  Since their announcement in November 2020, COVID-19 vaccines were largely
debated by the press and social media. With most studies focusing on COVID-19
disinformation in social media, little attention has been paid to how
mainstream news outlets framed COVID-19 narratives compared to alternative
sources. To fill this gap, we use cognitive network science and natural
language processing to reconstruct time-evolving semantic and emotional frames
of 5745 Italian news, that were massively re-shared on Facebook and Twitter,
about COVID-19 vaccines. We found consistently high levels of
trust/anticipation and less disgust in the way mainstream sources framed the
general idea of "vaccine/vaccino". These emotions were crucially missing in the
ways alternative sources framed COVID-19 vaccines. More differences were found
within specific instances of vaccines. Alternative news included titles framing
the AstraZeneca vaccine with strong levels of sadness, absent in mainstream
titles. Mainstream news initially framed "Pfizer" along more negative
associations with side effects than "AstraZeneca". With the temporary
suspension of the latter, on March 15th 2021, we identified a
semantic/emotional shift: Even mainstream article titles framed "AstraZeneca"
as semantically richer in negative associations with side effects, while
"Pfizer" underwent a positive shift in valence, mostly related to its higher
efficacy. "Thrombosis" entered the frame of vaccines together with fearful
conceptual associations, while "death" underwent an emotional shift, steering
towards fear in alternative titles and losing its hopeful connotation in
mainstream titles. Our findings expose crucial aspects of the emotional
narratives around COVID-19 vaccines adopted by the press, highlighting the need
to understand how alternative and mainstream media report vaccination news.
