How worried should Allegheny County residents be about the Delta variant?

by Juliet B. Martinez

The Delta variant is a strain of COVID-19 that was first detected in India, where it quickly became the dominant strain. It has been identified in 85 countries and is spreading rapidly among unvaccinated populations. Between May 8 and June 5, the Delta variant jumped from representing 1.3% of new cases in the United States to 10%. It now accounts for more than half of all new COVID-19 cases nationwide. Not only is this strain more contagious, doctors are reporting that it causes more severe illness and a faster onset of serious symptoms.

Overall COVID cases in Allegheny County remain low, largely showing the success of vaccination efforts. Those who have not been vaccinated face increased risk, and while vaccines are effective, research shows that illness is still possible. To help understand the variant, we’ve answered key questions about its spread and the risk it poses.

What is a viral strain or variant?

Imagine that an artist releases a song, and it’s moderately successful. Several other artists interpret it and some are flops while others are about as successful as the original. Eventually, as different singers perform it, each tweaking it slightly, the song evolves into something really catchy and it becomes a big hit. That’s kind of how a highly contagious variant arises. 

Every time someone is infected with COVID, the virus uses the person, its host, to produce millions of copies, like cover versions. With every breath, cough and sneeze, the host sends these copies into the air to infect others. But not every copy is perfect; viruses can’t correct errors in their genetic code, so the “melody” gradually changes. As a result of these small changes and the millions of times the virus copies itself in a series of hosts, the virus’ genes eventually change enough that many new strains or versions emerge. Some of those are more “catchy” than others; they spread more easily or cause more severe illness. Ultimately, the more people infected and making copies of the virus, the more likely one of those copies will give rise to a hit like the Delta variant.

How widespread is the Delta variant in Allegheny County?

Allegheny County Health Department Director Dr. Debra Bogen said during a June 30 briefing that the Delta variant was specifically identified in two cases in Allegheny County, one in April and one in May. Because testing in many cases doesn’t check for the variant, it is not known what percentage of local cases it represents. Overall, the case numbers in June were extremely low, with an average of 16 new cases per day. More than 47,000 people were tested for COVID in June, but only around 1% tested positive. That means the virus appears to be reasonably under control here.  

This is due largely to the success of vaccination efforts. More than half of eligible teens have had at least one shot, but that rate goes up to 62% for adults ages 20 to 34, 71% of those between 35 and 49, 79% of adults aged 50 to 64 and close to 100% of adults over age 65. These vaccination rates are preventing COVID from spreading widely in Allegheny County, but there is room to improve, especially in younger populations. 

What if I’m vaccinated?

One of the biggest questions is whether the vaccines approved for use in the United States protect against the Delta variant. Research suggests that they do, almost as well as they protect against the original COVID strain and the Alpha variant (previously known as the UK variant or B.1.1.7), which is currently the most dominant variant in the United States. 


(Photo illustration by Natasha Vicens)


How worried should Allegheny County residents be about the Delta variant?


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