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Even if a vaccine was fast tracked through the regulatory process in an emergency effort to control a pandemic, it's still going to see some significant human testing first. It's contents and production methodology are also going to be documented and held to strict standards. Even in the case of a monumental screw up where it's contaminated with something that's not supposed to be there, the odds if it causing a fraction of the harm as what's being vaccinated against is negligible.
The potential for damage from accidental contamination is limited and the idea that vaccine supplies would or could be deliberately used to introduce something, other than the vaccine in question, is paranoia. You can't hide anything you're distributing in quantity.
It's largely a moot point in an emergency anyway. If this is a new pandemic, it will be everywhere long before a vaccine is ready in quantity. Despite what some overly optimistic media stories or hyped up stock prices may seem to imply, it takes time to develop vaccines...and then you have to convince someone with the means (meaning one of a handful of big pharma giants) that it will be profitable to mass produce...then they have to manufacture and distribute it.
Far more likely you'll want a vaccine and not be able to get it than have someone try to force it on you over your protests...unless the virus becomes endemic and you're too much of an idiot to see the benefits of modern medicine when they won't let your kids attend public school without getting a proven vaccine against a demonstrably harmful pathogen.
This is unbelievable, how the Hell does not wanting to be injected with an untested serum form China equate being an anti-vaxxer?
It doesn't, but equating any vaccine that would approved by any remotely credible health system with "an untested" anything does sound rather biased against vaccination. Anything like that would probably be illegal to sell/distribute.