Identification of determinants associated with uptake of the first dose of the human papillomavirus vaccine in Denmark.

Background: The human papillomavirus vaccine (HPV vaccine) was introduced into the Danish Childhood Vaccination Programme in 2009. Following a national debate questioning the safety of the vaccine, the coverage decreased from an uptake of >90% for the first dose of the HPV vaccine to an uptake of 52% in girls born in 2003. The aim of this study was to identify changes in determinants for HPV vaccine hesitancy in the period when the debate spiraled and to identify determinants for specific hesitancy towards the HPV vaccine among girls who received the second dose of the measles, mumps and rubella vaccine.

Methods: We included girls born in the period 1999-2003 who were residing in Denmark between their 12th and 13th birthday (n = 161,528). Data from the Danish Vaccination Register were linked with demographic data from the Danish Civil Registration System. We used multiple logistic regression models to identify associations between determinants and the uptake of the first dose of the HPV vaccine (HPV1).

Results: For girls born in 1999-2000, low uptake was seen in children of increasing birth order, young or old age of mother, non-Danish origin, low uptake of other childhood vaccines, and in girls living with one parent. For girls born in 2001-2003, most of these determinants of low uptake became less significant. Birth order and origin showed different tendencies when comparing birth cohorts 1999-2000 with birth cohorts 2001-2003.

Conclusions: We found demographic disparities in the uptake of HPV1 that were generally in line with existing literature. More importantly, the results indicate that determinants for hesitancy towards the HPV vaccines changed during a period of intense public debate regarding the safety of the HPV vaccine. This may indicate that the public concerns over safety disproportionally affect those who trusted vaccines prior to the debate.