The retrospective analysis of confirmed infant pertussis cases in parts of the UK performed by Public Health England (PHE), a government body that researches health improvement and disease prevention, found that among 88 cases of pertussis in children aged three months or less where the moms' vaccination status was known, 76 cases occurred among infants who had not been exposed the vaccine—either in utero or shortly after birth—while only 12 occurred in infants whose mothers had received the vaccine at least seven days before giving birth. Two cases occurred among infants exposed to the vaccine prenatally only a week prior to birth or shortly after. On the basis of further calculations, the scientists estimated that maternal vaccination at least a week before delivery was 90% effective in protecting infants less than three months old against whooping cough. This is good news for the UK, which saw 9,700 cases of whooping cough and 14 infant deaths related to the disease in 2012. As the unsettling statistics rolled in, the UK Health Protection Agency (now part of PHE) implemented a five-year program to vaccinate all pregnant women in the country during their third trimester with the dTaP, a vaccine that contains a low dose of diphtheria toxin along with polio, tetanus and pertussis antigens. As of July, that program has now been extended another five years, though GlaxoSmithKline will replace Sanofi-Pasteur as the UK's official dTaP provider. In the US, the ACIP continues to recommend the Tdap, a similar formulation that lacks polio antigens and is offered by both companies.
“It was truly the only and by far the most effective mechanism we could come up with,” says ACIP member, Mark Sawyer, a pediatric infectious disease specialist at the University of California, San Diego. At the height of the 2012 epidemic, it became clear to Sawyer and the rest of the ACIP that their recommendation to vaccinate close family members of newborns, a strategy called cocooning, was not doing enough. In 2011, the ACIP suggested that pregnant women who were due for the Tdap (an adult booster for DTaP, the full-dosed diphtheria and tetanus vaccine) should get it. After data came out indicating that immunity to the Tdap waned between pregnancies, they changed the recommendation to include all women regardless of vaccination history.
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