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CDC document: Delta variant as contagious as chickenpox

Vaccines remain very effective at preventing severe illness from the delta variant, however.

A federal document from the Centers for Disease Control and Prevention (CDC) says the delta variant of the coronavirus is as transmissible as chickenpox, and more contagious than ebola, the common cold, smallpox, MERS, SARS and even the 1918 "Spanish" flu. 

The document, obtained by The Washington Post, warns that the delta variant can infect people who are fully vaccinated. Such cases are defined as "breakthrough" cases. Still, vaccine effectiveness remains very strong against severe illness, hospitalization and death. 

Overall, vaccines reduce delta's ability to cause severe disease by 10 fold, while showing a 3-fold reduction in infection. 

The slide below from the CDC document explains that the delta variant is highly contagious and likely causes more severe disease in the unvaccinated, while vaccines are at least 90% effective at preventing severe symptoms. 

Screen Shot 2021-07-30 at 1.27.42 PM

Between July 3-17 in Provincetown, Massachusetts, there were 469 COVID-19 cases identified in Massachusetts residents, and 346 (74%) of them were fully vaccinated people, according to the CDC. Of those infections, 133 samples underwent genomic sequencing and 90% of them were found to be the delta variant. 

However, the CDC notes that there will naturally be more breakthrough cases simply because more and more Americans are getting vaccinated. As The Washington Post stated, the information "echoes data seen from studies in other countries, including highly vaccinated Singapore, where 75 percent of new infections reportedly occur in people who are partially and fully vaccinated."

The CDC document says non-pharmaceutical interventions (NPIs) are "essential to prevent continued spread with current vaccine coverage." NPIs include social distancing and wearing a mask. 

Earlier this week, the CDC changed its masking guidance by urging everyone, even the vaccinated, to wear masks indoors in communities with "substantial or high" virus circulation. There are more than 30 counties that meet that criteria in Minnesota, according to a Friday update. 

CDC - MN counties high or substantial transmission - July 30, 2021

The Minnesota Department of Health says approximately 75% of all cases that have undergone genomic sequencing in July have been identified as the delta variant. Delta is fueling the state's rising case counts and hospital admissions. 

The state reported more than 700 new cases Friday, along with 231 people hospitalized with COVID-19, including 64 patients in intensive care. The 64 ICU admissions are the most since June 3 and the 167 non-ICU admissions are the most since June 4.

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