Sounds absurd, right? Some crazy anti-vax thing - surely...

Washington Post: Johnson & Johnson vaccine was contaminated by ingredients from another company’s vaccine at a manufacturing plant in Baltimore, federal officials confirmed Wednesday

NYT: Workers .. accidentally conflated the ingredients several weeks ago, contaminating up to 15 million doses of Johnson & Johnson’s vaccine and forcing regulators to delay authorization of the plant’s production lines.

The plant is run by Emergent BioSolutions, a manufacturing partner to both Johnson & Johnson and AstraZeneca, the British-Swedish company whose vaccine has yet to be authorized for use in the United States. Federal officials attributed the mistake to human error.

Anonymous Health Official: We are going to make sure that we understand what happened. We have to work through and find out what is going on.

Not sure why Health officials need to be anonymous - The WP says he/she was "not authorized to discuss the situation". Seems like no one was authorized to discuss it coz it happened 'several weeks ago' but no a peep.

Emergent: There are rigorous quality checks throughout our vaccine manufacturing processes, and through these checks a single batch of drug substance was identified that did not meet specifications and our rigorous quality standards. We isolated this batch and it will be disposed of properly.

Your standards can't be that rigorous - otherwise how would you come to mix up ingredients from two completely different vaccines?