How chickenpox spreads

An infected person can pass varicella to someone who is not immune through shared air during close indoor contact, coughing, sneezing, or contact with blister fluid. Transmission can happen before the rash is easy to recognise, so people may be exposed before a diagnosis is made. New blisters can appear in waves, and infectiousness continues until every lesion has dried and crusted. Shingles is caused by the same virus later reactivating in someone who has previously had chickenpox; it can pass the virus to a non-immune person through blister fluid, causing chickenpox rather than shingles.

Keep the unwell person away from school, childcare, work, and close household contact with pregnant people, newborns, and anyone with a weakened immune system. Improve ventilation, avoid sharing towels or clothing, and wash hands after touching the rash. Do not deliberately expose someone to chickenpox. Ask a clinician about chickenpox vaccination after a possible exposure, because timing and personal circumstances affect the advice. Tell the clinic about the exposure before attending.

Contact a GP promptly after exposure if the person is pregnant, very young, immunocompromised, or unsure whether they are immune. Seek urgent help for breathing difficulty, confusion, severe weakness, dehydration, or a rapidly worsening rash. Fever with a new blistering rash also warrants clinical advice when the diagnosis is uncertain. Phone ahead so the service can protect other patients.

Ask when exposure occurred, how long to avoid close contact, whether vaccination or antiviral treatment is suitable, and what symptoms should trigger a same-day call. Share the person’s age, pregnancy status, immune history, and any contact with vulnerable people.