Pertussis cocoon strategy: would it be useful for Latin America and other developing countries?

Among vaccine-preventable diseases and deaths in children, pertussis is the most common cause in those countries where pediatric universal pneumococcal conjugate vaccination has been introduced in national immunization programs. Despite good vaccination coverage rates of the primary series and booster doses in children from many countries, outbreaks and epidemics still occur. Owing to waning immunity over the years among adults and adolescents, these individuals including new parents are the most common source of transmission to young infants and, therefore, have become important target groups for selective immunization strategies [1–5]. Despite the availability of new acellular pertussis vaccines (Tdap) for these groups and accumulative experience with their use during the last decade, the disease burden remains considerable in many countries. The pertussis cocoon strategy consists of vaccinating with Tdap: women, their partners and other close contacts of young infants. It has been recommended by the Advisory Committee on Immunization Practices in the USA and many other health authorities in different countries as a potential useful strategy to decrease the impact of the disease. If perfectly implemented, cocoon strategy has been estimated to reduce pertussis cases in young infants by 70%. In 2008, specific immunization recommendations for pregnant and postpartum women were published by the Advisory Committee on Immunization Practices [6] and since then updated recommendations have been released [7]. Whenever possible, it is preferred that women get vaccinated with Tdap before getting pregnant. If not, postpartum vaccination of new mothers and their couples has been recommended until more recently, when Tdap during pregnancy is recommended, preferably during the third or late second trimester (after 20 weeks of gestation). Compared with postpartum Tdap vaccination, its use during pregnancy has been found to be more cost effective and prevents greater number of infant cases and fatalities [7]. However, if not given to pregnant women, postpartum Tdap should be applied as soon as possible to women, as immediate antibody response to the vaccine in them and breast milk antibodies are not achieved early in the first week of life. In an interesting recent kinetics study measuring serum and breast milk antibodies to the different components of Tdap in childbearing and postpartum women, Halperin et al. showed how the increase to reach peak antibody levels requires at least 1–2 weeks, and therefore the infant would not be protected in the first 2 weeks of life [8]. Gall and colleagues demonstrated the potential benefit of giving Tdap during Pertussis cocoon strategy: would it be useful for Latin America and other developing countries?