Can my employer ask about my health, sickness or vaccinations?

Health data at work is Art. 9 material processed only through employment-law gates (Art. 9(2)(b)) — and those gates are engineered around a firewall: the occupational physician. What the employer may know: that you are sick, expected duration, work capacity — “fit / unfit / fit with adjustments”. What stays behind the firewall: the diagnosis, your medications, your history — the doctor advises capacity; HR never lawfully demands “what do you have?”, and answering is your choice, not your duty (limited infection-protection duties in food/care sectors aside, set by national law). Sick-note regimes vary nationally, but even where notes flow to the employer they certify incapacity, not illness. Vaccination status: outside narrow statutory sectors (healthcare in some countries), employers demanding jab records lack a basis — the pandemic-era rules that briefly said otherwise were exceptional law, mostly lapsed; a blanket vaccination register in HR is a standing Art. 9 violation. Interviews: health and pregnancy questions are off-limits, and the established doctrine in several countries is blunt — an unlawful question earns no truthful-answer duty. Your rights when it goes wrong: access to your personnel file (see what health data leaked into it), erasure of unlawfully-collected detail, works council and DPA escalation — plus the insurer rules when income-protection claims pull the same trick from the other side.