Delta variant: Facts from our experts

woman walks at UT Health San Antonio wearing a mask.

Contact: Will Sansom, (210) 567-2579, 

As children return to area schools this month, here are some points of interest about the delta COVID variant from experts at UT Health San Antonio:

  • The delta variant is much more infectious. A carrier, even if asymptomatic, can infect an average of eight other people (compared to two on average with the first COVID-19 virus).
  • Young people are contracting COVID. Most senior adults have been vaccinated, and the variant is moving through unvaccinated younger people.
  • The delta variant spreads through vaccinated people as well as the unvaccinated. Cases of COVID in fully vaccinated individuals are called “breakthrough” cases.
  • Based on the number of community cases, San Antonio is in a fourth COVID surge.
  • Models predict, if behaviors continue such as unmasking in large crowds, that this spike will be comparable to previous surges.
  • We are heading into the fall and virus season when illnesses such as the flu increase. This can complicate the pandemic.
  • In laboratory testing, 98% of samples are the delta COVID variant.
  • The delta variant seems to have a shorter incubation time, and COVID testing is recommended three to five days after close contact with a COVID-positive individual rather than eight days as was the past recommendation.
  • If you are sick, even just a stuffy nose, then stay home and get tested. The delta variant often presents with nasal congestion.
  • All eligible people are urged to get the COVID vaccination as soon as possible. Unvaccinated parents of children 11 and younger are especially urged to get it. Anyone around younger children, including parents, home caregivers and teachers, should be vaccinated.
  • Wearing a mask at school is strongly recommended at all grade levels.
  • Even the vaccinated should wear a mask in public and practice social distancing.

Reviewed by Robert Leverence, MD, and Thomas Patterson, MD.

The University of Texas Health Science Center at San Antonio, also referred to as UT Health San Antonio, is one of the country’s leading health sciences universities and is designated as a Hispanic-Serving Institution by the U.S. Department of Education. With missions of teaching, research, patient care and community engagement, its schools of medicine, nursing, dentistry, health professions and graduate biomedical sciences have graduated 39,700 alumni who are leading change, advancing their fields, and renewing hope for patients and their families throughout South Texas and the world. To learn about the many ways “We make lives better®,” visit

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