**3.4. Pregnant women: booster doses**

One of the strategies to reduce the transmission of pertussis to young infants, especially less than 6 months of age, is the introduction of Tdap vaccination in pregnant women between 27 and 36 weeks of gestation in all pregnancies (not just the first one). Vaccination of the pregnant woman is most effective when administered 28 days or more before delivery, when a greater number of antibodies are transferred to the fetus. No adverse events were reported for the mother or the newborn with this measure, except for a small significant increase in chorioamnionitis seen by Kharbanda in 2014 [47–50]. The transplacental transfer of vaccineinduced antibodies from the pregnant woman to the fetus before birth and through maternal breastfeeding after birth is the basis of the prenatal immunization [19]. If the mother is vaccinated with the aP vaccine during pregnancy, her maternal antibodies against pertussis will also be transferred to the newborn through breast milk [46].

and infants of mothers vaccinated for pertussis was adequate and protective, although their levels were slightly lower after the first three doses of the vaccine, and there was no difference in antibody levels after the first booster in the second year of life [10]. Monitoring the immunity of children vaccinated or not should be done regardless of age, in order to understand the long-

Clinical Experiences in Pertussis in a Population with High Vaccination Rate

http://dx.doi.org/10.5772/intechopen.75684

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Prenatal vaccination induces protection against pertussis by producing high levels of antibodies, which are transferred to the fetus. This strategy will protect newborns when they are vulnerable to the disease, which happens mainly in the period before they complete their

Vaccination in pregnant women is the most cost-effective strategy for disease prevention in young infants and unvaccinated newborns. It is more effective to vaccinate the pregnant mother than to vaccinate those interacting with the baby. The vaccine should be given in the second or third trimester of pregnancy, at least 15 days before delivery. This strategy should be adopted in countries with high or increasing morbidity and mortality of young infants due

The cocooning strategy consists of vaccinating the whole family and intimate contacts of the newborn, in addition to vaccination of the pregnant woman. It is important to remember that the vaccine takes 2 weeks to raise the antibodies to protective levels; therefore, the newborn is exposed to the transmission of the pertussis during this critical period [20]. Vaccination of household members is effectively provided as it is performed in a timely manner [16]. All caregivers of young infants (who feed, dress, and bathe them regularly) should also be considered for vaccination [46]. It is necessary to achieve adherence by all of those in contact with the newborn or young infant, in order to obtain the effectiveness of the cocooning strategy. It is important to note that the mother accepts this initiative better than the father of the child

In an American study of 115 young infants with severe pertussis, 72% had previously had contact with adults or children over 11 years of age who showed acute cough for 5 days or more, referred to in the last month. This contact was often with the mother. The fact that infants received a dose of aP did not protect them from the disease [46]. The route of contami-

It has been observed that infants and young infants with older siblings are also at increased risk for pertussis. Each older sibling of the young infant increases the chance of having pertussis 1.5 times more, speaking in favor of the hypothesis that the source of contamination is the

The American CDC recommends vaccination with a dose of Tdap for every adult and adolescent who have contact or who live with infants younger than 12 months of age [50]. Chile also adopted this strategy in 2011 with a significant impact: there was an 84% reduction in infant

mortality when comparing cocooning strategy with no action taken [3].

term impact and the real significance of these immunological findings [19].

primary vaccination schedule with all three doses of the vaccine [19].

and other relatives tend to accept it even more rarely [20].

nation was usually through a member of the family [6].

to pertussis [16, 60].

older sibling [12].

**3.5. Caregivers: cocooning strategy**

In 2012, vaccination of pregnant women in the third trimester of pregnancy was instituted by the American Centers for Disease Control and Prevention (CDC), regardless of their vaccination status, due to the loss of immunity a few months after booster vaccination. Several studies have attested the safety of dTap use in pregnant women [51, 52]. These studies showed that women vaccinated before pregnancy had less than 50% detectable antibodies against pertussis during gestation, which led to the adoption of the measure of vaccinating the woman at each gestation, regardless of her previous vaccination status [10, 53]. Vaccination in pregnant women between 27 and 36 weeks is more effective for the prevention of pertussis in young infants than vaccination in the second trimester of pregnancy. On the other hand, it is known that the vaccine given at the beginning of this period of 27–31 weeks is more effective in reducing pertussis in young infants. Efforts should be made for adequate vaccination schedule during prenatal consultations. Vaccination of 27–36 weeks is 85% more effective than Tdap postpartum vaccination [12, 51].

In the UK, vaccination was introduced in 2012 for pregnant woman between 28 and 32 weeks. In 2016, the country began recommending vaccination between 16 and 32 weeks, in order to improve the chance of vaccination to protect preterm infants, as well as to improve the level of maternal antibodies at birth. Later, vaccination during pregnancy protects the mother from developing the disease, giving some degree of protection to the newborn. Some studies have shown that women who were vaccinated after 32 weeks of pregnancy did not have the best level of passive protection for the newborn. In Belgium, the orientation for pregnant women is from 24 to 32 weeks of gestation [19, 25, 54, 55].

The timing of pregnant women vaccination is still controversial, with recent studies recommending it in the second trimester of pregnancy, while previous studies advocated for the third trimester [10, 52].

The recommendation of vaccination in pregnant women has expanded to several countries, such as Argentina, Belgium, Brazil, Colombia, El Salvador, Mexico, New Zealand, Australia, Switzerland, Ireland, the Czech Republic, Israel, Spain, and Greece [19].

It is known that the transfer of maternal antibodies to the newborn can interfere with the response of young infants to their own vaccination [56, 57], a phenomenon called blunting. This phenomenon depends on the type of vaccine antibody: the PT antibody increases after primary immunization, but the FHA antibody decreases in infants born from mothers vaccinated during pregnancy [19, 58, 59]. A study showed that the level of antibodies in the newborn and infants of mothers vaccinated for pertussis was adequate and protective, although their levels were slightly lower after the first three doses of the vaccine, and there was no difference in antibody levels after the first booster in the second year of life [10]. Monitoring the immunity of children vaccinated or not should be done regardless of age, in order to understand the longterm impact and the real significance of these immunological findings [19].

Prenatal vaccination induces protection against pertussis by producing high levels of antibodies, which are transferred to the fetus. This strategy will protect newborns when they are vulnerable to the disease, which happens mainly in the period before they complete their primary vaccination schedule with all three doses of the vaccine [19].

Vaccination in pregnant women is the most cost-effective strategy for disease prevention in young infants and unvaccinated newborns. It is more effective to vaccinate the pregnant mother than to vaccinate those interacting with the baby. The vaccine should be given in the second or third trimester of pregnancy, at least 15 days before delivery. This strategy should be adopted in countries with high or increasing morbidity and mortality of young infants due to pertussis [16, 60].
