BA.4 and BA.5 COVID Symptoms: What to Watch For as Infections Climb

The fastest-spreading COVID-19 subvariants yet, the two latest versions of omicron appear to evade protection from vaccines and previous infections more easily than any others before.

As of July 2, the subvariant BA.5 was responsible for nearly 54% of COVID cases in the U.S. BA.4, a similar subvariant, accounted for nearly 17% more, according to the latest data from the Centers for Disease Control and Prevention.

David Montefiori, a professor at the Human Vaccine Institute at Duke University Medical Center, told NBC News that BA.4 and BA.5 are about three times less sensitive to neutralizing antibodies from existing COVID vaccines than the original version of the omicron variant, BA.1. Additional research suggests that BA.4 and BA.5 are four times more resistant to antibodies from vaccines than BA.2. That subvariant replaced omicron as the U.S.'s dominant version of the coronavirus in April.

As both subvariants continue to spread and more infections are reported across the country, what symptoms are people experiencing? And are these symptoms any different from those commonly seen in other infections?

The U.K., where BA.4 and BA.5 infections also account for the majority of recent COVID cases, reported runny nose, sore throat, headache, persistent cough and fatigue as its most common symptoms last week.

Less than one-third of people surveyed reported fevers, according to data from the Zoe COVID Symptom Study, which allows people to self-report symptoms through smartphone apps. The symptoms are consistent with those reported in the spring, when the BA.2 subvariant was dominant in the country.

According to the University of California Davis Health, the reported symptoms of BA.5 are similar to previous COVID variants: fever, runny nose, coughing, sore throat, headaches, muscle pain and fatigue. At this point, there doesn't appear to be a difference in the symptoms seen in BA.4 or BA.5 cases, compared to earlier omicron strains.

Francois Balloux, the director of the University College London Genetics Institute, said while BA.1 and BA.2 are "pretty different...BA.2, BA.4 and B.5 from a neutralizing antibody perspective are essentially interchangeable."

Because of that, people who had BA.2 infections may have some protection from the latest subvariants, he said. While they spread quicker than any others, BA.4 and BA.5 haven’t been found to cause more severe disease, according to doctors.

"There’s really no clear evidence that they’re more or less likely to make people sick and cause severe illness and death," stated Montefiori.

Dr. Nathan Grubaugh, an epidemiologist at the Yale School of Public Health, said people need to understand that variants like Omicron and BA.5 are a natural part of the progression of the virus.

“Delta was never going to be the last variant—and Omicron is not going to be the last one," he said, according to an article on the school's website. "As long as there is a COVID-19 outbreak somewhere in the world, there is going to be something new that emerges.”

The best way to prevent new variants, he and other doctors say, is to get vaccinated and booster shots. If more people are fully vaccinated, the opportunity for the virus to spread and mutate decreases, they contend.