I've personally found saying "I don't think there's evidence of that" to be one of the more powerful phrases out there.

The Pfizer contract is commercially sensitive. You won't be able to see it. Nor will anyone else. It's likely from the slow delivery that New Zealand is not paying a particularly high price per dose. Any shady promises to Pfizer within the contract still must comply with New Zealand law, so there's not much room for anything outlandish. Given a contract is just a legally enforceable agreement, there's no point putting illegal clauses in it, unless you believe there is mystical powers when signing documents in blood.

Many people die after receiving the Covid vaccine. Some have heart attacks. Some have brain hemorrhages. Some get dismembered in car crashes. Dying after receiving a vaccine is not the same as dying from the vaccine. Lots of people get that wrong. International data shows that people getting vaccinated aren't dying at higher rates than people not getting vaccinated. Potential fatal side-effects of Covid vaccines are barely quantifiable. Potentially fatal side-effects of Covid are quantifiable and common.