LAS VEGAS (KLAS) — Nevada has hit a milestone with 500,000 vaccines distributed, but the state continues to lag behind others in terms of the number of doses it’s receiving each week per capita.

Out of all 50 states and the District of Columbia, Nevada ranked No. 46 in terms of vaccine doses delivered per 100,000 people and No. 42 for doses administered as of Friday, according to the Centers for Disease Control.

The 500,000 milestone includes first and second doses statewide. In Clark County, more than 300,000 doses had been administered by Tuesday, the last day the Southern Nevada Health District provided data. Nearly 65,000 Clark County residents had received both doses so far as of mid-week.

“Our goal here and what we really have to focus on here in Nevada is to be able to use what we receive,” Candace McDaniel, of Nevada DHHS, said. “I feel like we’ve made wonderful gains and been able to scale up operations very much to the credit to our vaccinators who are on the ground.”

Nearly 300 doses have been discarded, according to the health district, though specifics about why were not provided. A note from the health district reads the doses could have been “lost during training purposes,” expired or contaminated.

“The Southern Nevada Health District works with its staff and partners to ensure COVID-19 vaccine is handled efficiently and to minimize doses having to be discarded,” a spokeswoman said in an email. “The recent increase in the number of discarded doses reported by the health district was found to be due to errors including vaccine being overdrawn and doses set to expire not being used first at clinics. The health district has addressed both these issues with all partner clinics and staff, and they have been corrected.”

Severe winter weather has caused a backlog of 6 million COVID-19 vaccine doses, a White House official announced Friday.

White House coronavirus adviser Andy Slavitt said vaccine delivery to all 50 states has been impacted by the storms that covered roads with ice and snow and led utilities to use rolling blackouts to ease strained power grids.

The Department of Health and Human Services also issued a bulletin, advising recent vaccine recipients about quarantine protocols.

“It is important that all vaccinated persons continue to follow current mitigation measures to protect themselves and others, including wearing a facemask, social distancing, avoiding crowds, avoiding poorly ventilated spaces, properly covering coughs and sneezes, washing hands often, following the Centers for Disease Control and Prevention (CDC) travel guidance, and adhering to any workplace or school guidance,” the bulletin said.

“Persons who have been fully vaccinated and subsequently exposed to someone with suspected or confirmed COVID-19 are not required to quarantine” if they are two weeks past their second dose or are asymptomatic since COVID-19 exposure, the bulletin said.