Tennessee now ranks near the bottom of all states in percentage of residents who have received their first dose of COVID-19 vaccine after weather delays and a series of vaccine handling mishaps at the Shelby County Health Department.

Tennessee has administered first-round vaccine doses to 11.2% of its population, trailing every state and territory except for Utah, Puerto Rico and the Virgin Islands, according to tracking from The Washington Post.

Nationally, 13.4% of the population has received an initial dose of vaccine.

An investigation by the Tennessee Department of Health over the weekend found seven incidents throughout February where unused vaccines at the Shelby County Health Department were left to expire, amounting to more than 2,400 wasted doses.

In addition, the state found 51,000 doses of COVID-19 vaccine in the Shelby County Health Department's inventory.

Tennessee Health Commissioner Dr. Lisa Piercey said during a news briefing Tuesday that it would be appropriate for Shelby County — the state's most populous county — to have about 21,000 doses in inventory. That means Shelby County was sitting on an excess of about 30,000 vaccine doses.

The state attributes the county's failures to a lack of standard operating procedures for vaccine storage and handling, insufficient record keeping and absence of a formal process for managing soon-to-expire doses.

"I can't ignore the fact that our largest population center, and the issues that we've been describing today with inefficiency, are kind of pulling down the whole state's average," Piercey said, adding that department of health personnel are now addressing the issues.

"The people of Shelby County deserve efficient and effective vaccinations," she said.

Piercey said the number of overall doses administered in the state is still relatively in line with Tennessee's population.

"If you look at our numbers, the second dose population is pretty robust. That is a product of us having very early success — we had so many first doses delivered very quickly," she said.

(READ MORE: Pace of COVID-19 vaccinations in Chattanooga region ramping up as confusion, demand continue)

Other factors contributing to Tennessee's vaccine slowdown include weather and the state's emphasis on second-dose vaccinations.

Two winter storms in February that heavily impacted the middle and western areas of the state caused numerous shipping delays and forced many health departments to postpone or temporarily suspend vaccination efforts.

In addition, the state has prioritized second doses by guaranteeing that every Tennesseean who receives a first vaccine dose will get a second.

Piercey said Tennessee prioritizes second doses because that's providing full protection to the most vulnerable populations who were eligible first.

Tennessee exceeds the national average for 75-plus-year-old vaccinations by 25%, she said.

"I'm really proud to say that 57% of all Tennesseans age 75 plus have been vaccinated," Piercey said. "That is the population that is driving our hospitalizations and deaths."

Contact Elizabeth Fite at or follow her on Twitter @ecfite.