You Can’t Find What You Don’t Look For: Delta Makes Testing Even More Critical

In our can't miss blog about the COVID-19 Delta Variant, we discuss the variant's contagiousness and how testing and vaccines are impacted.

Liz Ruark
COVID-19 Delta coronavirus image

As of September 20, 2022, this post will no longer be updated. 

The Delta variant of SARS-CoV-2, the virus that causes COVID-19, is at least twice as contagious as it used to be. The COVID-19 game has changed.

What does that mean for all of us?

To answer that question, let’s start by looking at a measurement called R0. R0 tells you how many people one person with COVID-19 is likely to infect; it’s a measure of how transmissible the virus is. The original or “wild type” of SARS-CoV-2 had an R0 of about 2.5: On average, one person who had the disease would spread it to about 2.5 other people. The Delta variant has an R0 of somewhere between 5 and 8. (Yikes!) Here’s what that looks like, assuming a low-end estimate of Delta’s transmissibility:

Comparison of Contagiousness

Given that one infected person can now infect so many people, it’s even more critical to find and isolate those folks as quickly as possible. And the way to find them is to test for the virus, because many of them are contagious before they even know they’re sick.

By the way, if you’re worrying about whether current tests for COVID-19 can pick up cases of the Delta variant, don’t. The CDC and test manufacturers keep a close eye on that sort of thing, and they confirm that the tests continue to work. (Current COVID-19 tests won’t tell you which variant of the virus you have – that’s a separate thing.)

And you know what else still works against Delta? Vaccines. Yes, you’ve heard that fully vaccinated people can still get infected with Delta — you probably know someone who has been. That’s happening for two reasons: 1) The higher the percentage of vaccinated people in a population, the more likely it is that someone who gets infected has been vaccinated, and 2) the vaccines are a bit less effective at preventing infection with Delta than they were against previous variants.

BUT: Vaccinated people who get COVID-19 are far less likely to get severely ill or die than unvaccinated people are. In mid-July, as the Delta surge was taking off, 97% of people hospitalized with COVID-19 were unvaccinated.

Vaccines are not a magical force field that makes it impossible for you to get infected. That’s why other COVID-19 mitigation measures, especially wearing a high-quality mask when indoors in public or with large groups of people, is still important, especially now that we’re facing the Delta variant. It’s why ventilating buildings properly is still important. It’s why using air cleaners when good ventilation isn’t possible is still important. It’s why testing is still important.

You can’t find what you don’t look for, and the way to look for the virus is to test for it. The WhenToTest Planner will tell you how often you need to do it in order to decrease the chance of an outbreak in your organization. Check it out today.

Looking for COVID-19 tests? Visit our partners! Compare different test brands at ASU’s Connect to Test and find quality testing supplies at Project N95.