Confirmed coronavirus infections in the United States have quadrupled in July, according to Washington Post tracking. Earlier this week, the Centers for Disease Control and Prevention urged vaccinated people to resume wearing masks while indoors in parts of the country where transmission is high.

The summer surge in coronavirus cases is because of the highly transmissible delta variant of the virus. Research suggests the delta variant is more contagious than past variants and more transmissible than the original variant detected in China. First found in India last year, the strain now accounts for most of the new infections in the U.S.

Washington Post science reporters Joel Achenbach and Ben Guarino, who have been covering the pandemic (and, in Guarino’s case, authoring our coronavirus newsletter), answered your questions about the rise of the delta variant on Friday, July 30. Here are some of the questions they’ve answered so far:

Send us your question below. The question box includes a space for your name, but this is optional. Your question may be edited for accuracy and clarity.

Looking for more? Read The Post’s coverage of the delta variant:

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Teddy Amenabar, an editor on The Post’s audience team, produced this Q&A.