Omicron submarines known as BA.4 and BA.5 now represent 13 percent of new coronavirus cases in the United States, up from 7.5 percent a week ago and 1 percent in early May, according to new estimates from the Centers for Disease Control.
The spread of the submarine adds further uncertainty to the course of the epidemic in the United States, where the number of current cases could be a significant underestimation. However, it remains unclear whether this could lead to a large new wave of infections, or an increase in hospitalizations and deaths, scientists have warned.
The new figures released on Tuesday are based on modeling and missed the mark before the CDC estimates. But the overall trend suggests that BA.4 and BA.5 are the other two Omicron submarines, BA.2 and BA.2.12.1, which together are responsible for most of the U.S. sector, says Dennis Nash. CUNY is an epidemiologist at the Graduate School of Public Health and Health Policy.
“It could happen very quickly,” said Dr. Nash.
Data for BA.4 and BA.5, which were first identified in South Africa in early 2022, remain limited. But these variants seem to spread faster than previous versions of Omicron, such as BA.2, and may be better at evading the immune system’s defenses. So far, there is not much evidence that they cause more serious diseases, although more research is needed.
“How similar is it to us?” He said. “I think it’s possible that we’ll see another wave” that is fueled by BA.4 and BA.5. However, if the United States follows the example of South Africa – which is not a guarantee – the wave could be more modest than the previous wave and lead to a less pronounced increase in hospitalizations and deaths, he said.
Over the past few weeks, the United States has averaged about 100,000 new cases a day, down from 30,000 at the end of March, according to a New York Times database.
Globally, the latest data suggests that BA.4 and BA.5 still represent a relatively small fraction, but this may change in the weeks ahead. In a recent report, the UK Health Security Agency noted that in many countries, two submarines are replacing BA.2 as soon as BA.2 replaces the original version of the Omicron.
In the United States, new submarines are gaining ground. For the week ended June 4, BA.5 was responsible for approximately 7.6 percent and BA.4 for 5.4 percent, up from 4.2 percent and 3.3 percent in the previous week, respectively.
Subverbs have become particularly common in some parts of the southern United States. In areas comprising Arkansas, Louisiana, New Mexico, Oklahoma and Texas, BA.4 and BA.5 have more than one in five infections, according to new statistics.
Wastewater data also highlights the proliferation of submarines. For example, in early May in Missouri, BA.4 and BA.5 states were observed in a small number of sewage sheds or geographic areas where wastewater is fed to a single treatment plant or other storage facility. Subverbs are now more than half identifiable, says Mark Johnson, a virologist at the University of Missouri who is analyzing the state’s wastewater.
Preliminary evidence from laboratory research suggests that immunized people who were infected with the original version of Amicron, known as BA.1, could easily be re-infected with BA.4 or BA.5. (People who are vaccinated are more likely to get better, research suggests.)
In addition to the natural erosion of protection against infection over time, this immunity to disease may explain why new subverbs have been able to spread so quickly.
Sarah Kahalan Contribution.