I would expect to see conflicting narratives in any country with free press. Why would we expect different outlets with different biases to run consistent narratives?
The only way to create a true counter weight is the amount of time encompassing the false hood should be the same amount of time given to the retraction. 1 day of false hood should equal 1 day of retraction.
Will this mode of operation exist, most likely not. The closest the USA had to such would be the Fairness Doctrine. [0]
The NYT intentionally runs stories that are highly dubious or they know to be false, then later issue a small retraction in a footnote.
The latest fake news they published was the story around Zohran Mamdani where they used hacked data from Colombia University to claim he checked "black" on the admission documents to gain an unfair advantage. That's because they are partisan hacks. I don't necessarily like Zohran, but he represented a threat to mainstream Democrats therefore the NYT had to do something about him.
I saw a similar theme in right-wing American propaganda wherein American conservatives know that their media is biased, but they assume that "mainstream media" is just as bad.
It seems like in all of these cases, propagandists aren't trying to get people to believe the propaganda, but rather to discredit the entire idea of objective facts or reliable reporting.
If some media comes disagreeing, they are blatantly lying. Also, there should not be diverging narratives about whether if you jump off a cliff, you will fall.
The effect is so strong and universal that everybody finds it.
Okay, if there is any such thing as objective truth then this (by which i mean your statement that there should not be conflicting narratives, not the statement about the vaccine itself) is objectively false.
The COVID vaccines were pressed into widespread public distribution on an emergency use authorization; any other newly-developed vaccine would have spent years mired in clinical trials and debate. The first COVID vaccines deployed would have taken even longer because they were also the first mRNA vaccines. There was not by any means a consensus that they were safe or effective, only that the risk was justifiable in light of a sudden global health crises.
And also have a diversified professional media, so that the money leaves a track.
Edit after down votes: The paragraph above was meant on why would one expect conflicting narratives not from different sources, as the Parent Comment stated, but rather from supposedly official sources or propaganda outlets. My bad, must have read the comment on a hurry.