A federal judge in Georgia blocked the Biden administration’s COVID-19 vaccine mandate for contractors on Tuesday, almost exactly three months after Biden issued an executive order requiring shots for workers doing the government’s business.

Most prime contractors at Department of Energy defense-nuclear sites had had their contracts modified to include a vaccine mandate well before Tuesday’s preliminary injunction in the U.S. District Court for the Southern District of Georgia. The injunction blocks enforcement of the vaccine mandate while the court case proceeds.

Several DoE defense-nuclear sites that report vaccination data have reported vaccination rates much higher than the national average. The National Nuclear Security Administration’s (NNSA) nuclear weapons laboratories all claimed vaccination rates of 90% or more, as of Wednesday morning. At the NNSA’s two main production sites, Y-12 and Pantex, thousands of workers became fully vaccinated between Sept. 10, a day after Biden’s order, and last week.

At DoE nuclear sites, deadlines to get vaccinated or get fired, unless exempted from the now-enjoined mandate for religious or medical reasons, ranged from Nov. 30 to Jan. 18. The Biden administration’s Safer Federal Worker Task Force moved the deadline to Jan. 18 from Dec. 8 on Nov. 4.

Though it is the exception and not the rule, contractors can and have adopted their own vaccine mandates. Triad National Security, the NNSA’s operations contractor for the Los Alamos National Laboratory, put a vaccine mandate in place in August, before Biden’s executive order came down. That mandate has so far survived court challenges.