Evidence map›Paper›PMID 33430428›Full record

ArticleVaccines2021

Vaccine Hesitancy on Social Media: Sentiment Analysis from June 2011 to April 2019.

Hilary Piedrahita-Valdés, Diego Piedrahita-Castillo, Javier Bermejo-Higuera, Patricia Guillem-Saiz, Juan Ramón Bermejo-Higuera, Javier Guillem-Saiz, Juan Antonio Sicilia-Montalvo, Francisco Machío-Regidor

Abstract read
In one paragraph

Article in Vaccines, 2021. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 61 papers, 1 of them a synthesis that pooled it.

0numbers the graph read from it
0cells of the map it votes in
61citing papers in PubMed, 1 pooled it
–field-weighted citation impact
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

61 citing papers in PubMed, 1 synthesis or guideline pooled it.

  1. Pooled it
  2. Article
  3. Article
  4. Social Perception, Trust, and Reluctance Towards Vaccines: A Bibliometric Analysis (2019-2025).International journal of environmental research and public health · 2026
    Review
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  6. Twitter reveals spatio-temporal variation in vaccine concerns in Sub-Saharan Africa.medRxiv : the preprint server for health sciences · 2025
    Article
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1 more citing papers are in PubMed but not listed here.

4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

8 authors.

Hilary Piedrahita-ValdésDepartment of Preventive Medicine and Public Health, Bromatology, Toxicology and Legal Medicine, University of Valencia, 46010 Valencia, Spain.
Diego Piedrahita-CastilloFaculty of Engineering and Technology, International University of La Rioja, 26006 Logroño, Spain.ORCID 0000-0001-9252-1994
Javier Bermejo-HigueraFaculty of Engineering and Technology, International University of La Rioja, 26006 Logroño, Spain.ORCID 0000-0003-3681-2572
Patricia Guillem-SaizDepartment of Preventive Dentistry, Epidemiology and Public Health, European University of Valencia, 46010 Valencia, Spain.
Juan Ramón Bermejo-HigueraFaculty of Engineering and Technology, International University of La Rioja, 26006 Logroño, Spain.ORCID 0000-0002-0197-8663
Javier Guillem-SaizDepartment of Psychology, International University of Valencia, 46002 Valencia, Spain.ORCID 0000-0002-5438-9715
Juan Antonio Sicilia-MontalvoFaculty of Engineering and Technology, International University of La Rioja, 26006 Logroño, Spain.ORCID 0000-0002-5962-4147
Francisco Machío-RegidorFaculty of Engineering and Technology, International University of La Rioja, 26006 Logroño, Spain.

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

Vaccine hesitancy was one of the ten major threats to global health in 2019, according to the World Health Organisation. Nowadays, social media has an important role in the spread of information, misinformation, and disinformation about vaccines. Monitoring vaccine-related conversations on social media could help us to identify the factors that contribute to vaccine confidence in each historical period and geographical area. We used a hybrid approach to perform an opinion-mining analysis on 1,499,227 vaccine-related tweets published on Twitter from 1st June 2011 to 30th April 2019. Our algorithm classified 69.36% of the tweets as neutral, 21.78% as positive, and 8.86% as negative. The percentage of neutral tweets showed a decreasing tendency, while the proportion of positive and negative tweets increased over time. Peaks in positive tweets were observed every April. The proportion of positive tweets was significantly higher in the middle of the week and decreased during weekends. Negative tweets followed the opposite pattern. Among users with ≥2 tweets, 91.83% had a homogeneous polarised discourse. Positive tweets were more prevalent in Switzerland (71.43%). Negative tweets were most common in the Netherlands (15.53%), Canada (11.32%), Japan (10.74%), and the United States (10.49%). Opinion mining is potentially useful to monitor online vaccine-related concerns and adapt vaccine promotion strategies accordingly.

Indexed as

content analysismachine learningopinion miningsentiment analysissocial mediaTwittervaccinationvaccine hesitancy

Identifiers

PMID33430428
PMCPMC7827575

What OpenQuestion holds

Textmetadata
LicenceCC BY
Read underepoch 390

Registered trials

None linked

Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.