Non-specific protective effects resulting from the BCG vaccine appear to be paternally inheritable. Since the BCG vaccine is known to induce trained immunity, epigenetics might explain the fathers' contribution to the immune profile of their offspring. Epigenetic inheritance in mice has recently been demonstrated, but is not established in humans yet. By studying the DNA methylation profile of sperm cells after BCG vaccination, we aim to gain insight into the possibility of epigenetic inheritance in human males.

Inclusion Criteria:

• Healthy
• Male
• Age 18-25 years (at the moment of trial start)

Exclusion Criteria:

• Any systemic disease or conditin, or the use of systemic medication (with the exception of non-threatening alelrgies, e.g. hay fever)
• Smoking or drug use
• Prior BCG vaccination
• Other vaccination four weeks prior to trial start or four weeks after the first study visit (no vaccine in the same arm as the BCG vaccine for three months)
• Acute illness two weeks prior to trial start
• Known allergy or history of anaphylaxis/other serious adverse reaction to any vaccine
• Participation in another drug trial
• Legally incapacitated or unwilling to provide informed consent

The purpose of this study is to study sperm cells, therefore only male individuals can participate