Under CDC recommendations, everyone in Terrebonne and Lafourche should wear masks indoors
In Louisiana, all 64 parishes have COVID transmission rates so high the CDC recommends everyone wear masks while indoors.
The Centers for Disease Control and Prevention recommends that even vaccinated Americans resume wearing masks indoors if they are in areas with high transmissibility of the COVID-19 virus.
The guidance also recommends people with underlying conditions that may make them more susceptible to the coronavirus wear masks, along with anyone living with vulnerable people. Teachers, school staff, students and visitors inside schools from kindergarten to 12th grade also fall under new guidance recommending universal mask-wearing.
For vaccinated people in just under half of the counties and parishes in the country — places with high transmissibility — that means masks are recommended to be commonplace indoors once again.
The delta variant, which continues to make up more than 80% of new infections in the U.S., is more than two times as transmissible than the original strains of COVID-19, and experts believe it could cause vaccinated people to be contagious.
"This new science is worrisome and unfortunately warrants an update to our recommendations," CDC director Dr. Rochelle Walensky said in a briefing Tuesday.
Here's what transmissibility is and how to find out if you're in an area where you should start masking indoors again.
What is high transmissibility?
Community transmission is calculated using two metrics:
► How many new cases per 100,000 persons have occurred in the last seven days.
► The percentage of positive diagnostic and screening tests in the last seven days.
Counties are categorized as having low, moderate, substantial or high transmissibility.
Transmissibility is considered high when there are 100 or more new cases per 100,000 in the last seven days and 10% or higher positive COVID tests in that period.
How are Terrebonne and Lafourche faring?
Both parishes far exceed the CDC's minimum criteria for high transmissibility.
Terrebonne: New cases per 100,000 persons totaled 391 for the week ending Saturday -- nearly four times the level the CDC uses to rank the spread within a community as high. The figure rose 85% from the previous seven-day period.
Lafourche fared worse: It recorded 646 new cases per 100,000 persons for the week ending Saturday, up 104% compared to the previous seven days.
Positivity rates in both parishes also are much higher than the 10% the CDC considers high. The rate was in 17% Terrebonne and 16% in Lafourche for the week ending Saturday, CDC data shows.
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Both parishes' vaccination rates are below Louisiana's average of 36.5% and the U.S. average of 49%. Louisiana has third-lowest rate among states. As of Tuesday, 29% of Terrebonne residents and 33% in Lafourche were fully vaccinated, state Health Department figures show.
This past week, five Louisiana parishes reported their largest-ever increases in new COVID-19 cases. Ascension, Lafourche, Livingston, St. Mary and Tangipahoa account were five of nine counties and parishes across the nation to set new records for growth in COVID-19 cases last week.
Where is COVID spreading at a high rate?
Just under half of all U.S. counties, 46.43%, are now identified as having high COVID transmission, according to the CDC, an increase of over 17% from seven days ago.
Counties with the likelihood of substantial transmission make up 17.02% of the U.S., 27.2% of counties are considered at a moderate level, and 9.31% are at a low level.
States with a large concentration of high-transmission counties are mostly in the South and some Western states, like Utah, according to the CDC's COVID tracker.
In Louisiana, Florida and Arkansas, everyone should wear a mask in indoor public spaces, according to the latest CDC guidance, because each county and parish in the three states is a high-transmission community.
In Mississippi, Alabama and Missouri, nearly every county is at a high level on the map.
Transmissibility is lower in areas of the Northeast and some parts of the Midwest. Nearly all of the counties in New York, Pennsylvania and Minnesota, for example, are in the moderate or low categories.
How to find out if you're in a high-transmissibility area
The CDC provides a COVID data tracker that includes a by-county view of transmissibility rates each week.
You can enter your state, county or metro area to find out what the transmissibility is like where you live by visiting bit.ly/COVIDtrackerCDC.
-- Jeanine Santucci is a reporter with USA TODAY. Keith Magill is executive editor of The Courier and Daily Comet.