CDC's "Nowcast" estimates that omicron likely became the dominant variant in the United States late last week. But experts say that America's understanding of the variant's spread is limited and comes with considerable uncertainty, underscoring the shortcomings of the United States' Covid-19 surveillance.

The policies Biden and states could use to control the omicron variant

Omicron is likely the dominant strain in the U.S.

Data from the World Health Organization's (WHO) newest weekly epidemiological report showed the United States had the highest number of new cases in the world last week—at 725,750, between Dec. 13 and Dec. 19—CNN reports. On a global level, WHO estimated there were 4.1 million new Covid-19 cases over that same time frame.

The omicron variant: The 'good,' 'bad,' and 'ugly' scenarios

According to CNN, the delta variant remains the dominant coronavirus strain globally. However, WHO's weekly report showed that the omicron variant, which has been confirmed in 106 countries, is surging and poses a significant risk.

"Recent evidence indicates that [the] omicron variant has a growth advantage over the delta variant and is spreading rapidly, even in countries with documented community transmission and high levels of population immunity," WHO said. 

This data appeared to align with new CDC data released Monday via the agency's "Nowcast" variant surveillance data, STAT News reports. According to "Nowcast," the omicron variant likely became the most common variant in the United States at the end of last week.

That said, some experts caution that CDC's numbers from the last two weeks have been estimated using models that likely contain sizable margins for error. Nonetheless, the estimates seem comparable to the limited real-world data from countries where omicron was detected early on, STAT News reports.

Notably, STAT News said CDC estimates indicated that hospitalizations are increasing at a more modest rate than the increase in overall cases—although this could change going forward, as hospitalizations tend to lag behind case reports.

For its part, WHO said of the recent global surge in cases, "Given rapidly increasing case numbers, it is possible that health care systems may become overwhelmed. Preliminary data suggest that there is a reduction in neutralization of omicron in those who have received a primary vaccination series or in those who have had prior SARS-CoV-2 infection, which may suggest a level of humoral immune evasion."

As a result, WHO said that "the overall risk related to the new variant of concern omicron remains very high."

Why the U.S. struggles to track Covid-19 case numbers  

Amid surging omicron cases, health officials and scientists in the United States still struggle to gather reliable data almost two years into the pandemic, Politico reports.

Part of the issue is that even though most Covid-19 tests can detect the coronavirus, they can't identify each individual variant. That's because the tests detect parts of the virus that don't typically change. To determine which variant is present, a sample needs to be sent out to a lab to be genetically sequenced. According to experts, this has created a weakness in the United States' surveillance of coronavirus variants, leaving the country to rely mostly on data from other countries.

Covid-19 tested national health systems—and they responded largely as designed

According to Politico, this continued dependence on international data—even now, nearly two years into the pandemic—highlights the degree to which U.S. public health data has failed to produce accurate, timely data on both the spread of the virus and the degree to which it evades the vaccine. 

"I think we've done a horrible job from day one in data tracking for the pandemic," said Eric Topol, a professor of molecular medicine at Scripps Research and former advisory board member of the Covid Tracking Project. "We're not tracking all the things that we need to get a handle on what's going on. It is embarrassing."

Separately, National Institute of Allergy and Infectious Diseases Director Anthony Fauci said there's data "coming in from the U.K., … from Israel, [and] … from South Africa, which is ahead of the rest of the world in the experience they're having with omicron." But while that's enabled the United States to get the "virus either in the live virus form or in the pseudo virus form, … we don't have enough of this in the United States to be able to bank on our own clinical experience which is in contrast to the South Africans who are in real time experiencing the clinical impact of omicron."

In conversations with Politico, several public health experts said the federal government needs to invest more in the nation's surveillance systems so they can better handle another surge in Covid-19 surge or a new pandemic.

CDC has made recent financial investments to improve genomic sequencing and data systems. However, the agency—as well as various state and local public health departments—rely on outdated data systems that are often dependent on manual data input, subject to slow lab turnaround times, and suffering from a shortage of public health workers. And Politico reports that, according to state officials, CDC's recent financial investments on this front will likely take "several years to implement" as well as sufficient federal funding.

"It will be very important that we identify ways to have sustainable support for these non-categorical activities like data modernization," said Dan Jernigan, the deputy director of the CDC's Public Health Science and Surveillance office. He added, "That's something that we look to our partners in Congress to identify how best to support the ongoing need for maintaining a good data infrastructure."

And until the United States has a sufficient data-tracking system for this type of surveillance, experts told Politico the country will still depend on other nations' data.

"We're relying on everyone else's data. We should be providing data to the world and we are not," said Zeke Emanuel, a bioethicist and former member of President Joe Biden's transition Covid-19 advisory board. "We started [the pandemic] with a serious problem of not enough data and bad data infrastructure. We have not made the structural investments we need. The ideal is that we have real time data. And we don't have that. We're not even close to that." (Langmaid, CNN, 12/21 [1]; Parker, STAT News, 12/21; Langmaid, CNN, 12/21 [2]; Banco, Politico, 12/21)