Below is the full information released by the Centers for Disease Control (CDC) regarding a study of Massachusetts infections in which 74% of the patients had been fully vaccinated, as well as four out of five patients who had to be hospitalized.
Outbreak of SARS-CoV-2 Infections, Including COVID-19 Vaccine Breakthrough Infections, Associated with Large Public Gatherings — Barnstable County, Massachusetts, July 2021
Early Release / July 30, 2021 / 70
Catherine M. Brown, DVM1; Johanna Vostok, MPH1; Hillary Johnson, MHS1; Meagan Burns, MPH1; Radhika Gharpure, DVM2; Samira Sami, DrPH2; Rebecca T. Sabo, MPH2; Noemi Hall, PhD2; Anne Foreman, PhD2; Petra L. Schubert, MPH1; Glen R. Gallagher, PhD1; Timelia Fink1; Lawrence C. Madoff, MD1; Stacey B. Gabriel, PhD3; Bronwyn MacInnis, PhD3; Daniel J. Park, PhD3; Katherine J. Siddle, PhD3; Vaira Harik, MS4; Deirdre Arvidson, MSN4; Taylor Brock-Fisher, MSc5; Molly Dunn, DVM5; Amanda Kearns5; A. Scott Laney, PhD2 (View author affiliations)View suggested citation
What is already known about this topic?
Variants of SARS-CoV-2 continue to emerge. The B.1.617.2 (Delta) variant is highly transmissible.
What is added by this report?
In July 2021, following multiple large public events in a Barnstable County, Massachusetts, town, 469 COVID-19 cases were identified among Massachusetts residents who had traveled to the town during July 3–17; 346 (74%) occurred in fully vaccinated persons. Testing identified the Delta variant in 90% of specimens from 133 patients. Cycle threshold values were similar among specimens from patients who were fully vaccinated and those who were not.
What are the implications for public health practice?
Jurisdictions might consider expanded prevention strategies, including universal masking in indoor public settings, particularly for large public gatherings that include travelers from many areas with differing levels of SARS-CoV-2 transmission.Article Metrics
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During July 2021, 469 cases of COVID-19 associated with multiple summer events and large public gatherings in a town in Barnstable County, Massachusetts, were identified among Massachusetts residents; vaccination coverage among eligible Massachusetts residents was 69%. Approximately three quarters (346; 74%) of cases occurred in fully vaccinated persons (those who had completed a 2-dose course of mRNA vaccine [Pfizer-BioNTech or Moderna] or had received a single dose of Janssen [Johnson & Johnson] vaccine ≥14 days before exposure). Genomic sequencing of specimens from 133 patients identified the B.1.617.2 (Delta) variant of SARS-CoV-2, the virus that causes COVID-19, in 119 (89%) and the Delta AY.3 sublineage in one (1%). Overall, 274 (79%) vaccinated patients with breakthrough infection were symptomatic. Among five COVID-19 patients who were hospitalized, four were fully vaccinated; no deaths were reported. Real-time reverse transcription–polymerase chain reaction (RT-PCR) cycle threshold (Ct) values in specimens from 127 vaccinated persons with breakthrough cases were similar to those from 84 persons who were unvaccinated, not fully vaccinated, or whose vaccination status was unknown (median = 22.77 and 21.54, respectively). The Delta variant of SARS-CoV-2 is highly transmissible (1); vaccination is the most important strategy to prevent severe illness and death. On July 27, CDC recommended that all persons, including those who are fully vaccinated, should wear masks in indoor public settings in areas where COVID-19 transmission is high or substantial.* Findings from this investigation suggest that even jurisdictions without substantial or high COVID-19 transmission might consider expanding prevention strategies, including masking in indoor public settings regardless of vaccination status, given the potential risk of infection during attendance at large public gatherings that include travelers from many areas with differing levels of transmission.
During July 3–17, 2021, multiple summer events and large public gatherings were held in a town in Barnstable County, Massachusetts, that attracted thousands of tourists from across the United States. Beginning July 10, the Massachusetts Department of Public Health (MA DPH) received reports of an increase in COVID-19 cases among persons who reside in or recently visited Barnstable County, including in fully vaccinated persons. Persons with COVID-19 reported attending densely packed indoor and outdoor events at venues that included bars, restaurants, guest houses, and rental homes. On July 3, MA DPH had reported a 14-day average COVID-19 incidence of zero cases per 100,000 persons per day in residents of the town in Barnstable County; by July 17, the 14-day average incidence increased to 177 cases per 100,000 persons per day in residents of the town (2).
During July 10–26, using travel history data from the state COVID-19 surveillance system, MA DPH identified a cluster of cases among Massachusetts residents. Additional cases were identified by local health jurisdictions through case investigation. COVID-19 cases were matched with the state immunization registry. A cluster-associated case was defined as receipt of a positive SARS-CoV-2 test (nucleic acid amplification or antigen) result ≤14 days after travel to or residence in the town in Barnstable County since July 3. COVID-19 vaccine breakthrough cases were those in fully vaccinated Massachusetts residents (those with documentation from the state immunization registry of completion of COVID-19 vaccination as recommended by the Advisory Committee on Immunization Practices,† ≥14 days before exposure). Specimens were submitted for whole genome sequencing§ to either the Massachusetts State Public Health Laboratory or the Broad Institute of the Massachusetts Institute of Technology and Harvard University. Ct values were obtained for 211 specimens tested using a noncommercial real-time RT-PCR panel for SARS-CoV-2 performed under Emergency Use Authorization at the Broad Institute Clinical Research Sequencing Platform. On July 15, MA DPH issued the first of two Epidemic Information Exchange notifications to identify additional cases among residents of U.S. jurisdictions outside Massachusetts associated with recent travel to the town in Barnstable County during July 2021. This activity was reviewed by CDC and was conducted consistent with applicable federal law and CDC policy.¶
By July 26, a total of 469 COVID-19 cases were identified among Massachusetts residents; dates of positive specimen collection ranged from July 6 through July 25 (Figure 1). Most cases occurred in males (85%); median age was 40 years (range = <1–76 years). Nearly one half (199; 42%) reported residence in the town in Barnstable County. Overall, 346 (74%) persons with COVID-19 reported symptoms consistent with COVID-19.** Five were hospitalized; as of July 27, no deaths were reported. One hospitalized patient (age range = 50–59 years) was not vaccinated and had multiple underlying medical conditions.†† Four additional, fully vaccinated patients§§ aged 20–70 years were also hospitalized, two of whom had underlying medical conditions. Initial genomic sequencing of specimens from 133 patients identified the Delta variant in 119 (89%) cases and the Delta AY.3 sublineage in one (1%) case; genomic sequencing was not successful for 13 (10%) specimens.
Among the 469 cases in Massachusetts residents, 346 (74%) occurred in persons who were fully vaccinated; of these, 301 (87%) were male, with a median age of 42 years. Vaccine products received by persons experiencing breakthrough infections were Pfizer-BioNTech (159; 46%), Moderna (131; 38%), and Janssen (56; 16%); among fully vaccinated persons in the Massachusetts general population, 56% had received Pfizer-BioNTech, 38% had received Moderna, and 7% had received Janssen vaccine products. Among persons with breakthrough infection, 274 (79%) reported signs or symptoms, with the most common being cough, headache, sore throat, myalgia, and fever. Among fully vaccinated symptomatic persons, the median interval from completion of ≥14 days after the final vaccine dose to symptom onset was 86 days (range = 6–178 days). Among persons with breakthrough infection, four (1.2%) were hospitalized, and no deaths were reported. Real-time RT-PCR Ct values in specimens from 127 fully vaccinated patients (median = 22.77) were similar to those among 84 patients who were unvaccinated, not fully vaccinated, or whose vaccination status was unknown (median = 21.54) (Figure 2).
Transmission mitigation measures included broadening testing recommendations for persons with travel or close contact with a cluster-associated case, irrespective of vaccination status; local recommendations for mask use in indoor settings, irrespective of vaccination status; deployment of state-funded mobile testing and vaccination units in the town in Barnstable County; and informational outreach to visitors and residents. In this tourism-focused community, the Community Tracing Collaborative¶¶ conducted outreach to hospitality workers, an international workforce requiring messaging in multiple languages.
The call from MA DPH for cases resulted in additional reports of cases among residents of 22 other states who had traveled to the town in Barnstable County during July 3–17, as well as reports of secondary transmission; further analyses are ongoing. As of July 3, estimated COVID-19 vaccination coverage among the eligible population in Massachusetts was 69% (3). Further investigations and characterization of breakthrough infections and vaccine effectiveness among this highly vaccinated population are ongoing.
The SARS-CoV-2 Delta variant is highly transmissible (1), and understanding determinants of transmission, including human behavior and vaccine effectiveness, is critical to developing prevention strategies. Multipronged prevention strategies are needed to reduce COVID-19–related morbidity and mortality (4).
The findings in this report are subject to at least four limitations. First, data from this report are insufficient to draw conclusions about the effectiveness of COVID-19 vaccines against SARS-CoV-2, including the Delta variant, during this outbreak. As population-level vaccination coverage increases, vaccinated persons are likely to represent a larger proportion of COVID-19 cases. Second, asymptomatic breakthrough infections might be underrepresented because of detection bias. Third, demographics of cases likely reflect those of attendees at the public gatherings, as events were marketed to adult male participants; further study is underway to identify other population characteristics among cases, such as additional demographic characteristics and underlying health conditions including immunocompromising conditions.*** MA DPH, CDC, and affected jurisdictions are collaborating in this response; MA DPH is conducting additional case investigations, obtaining samples for genomic sequencing, and linking case information with laboratory data and vaccination history. Finally, Ct values obtained with SARS-CoV-2 qualitative RT-PCR diagnostic tests might provide a crude correlation to the amount of virus present in a sample and can also be affected by factors other than viral load.††† Although the assay used in this investigation was not validated to provide quantitative results, there was no significant difference between the Ct values of samples collected from breakthrough cases and the other cases. This might mean that the viral load of vaccinated and unvaccinated persons infected with SARS-CoV-2 is also similar. However, microbiological studies are required to confirm these findings.
Event organizers and local health jurisdictions should continually assess the need for additional measures, including limiting capacity at gatherings or event postponement, based on current rates of COVID-19 transmission, population vaccination coverage, and other factors.§§§ On July 27, CDC released recommendations that all persons, including those who are fully vaccinated, should wear masks in indoor public settings in areas where COVID-19 transmission is high or substantial. Findings from this investigation suggest that even jurisdictions without substantial or high COVID-19 transmission might consider expanding prevention strategies, including masking in indoor public settings regardless of vaccination status, given the potential risk of infection during attendance at large public gatherings that include travelers from many areas with differing levels of transmission.
Hanna Shephard, Geena Chiumento, Nicole Medina, Juliana Jacoboski, Julie Coco, Andrew Lang, Matthew Doucette, Sandra Smole, Patricia Kludt, Natalie Morgenstern, Kevin Cranston, Ryan J. Burke, Massachusetts Department of Public Health; Sean O’Brien, Theresa Covell, Barnstable County Department of Health and the Environment; Marguerite M. Clougherty, John C. Welch, Community Tracing Collaborative; Jacob Lemieux, Christine Loreth, Stephen Schaffner, Chris Tomkins-Tinch, Lydia Krasilnikova, Pardis Sabeti, Broad Institute; Sari Sanchez, Boston Public Health Commission; Mark Anderson, Vance Brown, Ben Brumfield, Anna Llewellyn, Jessica Ricaldi, Julie Villanueva, CDC COVID-19 Response Team.
Corresponding author: Catherine Brown, email@example.com.
1Massachusetts Department of Public Health; 2CDC COVID-19 Response Team; 3Broad Institute, Cambridge, Massachusetts; 4Barnstable County Department of Health and the Environment, Massachusetts; 5Community Tracing Collaborative, Commonwealth of Massachusetts.
All authors have completed and submitted the International Committee of Medical Journal Editors form for disclosure of potential conflicts of interest. Stacey B. Gabriel reports receiving grants from CDC. Bronwyn MacInnis, Katherine Siddle, and Daniel Park report receiving grants from CDC and the National Institutes of Health. Taylor Brock-Fisher reports receiving a grant from the Community Tracing Collaborative. No other potential conflicts of interest were disclosed.
† As of May 2021, ACIP recommended that all adults aged ≥18 years receive any of the three COVID-19 vaccines available in the United States via Emergency Use Authorization from the Food and Drug Administration, including Pfizer-BioNTech, Moderna, and Janssen; persons aged ≥12 years are eligible to receive the Pfizer-BioNTech COVID-19 vaccine. Full vaccination is defined as receipt of 2 doses of the Pfizer-BioNTech or Moderna COVID-19 vaccines or 1 dose of Janssen COVID-19 vaccine ≥14 days before exposure.
§ Genomic sequencing was performed using Illumina NovaSeq using the NEB LunaScript RT ARTIC SARS-CoV-2 Kit. Novel mutations were not identified in the spike protein of the cluster-associated genomes compared with genomes collected during the same period from ongoing genomic surveillance efforts at Broad Institute. Raw and assembled genomic data are publicly available under NCBI BioProject PRJNA715749.
¶ 45 C.F.R. part 46, 21 C.F.R. part 56; 42 U.S.C. Sect.241(d); 5 U.S.C. Sect.552a; 44 U.S.C. Sect.3501 et seq.
** COVID-like symptoms were based on the Council of State and Territorial Epidemiologists surveillance case definition for COVID-19. https://ndc.services.cdc.gov/case-definitions/coronavirus-disease-2019-2020-08-05/
§§ One vaccinated, hospitalized COVID-19 patient had received the Pfizer-BioNTech vaccine and three had received the Janssen vaccine.
¶¶ The Community Tracing Collaborative is a multiorganization partnership that has supported COVID contact tracing and outbreak investigation in Massachusetts. https://www.mass.gov/info-details/learn-about-the-community-tracing-collaborativeexternal icon
*** A preliminary analysis matching cluster-associated COVID-19 cases with the state HIV case surveillance data identified 30 (6%) cases with verified HIV infection; all were virally suppressed, and none were hospitalized as a result of infection with SARS-CoV-2.
- CDC. COVID-19: SARS-CoV-2 variant classifications and definitions. Atlanta, GA: US Department of Health and Human Services, CDC; 2021. Accessed July 25, 2021. https://www.cdc.gov/coronavirus/2019-ncov/cases-updates/variant-surveillance/variant-info.html
- Massachusetts Department of Public Health. COVID-19 response reporting. Boston, MA: Massachusetts Department of Public Health; 2021. Accessed July 25, 2021. https://www.mass.gov/info-details/covid-19-response-reportingexternal icon
- Massachusetts Department of Public Health. Massachusetts COVID-19 vaccination data and updates. Boston, MA: Massachusetts Department of Public Health; 2021. Accessed July 25, 2021. https://www.mass.gov/info-details/massachusetts-covid-19-vaccination-data-and-updates#daily-covid-19-vaccine-report-external icon
- Christie A, Brooks JT, Hicks LA, Sauber-Schatz EK, Yoder JS, Honein MA. Guidance for implementing COVID-19 prevention strategies in the context of varying community transmission levels and vaccination coverage. MMWR Morb Mortal Wkly Rep 2021;70:1044–7. https://doi.org/10.15585/mmwr.mm7030e2external icon
FIGURE 1. SARS-CoV-2 infections (N = 469) associated with large public gatherings, by date of specimen collection and vaccination status* — Barnstable County, Massachusetts, July 2021
Abbreviation: MA DPH = Massachusetts Department of Public Health.
* Fully vaccinated was defined as ≥14 days after completion of state immunization registry–documented COVID-19 vaccination as recommended by the Advisory Committee on Immunization Practices.
FIGURE 2. SARS-CoV-2 real-time reverse transcription–polymerase chain reaction cycle threshold values* for specimens from patients with infections associated with large public gatherings, by vaccination status† — Barnstable County, Massachusetts, July 2021§
Abbreviations: Ct = cycle threshold; RT-PCR = reverse transcription–polymerase chain reaction.
* Specimens were analyzed using a noncommercial real-time RT-PCR panel for SARS-CoV-2 performed under Emergency Use Authorization at the Clinical Research Sequencing Platform, Broad Institute of the Massachusetts Institute of Technology and Harvard University.
† Fully vaccinated was defined as ≥14 days after completion of state immunization registry–documented COVID-19 vaccination as recommended by the Advisory Committee on Immunization Practices.
§ Whiskers represent minimum and maximum observations; top of box represents the third quartile (Q3), bottom represents the first quartile (Q1), and box height represents the interquartile range. Midline is the median; “x” is the mean.
Suggested citation for this article: Brown CM, Vostok J, Johnson H, et al. Outbreak of SARS-CoV-2 Infections, Including COVID-19 Vaccine Breakthrough Infections, Associated with Large Public Gatherings — Barnstable County, Massachusetts, July 2021. MMWR Morb Mortal Wkly Rep. ePub: 30 July 2021. DOI: http://dx.doi.org/10.15585/mmwr.mm7031e2external icon.
MMWR and Morbidity and Mortality Weekly Report are service marks of the U.S. Department of Health and Human Services.
Use of trade names and commercial sources is for identification only and does not imply endorsement by the U.S. Department of Health and Human Services.
References to non-CDC sites on the Internet are provided as a service to MMWR readers and do not constitute or imply endorsement of these organizations or their programs by CDC or the U.S. Department of Health and Human Services. CDC is not responsible for the content of pages found at these sites. URL addresses listed in MMWR were current as of the date of publication.
Do we know what percent of the positive cases were in people that had COVID already? I think that’s an interesting question to get an idea of natural immunity impact. That could be further subdivided by vaccinated and non vaccinated who had previously gotten COVID but at minimum - what percent of COVID positive cases are Re-infections.
They fail to include in this study it was NOT just casual contact with the majority of the spreaders... they were there for SEX! So they were swapping all kinds of bodily fluids! It isn't helpful for these people to keep leaving out the actual behavior going on!
Dr. A. Fauxci says
Enough with the masks already. Sweden had no mask mandate (lockdowns or prolonged school closings) but compared to Michigan that did, with roughly the same population, Sweden has approx. 6,500 fewer deaths (not counting collateral deaths the lockdowns caused).
Here are the mask studies, publish them:
I am posting to contribute an anecdote that could be the biggest Red Flag yet where COVID-19 vaccination safety is concerned.
There is a third-party report in a Medscape forum for healthcare workers (only) who have had vaccine side effects describing the case of someone who was hired and required to prove prior immunity (presumably associated with childhood vaccines). Tests revealed the employee had the expected immunity (titers). Apparently, however, the individual then took a COVID-19 vaccine and ended up hospitalized after which it was found that the immunity that was established prior to the vaccine was wiped out.
A pre-print study, linked below, may provide an explanation. "Vaccine interference" is the process whereby a vaccine may inadvertently cause unrelated vaccine-induced immunity to weaken. (Sometimes also referred to "viral interference" wherein a vaccine can cause a person to become more prone to other/unrelated viruses.) If the following paper is any indication, how do we know that novel mRNA/DNA COVID-19 vaccines will not undermine other aspects of the immune system, potentially allowing for a resurgence of infectious diseases previously all-but eliminated by vaccines? (Perhaps this will be of limited consequence here but it might be a good idea to keep our eye on the Third World as vaccines become available there to see if other disease outbreaks occur in an unexpected way afterward.)
Yes, this sounds alarmist. However, most of the long-term vaccine safety concerns thus far have been about antibody dependent enhancement (ADE) — which may or may not become evident as vaccine-induced immunity to the first round of COVID-19 vaccines declines. Vaccine interference, on the other hand, could become an exponential problem if immunity to OTHER infectious diseases is eroded away with successive boosters.
Having come to appreciate, as a non-physician, how difficult it is even with due diligence and many years of R&D to develop a safe and effective vaccines — think of Dengue fever in the Philippines, first-generation HPV vaccine trials in India, RSV, etc. — it boggles the mind how anyone with more training in medical and science disciplines could in any way think it is responsible to impose "vaccine mandates" and "vaccine passports". COVID-19 vaccines are novel — mRNA/DNA have not had a long and successful track history for infectious disease use (previously implemented for so-called gene therapy purposes). We are, in turn, using these novel vaccines against novel virus that most likely came out of a lab. And increasingly we are hitching the ability to retain employment, enter a university or shop for groceries to MANDATES — which implies that these vaccines have a long and proven track record which they absolutely do not! Conversely, we were forced to endure a bizarre public health response last year in which off-label, decades-old drugs and early-interventions were frowned upon, with the full force of a media propaganda campaign against them — ending only when an adult film star and a science fiction writer conned The Lancet and The New England Journal of Medicine into publishing a study in which vast amounts of harm were attributed to Hydroxychloroquine (Sturgisphere debacle). With over 600K Americans dead, media nonetheless were flippant about the possibility that China had in any way mismanaged a virus in a lab and to this day it seems to matter little to our gatekeepers and political class that American taxpayer money, funded through the middleman EcoHealth Alliance, may have been responsible for KILLING our friends and relatives, not to mention millions of people around the world with no end in sight even now! For all the talk the past few years on what Russia might have on President Trump, one is forced to ask "What does China hold over everyone else" that we can't get a straight answer from Dr. Fauci?
Every aspect of this pandemic has been handled bizarrely!
Contrast this situation to the CDC/FDA in an earlier era: It took ~450 cases of GBS and ~26 deaths caused the flu vaccine in 1976 to be withdrawn. So how is it that, come hell or high water, it's vaccine passports/mandates for all — even though we now know that vaccines do not stop the spread of COVID-19 among the vaccinated making the matter of passports and mandates AT BEST a moot point?
It is not necessary to wear a tinfoil hat to see that something is terribly wrong with this pandemic picture! There is only so much garden-variety incompetence one can ascribe to public health agencies before one must concede that acting in bad faith is the more rational conclusion.
Now there could be a new Massachusetts/USA variant as the virus has evolved to beat the vaccines there, just as the virus also evolved to beat the vaccines being trialed/administered in the UK, South Africa and India. Why else do we have UK, South Africa and India variants (Delta). Many scientists warned that vaccines would only exacerbate this pandemic.