• The viral samples came from two waves of infection in Houston
  • The dominant strains of virus in the second wave contained the Gly614 amino acid replacement in the virus’ spike protein
  • A virologist said the research indicated coronavirus will be hard to control

A study published Wednesday finds the coronavirus has mutated to make itself more contagious, leading to difficulty in treating it and raising potential problems for any COVID-19 vaccine.

The study by researchers in Houston was released as COVID-19 deaths approached 202,000. The study has yet to be peer-reviewed.

The researchers sequenced the genomes of 5,085 samples of the virus from two waves of infection in the Houston area.

“The genomes were from viruses recovered in the earliest recognized phase of the pandemic in Houston, and an ongoing massive second wave of infections,” the researchers said.

The researchers found the dominant strains of virus in the second wave contained the Gly614 amino acid replacement in the virus’ spike protein and produced a higher viral load. There was little evidence, however, the mutation made the virus more virulent or affected the severity of the disease.

A study published earlier by British researchers reached much the same conclusion in an examination of 25,000 samples gleaned from Europe.

“The findings will help us to understand the origin, composition, and trajectory of future infection waves, and the potential effect of the host immune response and therapeutic maneuvers on SARS-CoV-2 evolution,” the researchers said.

David Morens, a virologist at the National Institute of Allergy and Infectious Diseases, said the study raises the possibility coronavirus will be difficult to control.

“Wearing masks, washing our hands, all those things are barriers to transmissibility, or contagion, but as the virus becomes more contagious it statistically is better at getting around those barriers,” he told The Washington Post.

“Although we don’t know yet, it is well within the realm of possibility that this coronavirus, when our population-level immunity gets high enough, this coronavirus will find a way to get around our immunity. If that happened, we’d be in the same situation as with flu. We’ll have to chase the virus and, as it mutates. We’ll have to tinker with our vaccine.”

James Musser of Houston Methodist Hospital and one of the study’s authors said, despite the changes, the virus is relatively stable.

“We have given this virus a lot of chances,” Musser told the Post.

Four pharmaceutical companies are conducting phase 3 vaccine trials in the United States. Experts say a safe and effective vaccine could be available widely by spring.