"On Saturday, the U.S. reported a huge number of vaccinations: 4.6 million, more than 50% higher than any previous daily report.
There’s always a reason to look at big increases or decreases with caution, and today is no different.
Usually, the U.S. Centers for Disease Control and Prevention pulls their numbers from state data at 6 a.m. (Remember, vaccinations are logged under this methodology when they are reported, not when they happen.)
Today, the CDC pulled the data much later in the day, according to the agency. That’s a small methodological change that means a big (seeming) increase in doses. But it essentially robs doses from Sunday’s report, presuming CDC goes back to its normal data pull and reporting schedule.
If it had pulled the data at the normal time, today’s reported doses would have been 2.98 million, according to the agency. That’s still a big number -- a record, in fact -- but it’s no 4.6 million.
Look for Sunday’s total to be lower than usual as a result.
In the meantime, the moving 7-day average remains the best measure to watch, since it helps smooth these types of changes. And that average, it’s worth noting, keeps going up."
Methodology and Analysis for the Covid-19 Vaccine Tracker