{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,8,28]],"date-time":"2025-08-28T12:19:35Z","timestamp":1756383575678,"version":"3.40.5"},"reference-count":38,"publisher":"Public Library of Science (PLoS)","issue":"6","license":[{"start":{"date-parts":[[2022,6,10]],"date-time":"2022-06-10T00:00:00Z","timestamp":1654819200000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["www.plosone.org"],"crossmark-restriction":false},"short-container-title":["PLoS ONE"],"abstract":"<jats:p>As a member state of the European Union, where vaccines against COVID-19 are available and affordable, Bulgaria reports the lowest immunization coverage and the most pronounced vaccine distrust. The present study aimed to assess the self-reported adverse reactions following COVID-19 vaccination as a possible tool to increase the trust in vaccines. A cross-sectional survey-based study, covering 761 vaccinated respondents, was conducted in Plovdiv (469 with an mRNA vaccine and 292 with an adenoviral vector vaccine). Descriptive statistics parametric and non-parametric methods were applied. Statistical significance was set at p&lt;0.05. The median age of the respondents was 42 years, females (72.5%). At least one adverse reaction was reported in 89.9% of those immunized with mRNA vaccine and 93.8% in the adenoviral vector vaccine group (p&gt;0.05). They were mild to moderate and resolved within several days. The levels of local reactions were comparable: 91.7% in those who received mRNA and 89.7% in those who received an adenoviral vector vaccine (p = 0.366). The most common types of systemic reactions were fatigue, headache, and muscle pains. An association was found between the systemic reactions and the type of vaccine administered: 59.7% in mRNA recipients and 89.4% in adenoviral vector vaccinees (p&lt;0.001). None of the registered systemic reactions required medical attention. There were 3 reports of generalized urticaria after an mRNA and 2 after an adenoviral vector vaccine. The reported reactions are relatively high but expected and no adverse events have been reported that are not listed in the official Summary of Product Characteristics.<\/jats:p>","DOI":"10.1371\/journal.pone.0269727","type":"journal-article","created":{"date-parts":[[2022,6,10]],"date-time":"2022-06-10T17:39:32Z","timestamp":1654882772000},"page":"e0269727","update-policy":"https:\/\/doi.org\/10.1371\/journal.pone.corrections_policy","source":"Crossref","is-referenced-by-count":6,"title":["Reporting adverse events of COVID-19 vaccines: The case of Bulgaria"],"prefix":"10.1371","volume":"17","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-9270-5996","authenticated-orcid":true,"given":"Vanya","family":"Rangelova","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6417-5681","authenticated-orcid":true,"given":"Ralitsa","family":"Raycheva","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Sara","family":"Sariyan","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ani","family":"Kevorkyan","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"340","published-online":{"date-parts":[[2022,6,10]]},"reference":[{"issue":"55","key":"pone.0269727.ref001","first-page":"105924","article-title":"Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and corona virus disease-2019 (COVID-19): the epidemic and the challenges","volume":"17","author":"CC Lai","year":"2020","journal-title":"International journal of antimicrobial agents"},{"issue":"2","key":"pone.0269727.ref002","doi-asserted-by":"crossref","first-page":"226","DOI":"10.1016\/j.vaccine.2018.11.056","article-title":"Cost-effectiveness of adult vaccinations: A systematic review","volume":"37","author":"AJ Leidner","year":"2019","journal-title":"Vaccine"},{"key":"pone.0269727.ref003","article-title":"Attitudes toward a potential SARS-CoV-2 vaccine: A survey of U.S. adults","author":"K. 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Available from: https:\/\/www.ecdc.europa.eu\/sites\/default\/files\/documents\/COVID-19-vaccination-strategies-and-deployment-plans-Nov-2021.pdf"},{"issue":"4","key":"pone.0269727.ref006","first-page":"17","article-title":"Vaccine hesitancy: key elements and Bulgaria\u2019s place on the global map","volume":"57","author":"S Stoitsova","year":"2021","journal-title":"Medical review"},{"key":"pone.0269727.ref007","doi-asserted-by":"crossref","first-page":"n2412","DOI":"10.1136\/bmj.n2412","article-title":"Covid-19: Why the Balkans\u2019 vaccine rollout lags behind most of Europe","volume":"375","author":"H Boytchev","year":"2021","journal-title":"BMJ"},{"key":"pone.0269727.ref008","unstructured":"European center for disease prevention and control (2021). Covid-19 country overviews (week 49, 2021). Available from: https:\/\/covid19-country-overviews.ecdc.europa.eu\/"},{"issue":"7","key":"pone.0269727.ref009","doi-asserted-by":"crossref","first-page":"922","DOI":"10.1016\/S1473-3099(21)00344-3","article-title":"Global COVID-19 vaccine inequity","volume":"21","author":"T Burki","year":"2021","journal-title":"The Lancet. Infectious diseases"},{"journal-title":"Report of the SAGE Working Group on Vaccine Hesitancy","year":"2014","author":"World Health Organization","key":"pone.0269727.ref010"},{"key":"pone.0269727.ref011","unstructured":"C The Organisation for Economic Co-operation and Development, OECD Policy Responses to Coronavirus (COVID-19) (2021). Enhancing public trust in COVID-19 vaccination: The role of governments. Available from: https:\/\/read.oecd-ilibrary.org\/view\/?ref=1094_1094290-a0n03doefx&title=Enhancing-public-trust-in-COVID-19-vaccination-The-role-of-governments"},{"key":"pone.0269727.ref012","doi-asserted-by":"crossref","first-page":"1149","DOI":"10.3758\/BRM.41.4.1149","article-title":"Statistical power analyses using G*Power 3.1: Tests for correlation and regression analyses","volume":"41","author":"F. Faul","year":"2009","journal-title":"Behavior Research Methods"},{"key":"pone.0269727.ref013","doi-asserted-by":"crossref","first-page":"1428","DOI":"10.3390\/jcm10071428","article-title":"Prevalence of COVID-19 Vaccine Side Effects among Healthcare Workers in the Czech Republic","volume":"10","author":"A. Riad","year":"2021","journal-title":"J. Clin. Med"},{"issue":"8","key":"pone.0269727.ref014","doi-asserted-by":"crossref","first-page":"752","DOI":"10.3390\/biology10080752","article-title":"Side Effects of mRNA-Based and Viral Vector-Based COVID-19 Vaccines among German Healthcare Workers","volume":"10","author":"M. Klugar","year":"2021","journal-title":"Biology"},{"key":"pone.0269727.ref015","doi-asserted-by":"crossref","first-page":"673","DOI":"10.3390\/vaccines9060673","article-title":"Safety of ChAdOx1 nCoV-19 Vaccine: Independent Evidence from Two EU States","volume":"9","author":"A. Riad","year":"2021","journal-title":"Vaccines"},{"key":"pone.0269727.ref016","volume-title":"Epidemiology and Prevention of Vaccine-Preventable Diseases","author":"Centers for Disease Control and Prevention","year":"2021","edition":"14"},{"issue":"20","key":"pone.0269727.ref017","doi-asserted-by":"crossref","first-page":"2191","DOI":"10.1001\/jama.2013.281053","article-title":"World Medical Association Declaration of Helsinki: ethical principles for medical research involving human subjects","volume":"310","author":"World Medical Association","year":"2013","journal-title":"JAMA"},{"volume-title":"Priorities for the National Vaccine Plan.","year":"2010","author":"Institute of Medicine","key":"pone.0269727.ref018"},{"article-title":"Population by districts, municipalities, place of residence and sex.","year":"2021","author":"National Statistical Institute (NSI)","key":"pone.0269727.ref019"},{"key":"pone.0269727.ref020","doi-asserted-by":"crossref","first-page":"760047","DOI":"10.3389\/fmed.2021.760047","article-title":"BNT162b2 and ChAdOx1 SARS-CoV-2 Post-vaccination Side-Effects Among Saudi Vaccinees","volume":"8","author":"AN Alghamdi","year":"2021","journal-title":"Front. 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Available from: https:\/\/www.cdc.gov\/vaccines\/covid-19\/info-by-product\/pfizer\/reactogenicity.html"},{"key":"pone.0269727.ref025","doi-asserted-by":"crossref","DOI":"10.1136\/jclinpath-2021-207572","article-title":"Antibody response and self-reported adverse reactions following vaccination with Comirnaty: a pilot study from a Croatian university hospital","author":"I Lapi\u0107","year":"2021"},{"key":"pone.0269727.ref026","article-title":"Serious adverse events reported from the COVID-19 vaccines: A descriptive study based on WHO database","author":"S Dutta","year":"2021","journal-title":"medRxiv"},{"issue":"8","key":"pone.0269727.ref027","first-page":"e17055","article-title":"Reporting at Least One Adverse Effect Post-COVID-19 Vaccination from Primary Health Care in Muscat","volume":"13","author":"TS Al Ghafri","year":"2021","journal-title":"Cureus"},{"key":"pone.0269727.ref028","doi-asserted-by":"crossref","first-page":"1979","DOI":"10.1016\/S0140-6736(20)32466-1","article-title":"Safety and immunogenicity of ChAdOx1nCoV-19 vaccine administered in a prime-boost regimen in young and old adults (COV002): a single-blind, randomised, controlled, phase 2\/3 trial","volume":"396","author":"MN Ramasamy","year":"2020","journal-title":"Lancet"},{"key":"pone.0269727.ref029","doi-asserted-by":"crossref","first-page":"376","DOI":"10.1016\/j.ijid.2021.04.047","article-title":"Side effects of BNT162b2 mRNA COVID-19 vaccine: a randomized, cross-sectional study with detailed self-reported symptoms from healthcare workers","volume":"106","author":"RAK Kadali","year":"2021","journal-title":"Int J Infect Dis"},{"key":"pone.0269727.ref030","doi-asserted-by":"crossref","first-page":"939","DOI":"10.1016\/S1473-3099(21)00224-3","article-title":"Vaccine side-effects and SARS-CoV-2 infection after vaccination in users of the COVID Symptom Study app in the UK: a prospective observational study","volume":"21","author":"C Menni","year":"2021","journal-title":"Lancet Infect Dis."},{"key":"pone.0269727.ref031","doi-asserted-by":"crossref","first-page":"1389","DOI":"10.2147\/IJGM.S310497","article-title":"Minor to moderate side effects of Pfizer-BioNTech COVID-19 vaccine among Saudi residents: a retrospective cross-sectional study","volume":"14","author":"NA El-Shitany","year":"2021","journal-title":"Int J Gen Med"},{"key":"pone.0269727.ref032","unstructured":"Gallup (2018). Wellcome Global Monitor. How does the world feel about science and health? Available from: file:\/\/\/C:\/Users\/PCUser\/AppData\/Local\/Temp\/wellcome-global-monitor-2018.pdf"},{"key":"pone.0269727.ref033","unstructured":"Standard Eurobarometer 95 Spring 2021. Public opinion in the European Union, Available from: http:\/\/www.pensamientocritico.org\/wp-content\/uploads\/2021\/10\/Eurobarometro-Primavera-2021_compressed.pdf"},{"issue":"9","key":"pone.0269727.ref034","doi-asserted-by":"crossref","first-page":"1168","DOI":"10.1016\/j.vaccine.2019.01.033","article-title":"Measuring vaccine hesitancy, confidence, trust and flu vaccine uptake: results of a national survey of white and African American adults","volume":"37","author":"SC Quinn","year":"2019","journal-title":"Vaccine"},{"issue":"45","key":"pone.0269727.ref035","doi-asserted-by":"crossref","first-page":"6059","DOI":"10.1016\/j.vaccine.2017.09.046","article-title":"A systematic review of factors affecting vaccine uptake in young children","volume":"35","author":"LE Smith","year":"2017","journal-title":"Vaccine"},{"key":"pone.0269727.ref036","doi-asserted-by":"crossref","DOI":"10.2139\/ssrn.3593098","article-title":"Hesitancy towards a COVID-19 vaccine and prospects for herd immunity","author":"L Thunstrom","year":"2020"},{"issue":"4","key":"pone.0269727.ref037","doi-asserted-by":"crossref","first-page":"325","DOI":"10.1007\/s10654-020-00634-3","article-title":"Vaccine confidence in the time of COVID-19","volume":"35","author":"EA Harrison","year":"2020","journal-title":"Eur J Epidemiol"},{"issue":"4","key":"pone.0269727.ref038","doi-asserted-by":"crossref","first-page":"479","DOI":"10.1177\/0272989X15607855","article-title":"Unknown risks: parental hesitation about vaccination","volume":"36","author":"LL Blaisdell","year":"2016","journal-title":"Med Decis Mak"}],"container-title":["PLOS ONE"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/dx.plos.org\/10.1371\/journal.pone.0269727","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2022,6,10]],"date-time":"2022-06-10T17:40:08Z","timestamp":1654882808000},"score":1,"resource":{"primary":{"URL":"https:\/\/dx.plos.org\/10.1371\/journal.pone.0269727"}},"subtitle":[],"editor":[{"given":"Mohd","family":"Adnan","sequence":"first","affiliation":[],"role":[{"role":"editor","vocabulary":"crossref"}]}],"short-title":[],"issued":{"date-parts":[[2022,6,10]]},"references-count":38,"journal-issue":{"issue":"6","published-online":{"date-parts":[[2022,6,10]]}},"URL":"https:\/\/doi.org\/10.1371\/journal.pone.0269727","relation":{},"ISSN":["1932-6203"],"issn-type":[{"type":"electronic","value":"1932-6203"}],"subject":[],"published":{"date-parts":[[2022,6,10]]}}}