Table 2 Stance categories and definitions

Promotional

Videos communicate public health benefits or safety of vaccination.

Videos encourage vaccination.

Describes risks of not vaccinating

Posts refute claims that vaccines are dangerous.

Ambiguous

Content contains indecision, uncertainty on the risks or benefits of vaccination.

Contains disapproving and approving information.

Neutral

Contains no elements of uncertainty, promotional or negative content.

These are often statements.

This includes factual recommendations about vaccines.

Discouraging

Contains negative attitudes/arguments against vaccines.

Contains questions re. effectiveness/safety or possibility of adverse reactions that may or may not be proven.

Discourages the use of recommended vaccines.

Indefinite-Ironic

Has no clear identifiable stance: does not clearly promote or discourage vaccines, does not have elements of uncertainty, nor does it have a clearly neutral stance.

Has an ironic, humorous nature.

Typically refers to a challenge or a trend.