When Should I Worry About...

3 Things to Know About the COVID-19 Delta Variant

July 30, 2021 - Katie McCallum

The day-to-day challenges of the COVID-19 pandemic have brought many new questions. Many, many, many new questions.

Some of the more pressing questions are regarding the Delta variant. Will it cause another wave? Will we have another lockdown? Can it escape our current vaccines?

"A new wave is hitting us now. COVID-19 cases are again rising across the country, particularly in the Houston metroplex, with the Delta variant accounting for the vast majority of new cases," says Dr. Randy Olsen, professor of clinical pathology and genomic medicine at Houston Methodist. "This variant is showing us how concerning it is, and it underscores the need to continue vaccination efforts."

Here are three key things Dr. Olsen wants you to know about the COVID-19 Delta variant:

1. The Delta variant is indeed concerning

What makes the Delta variant concerning?

For starters, it spreads much easier than other variants.

"Studies have found the Delta variant family of viruses (also referred to as the India variant or B.1.617 variant) to be more contagious than the Alpha variant (also referred to as the U.K. variant or B.1.1.7 variant), which had been the predominant strain in Houston previously" says Dr. Olsen. "Consistent with its ability to easily spread, the Delta variant is now the dominant strain in the Houston metroplex. We’ve detected the Delta variant in people residing in nearly every zip code in our region."

In addition, the Delta variant is able to cause more severe disease.

"The Delta variant causes more severe infections and more hospitalizations," says Dr. Olsen. "Importantly, though, it's mostly infecting the unvaccinated, which underscores the need to vigorously continue vaccination efforts."

The recent increase in infections caused by the Delta variant is an important reminder that this pandemic isn't over, and that anyone who is eligible to get vaccinated should do so as soon as possible.

Variants such as Alpha and Delta arise during the course of infection and transmission, so the longer we let this virus spread, the more likely that new concerning variants will emerge.

Dr. Olsen insists, "Vaccine-induced immunity is our best tool to overcome the pandemic."

2. Vaccines are still highly protective against the Delta variant

"Overall, research has found that individuals who are fully vaccinated are well-protected from the Delta variant," says Dr. Olsen. "Studies clearly demonstrate that the vaccines used in the U.S. remain highly effective in preventing serious illness and hospitalization."

Fully vaccinated means meeting some specific criteria, though. You're fully vaccinated only after two weeks have passed since receiving either:

  • Your second dose of the Pfizer or Moderna vaccine OR
  • Your first (and only) dose of Johnson & Johnson's vaccine

"Even if you’re vaccinated, it's still a good idea to take general safety precautions. This includes wearing masks and social distancing when in situations where everyone may not be vaccinated, such as in grocery stores or at social events with individuals outside of your known circle of family and friends," adds Dr. Olsen. "The chance for infection is much, much, much more likely for unvaccinated individuals than vaccinated ones. Breakthrough infections are possible, but they are quite uncommon and tend to be asymptomatic or very mild.”

This is why the CDC recently updated its mask recommendations for vaccinated individuals. If you are in an area of substantial or high transmission, it is recommended that you wear a mask indoors in public. (Related: 5 Things Vaccinated People Need to Know About Breakthrough Infection)

Dr. Olsen adds, "Always be aware of your surroundings and exercise COVID-19 precautions when appropriate."


3. The time to get vaccinated is now 

Until recently, the Alpha variant was the dominant strain in the Houston metropolitan area. However, during recent weeks, the Delta variant overtook Alpha as the most common cause of new infections. The Delta variant now accounts for 89% of new infections in the Houston metropolitan area.

"We saw the Delta variant initially enter the Houston community in mid-April. Since then, the number of infections caused by Delta has increased week over week," Dr. Olsen warns. "This pattern is similar to what was seen with the Alpha variant here in Houston and in the U.K. earlier this year, and more recently with the Delta variant in the U.K."

What’s just as concerning as the rising cases of the Delta variant is the fact that far too many people are still unvaccinated. (Related: How Soon Can You Get Vaccinated After Recovering From COVID-19?)

Dr. Olsen insists, "If you're not yet vaccinated, now is the time. Vaccination will protect you from the Delta variant (and others including the Alpha variant), and, in the end, is our best way out of the pandemic."

Next Steps:


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All individuals age 12 and older are currently eligible to receive a COVID-19 vaccine in Texas.

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