Only 2.5 percent of Missourians who received their first COVID-19 vaccine dose skipped out on receiving the second one, according to a study released Monday by the Centers for Disease Control and Prevention that looked at a two-month period.
Out of the 50 states, Missouri had the 10th highest rate of completion of the vaccination series, with 93 percent of over 216,000 residents receiving their second dose. Other states completion rates ranged from nearly 96 percent in West Virginia to roughly 75 percent in Utah.
Meanwhile, 2.5 percent of people who had received their first dose in Missouri had not received their second dose within the recommended six weeks — which was better than the national average of 3.4 percent. Virginia had the highest percentage of residents who had missed their second dose at 7.8 percent, while Louisiana had the lowest at nearly 1 percent.
For Missouri, about 4.5 percent had not yet received their second dose as of the analysis but still remained in the allowable period of six weeks. Of those who had received their second dose, nearly 97 percent received it in the recommended timeframe.
The CDC’s study, the first federal analysis to look at completion of the two-dose vaccine series, found that nationwide among people who had received the prime dose, 88 percent received their booster dose, 3.4 percent had missed their second dose and 8.6 percent had not yet gotten it but were still within the allowable interval to receive it.
The study assessed nearly 12.5 million people who had received a first dose and for whom sufficient time had elapsed to receive their second dose between a two-month period from Dec. 14 to Feb. 14.
Both Pfizer and Moderna’s vaccines require two shots, spaced out three and four weeks respectively. The CDC also recently issued guidance that said booster doses may be given up to six weeks after the initial shot if those intervals can’t be met.
Winter weather delays during that time that led to canceled appointments and delayed doses — which affected Missouri — may have contributed to lower rates in some areas, according to the study.
Overall, the study noted the findings were reassuring, as they showed nearly 9 out of every 10 people who received the first dose ended up getting their second.
However, it also stressed that groups prioritized early on to receive the vaccine in many states — like healthcare workers and nursing home residents and staff — were more likely to be vaccinated at their work or home, which may have led to increased adherence of the recommended vaccination schedule.
“As priority groups broaden, adherence to the recommended dosing interval might decrease,” the study noted.
On Monday, another 550,000 Missourians are estimated to now be eligible to receive the vaccine with the activation of Tier 3 of Phase 1B. The tier includes many workers essential to critical infrastructure, like teachers, grocery store employees and childcare providers.
An analysis last month by the Missouri Hospital Association had found that through March 1, 56,720 Missourians had not received their booster dose between the prescribed timeframe of 21 to 28 days, which accounted for about 6.5 percent of all individuals who had been vaccinated in the state.
Among those, a much smaller portion of 1,817 individuals were beyond the most recent CDC guidance that recommended booster doses be administered within 42 days.
The CDC study found that among racial groups, American Indian and Alaska Natives had the lowest rate of series completion nationwide at 83.7 percent and the highest rate of missing the booster dose at 5.1 percent.
The study noted one limitation to the data included people being counted twice if they had received their doses from two different entities or if their first and second dose had not been linked during reporting. This may have contributed to lower rates for American Indian and Alaska Natives as tribal nations often border multiple jurisdictions, the study said.
In addition, assessing differences in vaccination completion by race was limited by the fact that racial data was missing for nearly 46 percent of people.
The Missouri Hospital Association’s analysis also could not evaluate booster dose completion rates along demographic lines due to high frequencies of missing racial data in the state’s database.
However, the analysis found that “a near-monotonic relationship” exists between the poverty level of a recipient’s ZIP code and the percent of recipients overdue for the booster dose.
Higher poverty rates saw higher percentages of residents missing a second dose.
The analysis pointed to the single-dose Johnson & Johnson vaccine as potentially “an effective strategy in fully protecting socially vulnerable populations.”