Daily new coronavirus cases tipped back over 100,000 on Thursday after having fallen below that threshold for the first time since the fall earlier in the week.
The overall trend in recent weeks is still positive, as cases and hospitalizations have fallen from their January highs.
But the 103,000 cases on Thursday, as tallied by the COVID Tracking Project, are a reminder that spread of the virus is still at extremely high levels, and more contagious variants threaten to start another surge upward.
Cases are down 23 percent from last week and 57 percent from the peak in January. Hospitalizations are down 42 percent from their high-water marks, according to the COVID Tracking Project.
But the toll of the virus remains heavy, with about 3,000 people dying every day. Deaths are a lagging indicator, so the drop in cases will take longer to show up there.
And the threat of more contagious variants, particularly one first identified in the United Kingdom, known as B.1.1.7, threatens to undo downward trends.
A race has essentially been set off between the new variants and vaccinations. Experts say the faster people can be vaccinated, the more it will do to prevent a new spike from the variants.
Other precautions remain key, including wearing a mask, avoiding indoor gatherings and maintaining distance from others.
The Centers for Disease Control and Prevention on Thursday emphasized that it is important to wear a mask that fits well, and said that wearing a cloth mask over a medical procedure mask can significantly reduce transmission.