A study of over 5,000 virus samples from the Houston area discovered a mutation to the COVID-19 virus that potentially makes it more contagious.

In the first phase of testing, 71% of the virus samples had the mutation, while 99.9% of the samples from the second phase had the mutation, according to the study. 

Study co-author Ilya Finkelstein said the researchers did not find evidence that the virus became more deadly from the mutation, nor any evidence the current vaccines being developed would not work with this mutation.

“Every time the virus infects us, it changes its own genetic information,” said Finkelstein, a UT molecular biosciences associate professor. “Most of these changes are probably not going to make the virus more dangerous. Some of them are what are called neutral changes … some of them probably weaken the virus … and some of them make the virus perhaps more virulent.”

A more virulent virus is better at evading the host’s immune system, according to Science Direct. The mutation allows the virus to attach to and enter host cells in humans more quickly, Finkelstein said.

Finkelstein said the mutation has been widespread globally; it was the version of the virus seen in Italy during their peak. He believes it was most likely introduced to Houston through one of the major airports, then rapidly spread in the community.

“Patients are not sicker, but it is easier to get sick with that strain,” Finkelstein said. “When patients came in with that particular variant of the virus, the number of viral particles in them was higher. Again, it shows that the virus is replicating more readily when it has that particular mutation.”

The study was conducted with samples from the Houston Methodist Hospital health system, which spans the greater Houston metropolitan area and provides a large, diverse set of patients, said S. Wesley Long, the primary investigator for the study. 

Long said the team also found new mutations that may be important for vaccine development.

“Mutations occur randomly, but as we start to roll out vaccines and start to roll out new therapies and put that selective pressure onto the virus in the population, the more likely it is that there may be a mutation that will allow the virus to escape a treatment or a vaccine,” Long said. “Then those (versions of the virus) could then be very successful in the population, so we need to continue to monitor for those.”

The samples represented about 10% of all COVID-19 cases in metropolitan Houston during the study period, according to the study. Finkelstein said the team is continuing to monitor the virus for mutations.

“We're now enrolling many more patients, and making sure we trap this third wave to stay one step ahead of the virus,” Finkelstein said. “We're trying to figure out whether the virus is becoming more resistant to our immune systems.”