CS000000-A | 06/29/21

Rapid COVID-19 State of Vaccine 

Confidence Insights Report

June 8 – 24, 2021 | Cases of Myocarditis and Pericarditis following 

mRNA COVID-19 Vaccination 

Vaccine Confidence and Demand Team, Insights Unit

Following the Advisory Committee on Immunization Practices’ (ACIP) 

meeting on June 23, 2021 about myocarditis and pericarditis following mRNA 

COVID-19 vaccination, a special insights report was conducted using the same 

methods and inputs from the COVID-19 State of Vaccine Confidence Insights Reports.

This report seeks to better understand the perceptions and sentiment of 

consumers. The report details threats to COVID-19 vaccine confidence, content gaps 

and information voids, circulating mis- and disinformation, and action steps to take.

The information in this report is a snapshot from June 8, 2021, through June 24, 2021.  

Contents

2 Background

3 Perceptions, Concerns, and Threats to Vaccine 

Confidence

4 Content Gaps and Information Voids

5 Misinformation and Disinformation Themes

6 Ways to Take Action

8 Appendix

Centers for Disease Control & Prevention, 

COVID-19 Response, Vaccine Task Force

Vaccine Confidence & Demand Team, Insights Unit

The findings and conclusions in this report are those of the author(s) and do not necessarily represent the official position of the Centers for Disease Control and Prevention (CDC).
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Rapid COVID-19 State of Vaccine Confidence Insights Report

June 8 – 24, 2021 | Cases of Myocarditis and Pericarditis following mRNA COVID-19 Vaccination

Background

Concerns about myocarditis following vaccination entered the public conversation in late May 2021 following reported 

cases among adolescents. These cases emerged in the news soon after the Emergency Use Authorization (EUA) for the 

Pfizer-BioNTech COVID-19 Vaccine was expanded to include adolescents aged 12 through 15 years old,1,2 which had been 

authorized for people 16 years and older since December 11, 2020. Initial reactions and information gaps were reviewed 

in the Special COVID-19 State of Vaccine Confidence Insights Reports on Adolescent Vaccination. Over the following 

five weeks, mentions of myocarditis and COVID-19 vaccines on digital media increased by 204% as a result of coverage 

by national and local news outlets,3,4 mis- and disinformation blogs,5,6 and social media chatter. Many of the circulating 

stories focused on adolescents and young adults being hospitalized or reportedly dying from myocarditis following 

vaccination.7,8,9,10,11,12,13 Views of Centers for Disease Control and Prevention’s (CDC) webpage on myocarditis and pericarditis

following vaccination with an mRNA COVID-19 vaccine grew by over 160% between June 10, 2021, and June 16, 2021 

compared to the week prior. At the same time, external web searches related to vaccination and myocarditis also rose.

0

5000

10000

15000

20000

25000

30000

35000

May 23:

CDC investigating 

myocarditis following 

vaccination in 

adolescents and 

young adults. 

June 23:

Emergency ACIP 

meeting held.

June 2:

Study from Israel finds 

possible link between 

Pfizer-BioNTech’s 

COVID-19 Vaccine and 

myocarditis.

June 10:

Emergency ACIP 

meeting 

announced.

0

5000

10000

15000

20000

25000

30000

35000

40000

Mentions of Myocarditis & COVID-19 Vaccines on Digital Media

May 18, 2021 - June 24, 2021

Report Date Range:

June 8 -24,2021

Source: Meltwater

June 21:

WHO updates guidance 

indicating children 

should not be 

prioritized for COVID-19 

vaccination.
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Rapid COVID-19 State of Vaccine Confidence Insights Report

June 8 – 24, 2021 | Cases of Myocarditis and Pericarditis following mRNA COVID-19 Vaccination

Perceptions, Concerns, and Threats to Vaccine Confidence 

Some news outlets and members of the public criticized CDC and the Advisory Committee on Immunization 

Practices (ACIP) for waiting to schedule an emergency meeting to discuss the potential connection between 

myocarditis and COVID-19 vaccination, only to delay it by five days due to a new federal holiday.14,15,16,17,18 Some 

consumers felt this perceived lack of urgency around the meeting was because the U.S. government is prioritizing 

reaching President Biden’s vaccination coverage goal over safety.19

Some consumers hoped ACIP’s meeting would help them make an 

informed decision regarding getting themselves or their adolescent 

vaccinated and to better understand the risk of myocarditis, severity 

of the cases reported, and the potential long term side effects.20,21,22,23

However, following the meeting, many consumers expressed frustration 

indicating that the meeting did not provide the answers they were 

seeking.24,25,26 Some consumers had hoped ACIP would provide guidance 

on either delaying or omitting the second dose to mitigate potential harm 

as many cases of myocarditis and pericarditis seemed to emerge following 

the second dose of vaccine.27,28,29 A few consumers even reported that 

they had already decided to delay their or their child’s second dose.30

Other consumers felt the committee should have paused the use of mRNA 

vaccines generally or at least for young people under 30 years old until 

more is known about the incidence and risk of myocarditis following 

vaccination. 31,32,33 Some cited the recommendation to pause Johnson & 

Johnson’s Janssen COVID-19 Vaccine after only six cases of thrombosis 

with thrombocytopenia syndrome (TTS) as justification.34,35,36 Some 

consumers noted that myocarditis or pericarditis following vaccination 

was not an issue for young people alone, despite the focus of the meeting 

and news coverage, as people in all age groups reported having had or knowing someone who had experienced 

a heart-related event following vaccination.37,38,39 Some healthcare providers expressed a desire for updated 

recommendations to mitigate the potential for adverse events following vaccination for different age groups and 

demographics.40,41

Despite reassurance from health authorities 

following the meeting that vaccination was safe and 

effective, and that cases of myocarditis following 

vaccination were rare and most were mild,42,43,44,45

consumer opinions diverged. Some parents and 

other consumers continued to express that they felt 

the risk for myocarditis and other adverse events 

for people under 30 years old far outweighed the 

benefits.46,47,48,49 Many also felt that no case of myocarditis is truly mild and expressed concerns about the potential 

long-term and permanent side effects.50,51,52 Additionally, some consumers expressed the belief that cases were being 

underreported, with some even claiming that this was made worse by healthcare professionals claiming heart-related 

symptoms were unrelated to vaccination.53,54,55,56 Some felt their opinions and concerns were validated when the World 

Health Organization’s guidance for vaccination was updated to clarify that children and adolescents who are not at 

high risk for severe COVID-19 illness should not be prioritized for vaccination at this time.57,58,59 At the same time, other 

consumers felt that the risk of severe illness and complications, particularly myocarditis, from COVID-19 was greater than 

the risk of an adverse event from vaccination.60,61,62 They also noted that vaccinating people under 30 years old against 

COVID-19 is important for the United States to reach population immunity.63,64
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Rapid COVID-19 State of Vaccine Confidence Insights Report

June 8 – 24, 2021 | Cases of Myocarditis and Pericarditis following mRNA COVID-19 Vaccination

Content Gaps and Information Voids

Content gaps and information voids emerged around myocarditis following COVID-19 vaccination in late May 2021. Initial 

content gaps and information voids from May, many of which still exist, can be reviewed in the Special COVID-19 State 

of Vaccine Confidence Insights Reports on Adolescent Vaccination. Questions from consumers emerged organically on 

social media and forum platforms in response to news coverage and federal government social media channels, as well as 

through inquires to CDC-INFO. The following lists the most frequently asked questions by theme:

Questions about myocarditis and pericarditis

 What are myocarditis and pericarditis? Is one more severe and how is severity determined?

 What are the symptoms of myocarditis or pericarditis?

 What are the long-term effects of myocarditis or pericarditis? Can they cause permanent heart damage?

Questions about incidence rates and data

 What is the background rate of myocarditis among people under 30 years old?

 What is the rate of myocarditis following vaccination for people 30 years and older?

 What is the rate of myocarditis among people who have COVID-19? 

 Are people more likely to get myocarditis because of COVID-19 or because of vaccination?

 Has anyone died of myocarditis or pericarditis following vaccination?

 Has myocarditis or pericarditis been observed in clinical trials for other COVID-19 vaccines?

 Why is a pause not recommended given that J&J/Janssen vaccine paused after six cases of TTS?

Questions about risk

 If I previously had COVID-19, am I at increased risk for developing myocarditis or pericarditis after vaccination?

 How is the risk-benefit of vaccination being determined given the low incidence rate of COVID-19 in people under

30 years old?

 What ages are at risk for myocarditis following vaccination?

 Are pregnant women at increased risk for developing myocarditis after vaccination?

Questions about vaccine safety

 If I have had myocarditis or another heart-related condition, is it safe to be vaccinated?

 If I have experienced myocarditis or similar side effects after my first dose, should I still get a second dose?

Questions about vaccine administration

 Would lengthening the time between the first and second dose of vaccine reduce the occurrence of myocarditis?

 How long can you wait between the first and second dose of mRNA vaccines?

 Should adolescents or young adults only receive one dose of vaccine?

 Could lower doses of vaccine reduce the occurrence of myocarditis?

 If I received an mRNA vaccine for my first dose and feel unsafe taking the second dose, can I get a dose of J&J/Janssen

vaccine?

 When will COVID-19 vaccines not using mRNA technology be available to adolescents?

Other questions

 How are mRNA vaccines causing myocarditis? Is it related to the spike protein?

 Why is this affecting males more than females?
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Rapid COVID-19 State of Vaccine Confidence Insights Report

June 8 – 24, 2021 | Cases of Myocarditis and Pericarditis following mRNA COVID-19 Vaccination

Misinformation and Disinformation Themes 

With the existence of several information gaps regarding myocarditis and COVID-19 vaccines, mis- and disinformation 

spread online broadly. Some vocal vaccine deniers felt their beliefs that COVID-19 vaccines are unsafe were validated and 

fueled by a lack of consistent messaging and perceived lack of transparency from federal agencies.65,66,67 Below are the 

most central mis- and disinformation themes related to myocarditis following COVID-19 vaccination: 

Myocarditis after vaccination is not rare and hospitals and healthcare professionals do not know how to report adverse 

events. Mis- and disinformation outlets promoted stories claiming that hospital personnel were ‘clueless’ about reporting 

adverse events following vaccination to the Vaccine Adverse Event Reporting System (VAERS),68 intensifying concerns that 

myocarditis cases are largely unreported.69,70 At the same time, some consumers have claimed that v-safe is a mechanism 

for CDC to hide adverse events because, unlike reports to VAERS, reports to v-safe are not publicly available.71

WHO said that it is not safe for kids to be vaccinated. WHO’s updated guidance that children and adolescents who are not 

at risk for severe COVID-19 should not be prioritized for vaccination at this time was misrepresented by vocal vaccine 

deniers who claimed the agency said they did not recommend vaccination for children and adolescents.72,73,74 While this 

claim has been fact checked as false,75 it was a common comment on social media promoted by those who do not plan to 

vaccinate their children or believe that benefits of vaccination outweigh the risks of COVID-19.

Pharmaceutical profits are prioritized over the safety of COVID-19 vaccines. Claims made by a former pharmaceutical vice 

president recirculated76,77 alongside an interview by an inventor of mRNA vaccine technology claiming that the vaccines 

are not safe and that companies knew that side effects like myocarditis would occur.78 This furthered long-held beliefs79

for some that CDC, along with pharmaceutical companies, has a financial interest in keeping mRNA vaccines available.80

An athlete’s collapse on the field was from myocarditis caused by vaccination.Despite this claim being fact checked 

as false,81 rumors circulated that that the collapse of a professional soccer player on the field was caused by recent 

vaccination.82,83 This connected to previous concerns expressed by parents about adolescent athletes being at increased 

risk for myocarditis following vaccination due to their physical activity levels.84
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Rapid COVID-19 State of Vaccine Confidence Insights Report

June 8 – 24, 2021 | Cases of Myocarditis and Pericarditis following mRNA COVID-19 Vaccination

Ways to Take Action

Fill content gaps and information voids. 

 Create clear, consistent messaging about vaccine developments and communicate often about what is known and unknown 

about myocarditis and pericarditis after vaccination. 

 Expand web content related to cases of myocarditis and pericarditis following COVID-19 vaccination to include information 

about signs and symptoms and when to seek medical care and better explain what myocarditis and pericarditis are, how 

serious they are, and what is known about who might be at increased risk for experiencing these adverse events. 

 Leverage available safety data to expand frequently asked questions content about myocarditis and pericarditis following 

vaccination, especially addressing concerns related to the incidence rate of myocarditis and pericarditis, comparing the risk 

to myocarditis as a complication of COVID-19. From this content, develop and disseminate messages specifically designed for 

social media platforms.

 Develop content in a variety of styles, including easy to use graphics, videos, and social media content, to answer questions 

and fill information gaps.

Disseminate messages focused on the importance of vaccination as an important tool to 

end the pandemic and the continued focus on vaccine safety. 

 Disseminate messages that the integrity and transparency of safety monitoring systems will be maintained. Increased reports 

of adverse events to safety monitoring systems are expected and will be appropriately investigated. 

 Disseminate messages that the U.S. vaccination system will continue to offer safe and effective vaccines to all consumers and 

will continue to monitor vaccine safety through rigorous vaccine safety monitoring systems. 

 Disseminate messages on agency channels highlighting that vaccination will play a key role in ending the COVID-19 

pandemic.

 Disseminate messages about how ACIP makes decisions and their role in safety monitoring and the U.S. vaccination system.

 Coordinate messages across all federal agencies to ensure alignment and credibility.

 Leverage #SleeveUp and #WeCanDoThis for consumers to highlight their continued confidence in COVID-19 vaccines and the 

vaccination system. 

 Work with partners to identify trusted messengers and local influencers to amplify vaccination stories. 

Partner with healthcare professionals.

 Provide guidance about how to communicate with patients and parents who are worried about or experiencing myocarditis 

or pericarditis following vaccination. 

 Develop materials and tools for healthcare professionals to share with their patients and parents about the benefits of 

COVID-19 vaccines, specifically addressing concerns that the risks of an adverse event outweigh the benefit of vaccination 

and perceived low risk of getting COVID-19.

 Strengthen the capacity of pediatricians, family practitioners, and healthcare professionals to have proactive vaccine 

conversations with adolescents and their parents—with special attention to those families who might have differing opinions 

about the benefits of vaccination

 Partner with healthcare professionals to better understand perceptions and opinions about COVID-19 vaccinations for 

adolescents, particularly if providers are hesitant to administer COVID-19 vaccines or discuss the benefits of vaccines with 

families. 

Address mis- and disinformation. 

 Continue to disseminate messages about VAERS, specifically how the system works, how adverse events are investigated, and 

how it is different than v-safe.

 Develop and disseminate plain language talking points and suggested social media messages and unbranded assets for social 

media influencers and the COVID-19 Community Corps. 

 Partner with technology companies and notify them of key misinformation to flag or remove. Ensure technology companies 

promote resources with credible, evidence-based information about COVID-19 vaccines beyond resources from federal agencies 

and health departments. 

 Expand Myths and Facts web content to address new mis- and disinformation themes. 

 Empower consumers to have effective, empathetic conversations about vaccines with family and friends online and offline.
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Rapid COVID-19 State of Vaccine Confidence Insights Report

June 8 – 24, 2021 | Cases of Myocarditis and Pericarditis following mRNA COVID-19 Vaccination

Ways to Take Action (cont.)

Support research efforts to better understand how overwhelming digital media coverage 

of adverse events affects vaccination intent and motivation.

 Expand current polling mechanisms to include questions about myocarditis and pericarditis following vaccination and the 

effects of the COVID-19 infodemic and cognitive overload, when there is too much information available for one to process, 

on their vaccination intent and motivation. 

 Identify poll indicators that could be used to better understand how current safety concerns impact people’s intent to get 

vaccinated.

 Expand evaluation efforts to better understand the concerns and opinions of people under 30 years old about myocarditis, 

pericarditis, and other adverse events following vaccination and how reporting of adverse events affects their intent and 

motivation to get vaccinated if they have not already. 
Page: 8

Rapid COVID-19 State of Vaccine Confidence Insights Report

June 8 – 24, 2021 | Cases of Myocarditis and Pericarditis following mRNA COVID-19 Vaccination

Appendix: Inputs and Sources

Type Input Cadence Sources Tactics for Utilization

Social Media 

Listening 

& Media 

Monitoring

Meltwater Daily  Facebook, Twitter, Instagram

 Blogs

News media

Online forums

 Share of voice topic analysis

 Emerging theme topics

Identify high reach/velocity topics

Crowd tangle Daily  Facebook

Instagram

 Sentiment analysis

Identify information gaps/voids

Identify mis/disinformation

OADC Channel 

Comment Analysis

Daily Native platform searches  Sentiment analysis

Identify message gaps/voids

Direct 

Reports

CDC-INFO Metrics Weekly CDC-INFO inquiry line list

 Prepared response (PR) usage 

report

Cross-compare PR usage with inquiry theme 

analysis

 Sentiment analysis

Identify information gaps/voids

Third Party 

Reports

Tanaq Social 

Listening +Media 

Monitoring Report

Weekly  Meltwater

 Sprout Social

 First Draft

Native platform searches

 Trending topics

Demographic and geographic conversation 

monitoring

First Draft 

News Vaccine 

Misinformation 

Insights Report

Monthly  Proprietary methods  Media trends analysis

 Emerging threats and data deficits

Online vaccine narratives

Project VCTR Weekly  Proprietary methods National and regional trends in negative 

attitudes toward vaccination

Conversations around Legislation

Virality Project Weekly  Proprietary methods  Mis- and disinformation trends related to 

COVID-19 vaccine