This study aims to establish an effective method to inform parents or close relatives of newborns about the risk of pertussis transmission to newborns and the advantages offered by the cocooning strategy (vaccinating those who are in close contact with the newborn) by assessing the factors that affect the parents' decision-making to accept pertussis immunisation.

Two phases are foreseen in the study. The 'questionnaire design' phase will be conducted in order to finalise the electronic questionnaire. The enrollment phase will involve the administration of the final web-based questionnaires to the subjects included in the enrollment phase.

The data generated in this study will be useful to inform parents of newborns about the advantages of vaccinating people who are in close contact with the newborn even before the baby is born in order to prevent the transmission of pertussis to the newborn.

No vaccine will be administered during this study.

Inclusion Criteria:

• Subjects who the investigator believes that, can and will comply with the requirements of this protocol (ability to understand the study objectives and the questions asked, and ability to operate a computer).
• Written informed consent obtained from the subject.
• Subjects aged ≥ 18 years at the time of study start who are either:

Contacts of newborns (aged ≤ 6 months). OR Expecting mothers in their last trimester of pregnancy or their partners, who will be in close contact with the newborn.

• Subjects who will be eligible for pertussis booster vaccination and have not received any pertussis vaccination in the last 2 years (before study start).

Exclusion Criteria:

• Subjects who have participated in the 'questionnaire design' phase (applicable only for subjects who will participate in the enrollment phase of the study).
• Subjects with a contraindication to pertussis vaccination.
• Subjects who declare to be in principle against vaccination.
• Subjects who declare to be in a chronic physical condition and not compatible with vaccination.
• Subjects with a history of pertussis in the last 5 years (before study start).
• History of non-response to pertussis vaccination.
• Subjects with mental deficiency.
• Subjects with unstable chronic health condition(s).

Subjects aged 18 years and above who are either contacts of newborns (aged ≤ 6 months) or expecting mothers in their last trimester of pregnancy or their partners, who will be in close contact with the newborn.