A couple of weeks ago, I used the limited COVID Special Enrollment Period (SEP) data I had for HealthCare.Gov from the last two weeks of February, plus some limited SEP data from a handful of state-based ACA exchanges, to extrapolate out a rough estimate of how many new Qualified Health Plan (QHP) selections may have happened nationally.
At the time, I estimated that perhaps 18,500 people were enrolling per day nationally the final two weeks of February, and that IF that pace remained the same throughout the entire month of March, it would amount to upwards of 832,000 new people enrolling by the end of March (666,000 via HealthCare.Gov, plus another 166,000 via the 15 state-based exchanges).
It's important to note that this wasn't a hard estimate--I was pretty sure that the actual enrollment pace would slow down somewhat after the inital surge, at least until expanded subsidies via the American Rescue Plan (ARP) were officially available in most states, which didn't happen until April 1st.
At the time, HealthCare.Gov had reported 206,000 Qualified Health Plan (QHP) selections as of February 28th. I also had some partial COVID SEP data from a handful of the state-based ACA exchanges, as of various dates. I had 225,000 QHPs confirmed nationally.
At the time, I concluded that based on the enrollment pace of the first few weeks...
As noted above, Medicaid expansion states have only increased average SEP enrollment by around 2/3 as much as Non-expansion states. Since all 15 state-based exchanges have expanded Medicaid, this suggests that the 206K via HC.gov probably represents more like 80% of the total, meaning perhaps 258,000 nationally (~168,000 more than average).
When President Biden announced that HealthCare.Gov would be re-launching an extended Special Enrollment Period in light of the ongoing COVID-19 pandemic, I wasn't surprised at all; in fact, I would have been shocked if he hadn't ordered the HHS Dept. to do so. I was surprised by how long the new COVID Enrollment Period would be: A full 3 months (I had been expecting either 30, 45 or perhaps 60 days at the outside).