**3.3. Adolescents and adults: booster schedule**

awareness, increased global laboratory tests, and increased sensitivity of diagnostic methods, as well as by the use of PCR amplification. Recurrent natural cycles may be more visible in countries where surveillance is more sensitive and where disease control in recent years has

Data from only five of these countries (Australia, Chile, Portugal, the USA, and the UK) supported the hypothesis of a real resurgence in pertussis-related morbidity in recent years compared to previous periods of time. Only one country that used wP vaccine against pertussis, Chile, reported a resurgence. For the time being, the increase in cases can be attributed to a sustained decrease in vaccine coverage, to variable coverage at the district level, to changes in surveillance practices, as well as to problems with the specificity of diagnostic tests. The increase in infant cases was noteworthy and associated with increased disease mortality. However, since this was based on fluorescent antibody test data alone (which is known to have problems with specificity), more data will be needed for a better characterization of the

There is a wide variety of vaccine calendars in the world. By 2015, 86% of children worldwide (116.1 million) received three doses of diphtheria, tetanus, and pertussis (DTP) vaccines. However, to reach coverage of 95% or more, 13.5 million unvaccinated children should be vaccinated annually, and an additional 6 million children with incomplete vaccination should complete the timeline. Restricted access and missed opportunities for vaccination remain a

The increased incidence of whooping cough in countries with high vaccine coverage is alarming, with rates only previously seen in 1950. The protection of newborns is urgently needed,

Vaccination in newborns is not an option at the present time, both due to the immaturity of the immune system of the newborn and its weak response to the vaccine. Besides these factors, the vaccine against pertussis may also interfere with the newborn's response to the hepatitis B vaccine. For the protection of the newborn, we currently can resort to three related

The WHO recommends three doses of vaccine in the primary series, the first dose being given at 6 weeks of age (at the latest at 8 weeks of age). The second dose should be given 4–8 weeks after the first one. The last dose should be given at 6 months of age or at any opportunity after. Delaying the third dose may reduce protection against severe illness in the first year of life. A booster dose is recommended after 1 year of age, preferably in the second year of life, 6 months after the primary vaccination scheme. In countries that use aP vaccine, protection

challenge worldwide, as well as for middle- and upper-income countries [41].

especially during the period between birth and the first dose of the vaccine [10].

strategies: cocooning, booster schedule, and vaccination of pregnant women [10, 42].

**3.2. Children: primary vaccination and booster schedule**

generally been good.

32 Pertussis - Disease, Control and Challenges

problem [3, 39].

**3.1. Newborns**

**3. Vaccination and control strategies**

The acellular vaccine was introduced in 1992 in the American calendar, and in 1997 it was already part of the entire childhood calendar (2, 4, 6, and 15 months and 4–6 years). In 2006, a booster dose was introduced at 11–12 years old. Despite this, there was a large outbreak in 2012 in children vaccinated with the acellular vaccine, probably due to the loss of immunity, lower immune response induced by the aP, increased awareness and notification, as well as improved diagnostic techniques, and possibly genetic alterations of the bacteria [26].

One of the reasons for the increase in pertussis is the loss of immunity induced by the vaccine or by infection among adolescents and adults. This leads to the discussion about the need for changes in the vaccine calendars of adolescents and adults. In countries with high vaccination coverage, there has also been an increase in pertussis cases in adolescents and adults in recent years, which is one of the causes of the onset of diseases in young infants, so a vaccine booster in adolescence and adulthood is recommended in order to reduce the spread of the disease among young infants [20].

The duration of immunity of the wP vaccine is 4–12 years, and the aP protection begins to diminish after 4–5 years. This led to the need of a booster dose in the adolescence (from 8 to 11 years), because adolescents present low levels of antibodies, which increase later in life (from 12 to 15 years) due to natural infection [44].

Although a booster dose in adolescence has been shown to decrease the disease in adolescents, this is generally not recommended as a means of controlling disease in infants. Introduction of reinforcements in adolescents and/or in adults should only be done after evaluation of local epidemiology [16, 43]. Adult vaccination in most countries with high vaccination coverage is done with dT, and even when done with dTap, as in the USA, this occurs in only 14.2% of adults who have done so in the last 7 years [45].

One of the risk factors associated with pertussis in young infants is the presence of a household contact, usually parents, siblings, or caregivers, with a cough for 5 days or more [46].
