Supply vs Demand: Which States are Reaching their COVID-19 Vaccine Tipping Points?

We recently estimated that the U.S. was close to its “COVID-19 vaccine tipping point” – that is, the point at which vaccine supply may start to outstrip demand.  We also noted that national averages may mask important differences by state. We therefore sought to understand where states fall along this spectrum; such differences are important for understanding how best to target efforts to increase vaccine coverage throughout the country.

To do so, we looked at the share of adults with at least one vaccine dose by state, daily rates of first doses administered (using a 7-day rolling average), and how this rate has changed in the last week (see methods). We were particularly interested in identifying states that may still have relatively low vaccine coverage (i.e., below 50% of adults 18 or older) coupled with evidence of a decline in the uptake of first doses, as these states may present the biggest challenges for achieving sufficient vaccine coverage in the U.S.

As of April 29, among the 50 states and DC, we find that:

The share of adults who had received at least one vaccine dose was 55% overall, and ranged significantly across the country from a low of 41% (Alabama) to a high of 74% (New Hampshire). In addition, there is evidence of a decline in the pace of new uptake in most states. The daily rate of first dose administration at the national level is 440 per 100,000, ranging from 136 per 100,000 (Mississippi) to 889 (Rhode Island). Most states (31 of 51) are vaccinating below the national rate, reflecting the fact that vaccination rates are generally higher in larger states (e.g., California). Furthermore, the rate of first dose administration per 100,000 in the last week dropped for the U.S. overall (-17%) and for almost every state (45 of 51) (see Table 1).

At the higher end of the vaccine coverage spectrum, more than 60% of the adult population has received at least one dose in 12 states. These states are primarily in the Northeast (8 of 12). Seven have vaccination coverage of at least 65% and all but 3 (New Hampshire, New Mexico, and Pennsylvania) are administering first doses at well above the U.S. rate. Eight of the 12 states have seen declines in first dose administration rates over the past week, suggesting that these states may be approaching or have reached demand saturation, albeit at relatively high vaccination coverage levels and rates of administration.

 

At the lower end of the vaccine coverage spectrum, less than 50% of the adult population has received at least one dose in 13 states, including 6 that are below 45%. Nine of these states are in the South and in all, the daily rate of first vaccination per 100,000 is below the national rate. Moreover, most are experiencing declines in the rate of first doses administered. This suggests that these states may not only be approaching or have reached their tipping points, they have done so at relatively low levels of vaccine coverage.

The remainder of the states, which fall in between these two extremes, are primarily in the Midwest and, to a lesser extent, the South and West. In about half of these states, between 55% and 60% of adults have received at least once dose. All but one experienced declines in the rate of first doses administered in the last week.

States that demonstrate a combination of low overall vaccination coverage along with slow and declining vaccine uptake raise the greatest concerns. There are the 13 states with less than 50% coverage with at least one dose, all of which are vaccinating their adult populations below the national rate. Twelve of these states also saw declines in the rate at which they were vaccinating adults over the past week. These include 3 states (Alabama, Louisiana, and Mississippi) with vaccination coverage at or below 42%, the lowest in the nation, each of which is vaccinating at about half the rate of the U.S. overall. These are the states that are potentially the greatest distance from reaching sufficient levels of vaccine coverage and might be at risk for future outbreaks if levels are not increased significantly.

Discussion

As with the U.S. overall, most states appear to be at or near their COVID-19 vaccine tipping points – the point at which their supply is outstripping demand.  While this may not be as big a concern for states that have already vaccinated large shares (> 60%) of their adult populations with at least one dose, about one in four states have not yet reached 50%, which is well below coverage levels likely to be needed to drive down the risk of outbreaks going forward. Furthermore, in these states, the pace of vaccination is below the national rate. The fact that most of these states are also seeing declines in the rate of first dose administration suggests that they will be important targets for focused efforts to generate increasing vaccine demand.

Methods

Vaccination data were obtained from Johns Hopkins University Centers for Civic Impact, which collects state-level vaccination data from both the Centers for Disease Control and Prevention (CDC) and state COVID-19 dashboards, and by the Pennsylvania Department of Health (Pennsylvania data do not include the city of Philadelphia). Adult population data (18 years and older) were obtained from the 2019 State Population by Characteristics from the U.S. Census Bureau. We calculated both the 7-day rolling average for first doses administered and the share of the adult population that has received at least one dose for each state and the U.S. overall (excluding territories and doses administered through federal facilities for the U.S. overall calculations). We used these rolling averages to calculate the rate at which states and the U.S. are administering first doses per 100,000 adults. Weekly changes in rates of first doses administered were calculated using the percentage change from the current rate (April 29, 2021) to the rate from 7 days prior. Finally, we categorized states by region using the 2010 U.S. Census Bureau Region and Divisions classifications.