccination rate among 2-year-olds from 80.4% to 90.0%

The World Health Organization (WHO) estimated that 89% of people globally had received at least one dose of DTP vaccine and 84% had received three doses of the vaccine, completing the WHO-recommended primary series (DTP3). The WHO tracks DTP3 completion rates among one-year-olds on a yearly basis. The yearly DTP3 completion rate is considered a good proxy for the completeness of childhood vaccination in general, and numbers of children who have not received a first dose of DTP are used as a proxy for those who are not reached by vaccination programs at all (termed zero-dose children).

DTaP and Tdap are both combination vaccines against diphtheria, tetanus, and pertussis. The "a" indicates that the pertussis toxoids are acellular, while the lower-case "d" and "p" in "Tdap" indicate smaller concentrations of diphtheria toxoids and pertussis antigens.