Mostly against COVID spike (S) protein that facilitates host cell entry.

Pfizer vaccine is mRNA vaccine, completely in vitro derived, uses nanoparticles to aid absorption into host cells which then produce the S protein themselves from the mRNA.

AstraZeneca vaccine is chimp adenovirus vector for genetic sequence – mRNA produced once virus taken up by host cell.

From Autumn 2025, only children over 6/12 who are immunosuppressed are eligible for a COVID booster (given with flu in the autumn). The other clinical risk groups eg chronic heart/lung, DM no longer apply.

This includes:

• biologics (specifies TNF receptor biologics, IL6/17/12/23 inhibitors),
• methotrexate, azathioprine, 6MP, MMF (but not hydroxychloroquine or sulfasalazine).
• High dose steroids for more than 10 days, or moderate dose (0.5mg/kg pred) for more than 4 weeks.

Ideally the vaccine should be given at time of minimum immunosuppression, if treatment is intermittent (eg 2 weeks before/after treatment).