The Data Behind the CDC’s New Masking Recommendations

As a result of massive summer gatherings in and around Cape Cod, hundreds of vaccinated people tested positive for COVID-19 with viral titers similar to unvaccinated patients.

black and white photograph of stephanie melchor
| 2 min read
photograph of blue surgical masks overlaying one another

Register for free to listen to this article
Listen with Speechify
0:00
2:00
Share

ABOVE: © ISTOCK.COM, GEORGECLERK

Large public gatherings are associated with SARS-CoV-2 breakthrough infections—detectable virus in fully vaccinated people—according to a report the US Centers for Disease Control and Prevention released Friday (July 30). According to multiple outlets, the data prompted the agency’s shift earlier last week to again recommending that vaccinated people wear a mask indoors in some circumstances.

The report focuses on 469 COVID-19 cases identified in Barnstable County, Massachusetts during July 2021 that were sparked by public summer gatherings. Approximately three-quarters of the cases were breakthrough infections, and of the cases that were DNA-sequenced, 90 percent were caused by the Delta variant.

In addition to the startling number of cases in fully vaccinated people, the report found that the vaccinated patients had comparable viral loads to the unvaccinated patients, which could indicate a capacity for transmission. Although this finding “just gives you an indication of how much viral ...

Interested in reading more?

Become a Member of

The Scientist Logo
Receive full access to more than 35 years of archives, as well as TS Digest, digital editions of The Scientist, feature stories, and much more!
Already a member? Login Here

Keywords

Meet the Author

  • black and white photograph of stephanie melchor

    Annie Melchor

    Stephanie "Annie" Melchor is a freelancer and former intern for The Scientist.
Share
Image of small blue creatures called Nergals. Some have hearts above their heads, which signify friendship. There is one Nergal who is sneezing and losing health, which is denoted by minus one signs floating around it.
June 2025, Issue 1

Nergal Networks: Where Friendship Meets Infection

A citizen science game explores how social choices and networks can influence how an illness moves through a population.

View this Issue
Unraveling Complex Biology with Advanced Multiomics Technology

Unraveling Complex Biology with Five-Dimensional Multiomics

Element Bioscience Logo
Resurrecting Plant Defense Mechanisms to Avoid Crop Pathogens

Resurrecting Plant Defense Mechanisms to Avoid Crop Pathogens

Twist Bio 
The Scientist Placeholder Image

Seeing and Sorting with Confidence

BD
The Scientist Placeholder Image

Streamlining Microbial Quality Control Testing

MicroQuant™ by ATCC logo

Products

The Scientist Placeholder Image

Agilent Unveils the Next Generation in LC-Mass Detection: The InfinityLab Pro iQ Series

parse-biosciences-logo

Pioneering Cancer Plasticity Atlas will help Predict Response to Cancer Therapies

waters-logo

How Alderley Analytical are Delivering eXtreme Robustness in Bioanalysis