National COVID-19 trends, March 18

Here are the latest national COVID-19 trends, according to the U.S. Centers for Disease Control and Prevention (CDC) and major wastewater surveillance providers:

• About 2 in every 100,000 people were hospitalized for COVID-19 during the week ending March 1.
• COVID-19 test positivity has decreased 5%, from 4.0% of COVID-19 tests returning positive results during the week ending March 1 to 3.8% of tests during the week ending March 8.
• SARS-CoV-2 concentration in wastewater has decreased 5% between the week ending March 1 and the week ending March 8, and the national wastewater viral activity level is “low,” per the CDC.
• SARS-CoV-2 concentration in wastewater has increased 0.5% between February 26 and March 5, and the national wastewater trend is “medium,” per WastewaterSCAN.
• Healthcare visits for influenza-like illness have decreased 12% between the week ending March 1 and the week ending March 8.

COVID-19 declines continue in the U.S., though the changes in disease levels have been relatively minor this week. While we are in a lull between surges, SARS-CoV-2 levels (as measured in wastewater) remain much higher than the early years of the pandemic — and higher than lulls last spring and fall. Meanwhile, health officials are now applying the same tactics used to minimize COVID-19 to other diseases.

Viral levels in wastewater went down slightly in the first week of March, according to the CDC and Biobot Analytics. The CDC reported a 5% decline in its national average between March 1 and March 8, while WastewaterSCAN reported a 0.5% increase between February 26 and March 5. Biobot reported a decline for the week of March 8, but no longer shares exact numbers in its reports. The discrepancy between surveillance networks is likely due to differences in timing and testing site locations.

Wastewater and emergency department data indicate that the Midwest and South have more COVID-19 hotspots at the moment. The CDC reports that the South has the highest coronavirus levels in wastewater of any region, and reports a slight uptick in the Midwest in its most recent week of data; WWSCAN similarly reports higher levels in the Midwest and an uptick in the South.

COVID-19 cases are “likely growing” in four Southern states as of March 11, according to the CDC’s infectious disease modeling center: Oklahoma, Louisiana, Mississippi, and North Carolina. Cases are also “growing” in Alaska, and are “declining or likely declining” in 28 states, including many across the Northeast, Midwest, and West.

Though the continued declines in COVID-19 metrics are good news, I want to emphasize that this early-spring period has looked pretty different than past years. Rather than a massive winter wave followed by a relative lull, we saw a lower (and perhaps longer) wave — followed by a plateau that is really not too far below the wave’s peak. As influenza and other seasonal diseases decline back to their baselines, COVID-19 remains a risk year-round.

In addition, political leaders and the mainstream media are now taking attitudes that helped COVID-19 spread more and applying them to other diseases. As measles outbreaks continue, health experts criticized Robert F. Kennedy Jr. recently for falsely claiming that one measles infection provides a patient with “lifetime protection” from future infections, echoing similar misinformation about COVID-19. In fact, we need many layers of precautions to protect against infectious diseases — including the masks that many pundits are now too scared to mention.

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