WP6

Observational vaccine studies in Denmark 

 Given the excellent registers in Denmark, we will continue observational studies in Denmark focusing on the out-phasing of BCG and smallpox vaccine in the 1970s, and on the current child vaccination program.

 To document BCG and smallpox vaccinations we use data from the school health registers. So far, we have found that BCG reduced the risk of lymphomas by 51%55, smallpox vaccine reduced the risk of asthma by 45%18 and the risk of hospital admissions for infectious diseases by 16%19, and smallpox and BCG vaccination reduced the risk of hospitalization for HIV-infection by 65% (12-86%, unpublished).

 For the examination of currently used vaccines, the register of vaccinations has been linked to the DNPR and the NRMPS. So far, we have found that measles-mumps-rubella (MMR) vaccine protects against admission for respiratory syncytial virus (RSV), whereas there was no such effect of diphtheria-tetanus-pertussis-polio and H. influenzae b (DTPPHib) vaccine. DTPPHib had a sex-differential effect on RSV admissions, being associated with lower incidence in males than in females (unpublished). Hence, the Danish studies confirm the observations made in West Africa. These studies will be continued.

Deliverables

 Estimates of how BCG, smallpox vaccine and current vaccines affect the risk of hospital admissions and prescriptions.

Implications

 The smallpox vaccination studies may greatly advance the case for taking NSEs into consideration before withdrawing/reducing beneficial vaccines as may happen with the planned eradication of measles and polio. If results for MMR are confirmed, earlier MMR vaccination to reduce admissions should be tested in an RCT.

Ethics

 According to Danish law these register studies will only need approval from the DDPD.

PhD students

 The PhD students will be placed at the Center and supervised by Peter Aaby, Henrik Ravn, and other members of the CVIVA group. The PhD students’ academic focus will continuously be evaluated by CVIVA's steering committee. Research results will be published in leading international journals and in conference proceedings, and in all cases, the Center and the Danish National Research Foundation be thanked for support. The PhD students will participate in all key meetings and activities of the Center and contribute to the Center's general activities.