Historical clue formulations

• Certain shot, colloquially — 2026-07-31
• Shot that produces an immune response to a virus, slangily — 2024-12-02
• Shot at a doctor's office, slangily — 2024-05-28
• Shot in the arm, slangily — 2024-02-04
• Inoculation, slangily — 2023-08-01
• Preventive medicine, slangily — 2019-12-01