Pertussis vaccine is a vaccine that protects against whooping cough (pertussis). There are two main types: whole-cell vaccines and acellular vaccines. The whole-cell vaccine is about 78% effective while the acellular vaccine is 71–85% effective. The effectiveness of the vaccines appears to decrease by between 2 and 10% per year after vaccination, with a more rapid decrease with the acellular vaccines. The vaccine is only available in combination with tetanus and diphtheria vaccines (DPT vaccine). Pertussis vaccine is estimated to have saved over 500,000 lives in 2002. Vaccinating the mother during pregnancy may protect the baby. The World Health Organization and the US Centers for Disease Control and Prevention recommend all children be vaccinated for pertussis and that it be included in routine vaccinations. Three doses starting at six weeks of age are typically recommended in young children. Additional doses may be given to older children and adults. This recommendation includes people who have HIV/AIDS. The acellular vaccines are more commonly used in the developed world due to fewer adverse effects. Between 10 and 50% of people given the whole-cell vaccines develop redness at the injection site or fever. Febrile seizures and long periods of crying occur in less than 1% of people. With the acellular vaccines, a brief period of non-serious swelling of the arm may occur. Side effects with both types of vaccines, but especially the whole-cell vaccine, are less common in younger children. The whole-cell vaccines should not be used after seven years of age. Serious long-term neurological problems are not associated with either type. The pertussis vaccine was developed in 1926. It is on the World Health Organization's List of Essential Medicines.
Medical uses
Effectiveness Acellular pertussis vaccine (aP) with three or more antigens prevents around 85% of typical whooping cough cases in children. Compared to the whole cell pertussis vaccine (wP) used previously, the efficacy of aP declines faster. Multi-antigen aP has higher efficacy than old low-efficacy wP, but is possibly less effective than the highest-efficacy wP vaccines. Acellular vaccines also cause fewer side effects than whole-cell vaccines. Despite widespread vaccination, pertussis has persisted in vaccinated populations and is one of the most common vaccine-preventable diseases. The recent resurgence in pertussis infections is attributed to a combination of waning immunity and new mutations in the pathogen that existing vaccines are unable to control effectively. It is debated whether the switch from wP to aP has played a role in this resurgence, with two 2019 articles disagreeing with one another. Some studies have suggested that while acellular pertussis vaccines are effective at preventing the disease, they have a limited impact on infection and transmission, meaning that vaccinated people could spread the disease even though they may have only mild symptoms or none at all.
Children For children, immunizations are commonly given in combination with immunizations against tetanus, diphtheria, polio, and haemophilus influenzae type B at two, four, six, and 15–18 months of age.
Adults In 2006, the US Centers for Disease Control and Prevention (CDC) recommended that adults receive pertussis vaccination along with the tetanus and diphtheria toxoid booster. In 2011, they began recommending boosters during each pregnancy. The UK commenced routine vaccination of pregnant women in 2012. The program initially aimed to vaccinate women between 28 and 32 weeks (but up to 38 weeks) of pregnancy: later advise allowed maternal pertussis immunisation from week 16 of pregnancy. Since its introduction, the maternal pertussis immunisation programme has been very effective in protecting infants until they can have their first vaccinations at two months of age. During the first year of the maternal immunization programme in Britain, the average vaccine coverage in England was 64%, and vaccine effectiveness was estimated to be 91%. During 2012, fourteen infants died from pertussis in England and Wales; all were born before the introduction of the programme. Up to 31 October 2014, 10 deaths were reported in infants with confirmed whooping cough who were born after the introduction of the maternal programme. Nine of them were born to unvaccinated mothers, and all 10 were too young to have received a dose of pertussis-containing vaccine. The pertussis booster for adults is combined with a tetanus vaccine and diphtheria vaccine booster; this combination is abbreviated "Tdap" (Tetanus, diphtheria, acellular pertussis). It is similar to the childhood vaccine called "DTaP" (Diphtheria, Tetanus, acellular Pertussis), with the main difference that the adult version contains smaller amounts of diphtheria and pertussis components—this is indicated in the name by the use of lower-case "d" and "p" for the adult vaccine. The lowercase "a" in each vaccine indicates that the pertussis component is acellular, or cell-free, which reduces the incidence of side effects. The pertussis component of the original DPT vaccine accounted for most of the minor local and systemic side effects in many vaccinated infants (such as mild fever or soreness at the injection site). The newer acellular vaccine, known as DTaP, has greatly reduced the incidence of adverse effects compared to the earlier "whole-cell" pertussis vaccine; however, immunity wanes faster after the acellular vaccine than the whole-cell vaccine.
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