The U.S. Government makes periodic releases of VAERS data. Each release is dated according to the latest report placed in the system, so if the release is dated March 2, that means it has all reports that have been entered into VAERS as of March 2.

In the past, the government released data monthly, and the date of the release was the previous month. For example, they would post data on October 17 with data up to September 14. The data quickly grew old, because the October 17 release would remain current until November 17 when the next release came out, and by then, the September 14 data would be over two months old.

Since the availability of Covid vaccines, the government has begun weekly releases of the data, and each week's data is only one week old. For example, the release made on January 22 included data up to January 15, and this release remained current until the January 29 release, by which time the data was two weeks old.

Medalerts.org updates the data as soon as the government releases it, usually within hours of posting. If you look at the government's search engine, CDC Wonder, you will see the same date as MedAlerts. The two sites are in complete sync, because they are both fed from the government's data releases.