Vaccine
Volume 33, Issue 17, Pages 1999-2096 (21 April 2015)
http://www.sciencedirect.com/science/journal/0264410X/33/17

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Pertussis in infants under one year old: Risk markers and vaccination status—A case-control study
Original Research Article
Pages 2073-2078
Chen Stein Zamir, Dana Bardugo Dahan, Hanna Shoob
Highlights
– Low birthweight and high birth order were found to be independent risk markers for pertussis in young infants.
– A third of reported pertussis cases in infants occurred under age 2 months (currently recommended for the 1st pertussis vaccine dose).
– Reported pertussis cases over age 2 months were more likely to be unvaccinated and to have delayed vaccinations.
– In 2-4-month-old infants, 1 dose of pertussis vaccine gave significant protection against pertussis overall and pertussis hospitalization.
– The pertussis vaccine effectiveness increased with the number of vaccine doses.