New modeling from the Centers for Disease Control and Prevention (CDC) estimates the BA.2 Omicron variant is now dominant in the United States. In related news, the Food and Drug Administration (FDA) has withdrawn its emergency use authorization for the COVID-19 antibody treatment sotrovimab as research has found it ineffective against the BA.2 variant.
Since the pandemic began, the CDC has been tracking the prevalence of different SARS-CoV-2 viral strains in the country through its National SARS-CoV-2 Strain Surveillance program. The program analyzes viral samples from all over the country to estimate the predominance of emerging variants.
As the genetic surveillance work takes a couple of weeks to formally collect, the CDC also has a model called Nowcast that estimates current variant proportions. As of the start of April, the CDC’s Nowcast modeling estimates the BA.2 Omicron variant accounts for 72.2 percent of all COVID-19 infections in the United States.
The last recorded real variant prevalence rate cited by the CDC was for the week ending March 19, estimating BA.2 accounting for 42.4 percent of all infections in the country. The spread of BA.2 has been dramatically rapid, with the CDC estimating at the end of January the variant only accounted for 1 percent of all infections in the country.
In a recent White House press briefing CDC Director Rochelle Walensky said there is no evidence so far to indicate BA.2 leads to more severe disease than other forms of Omicron that have been circulating. However, she also said BA.2 “does appear to be more transmissible.”
BA.2 initially emerged back in November 2021. It was one of three distinct SARS-CoV-2 variants that the World Health Organization ultimately incorporated under the one Omicron moniker. It has been estimated to be around 10 to 15 percent more transmissible than the initial iteration of Omicron.
In response to the increasing prevalence of BA.2 in the country, the FDA has revoked its emergency use authorization for sotrovimab, a once-promising monoclonal antibody treatment for COVID-19 that has recently proven ineffective against this variant. This decision comes just weeks after the FDA halted use of two other monoclonal antibody treatments. An antibody cocktail from pharmaceutical company Eli Lilly (bamlanivimab and etesevimab) and Regeneron’s infamous antibody cocktail were both found to be ineffective at treating COVID-19 cases with the BA.1 type of the Omicron variant.
This leaves doctors in the country with fewer treatment choices for severe COVID-19 cases. The only monoclonal antibody so far proven to work against BA.2 is a new treatment called bebtelovimab, which was authorized by the FDA two months ago.
Alongside this monoclonal antibody, the FDA recommends three currently available antiviral treatments that are expected to still work effectively against BA.2. These include the two SARS-CoV-2 specific antivirals – Paxlovid and Lagevrio – and the intravenously administered remdesivir.
According to Walensky, the United States is currently experiencing a quiet lull in the pandemic. Weekly average case loads are down and COVID-19 hospitalizations are at one of their lowest points since the pandemic began in 2020.
The big question is whether the rapidly emerging BA.2 variant will trigger a new wave in the pandemic. The variant has caused significant spikes in cases and hospitalizations across Europe in recent months. The United Kingdom, for example, currently has more people in hospital with COVID-19 than it has seen in over 12 months.
Walensky is optimistic the United States should be somewhat protected from a severe BA.2 wave, but she does urge everyone in the country to make sure they have had their vaccine booster shots.
“The high level of immunity in the population from vaccines, boosters, and previous infection will provide some level of protection against BA.2,” Walensky said. “However, we strongly encourage everyone to be up to date on their COVID-19 vaccines.”
Source: CDC, FDA, White House