The Navajo Nation, which inhabits the largest area of land retained by an indigenous tribe in the United States, reported Monday that it had zero new coronavirus cases and deaths in the previous 24 hours after rolling out an aggressive vaccination campaign.

The tribe, whose land stretches across Utah, Arizona and New Mexico, had the highest per capita infection rate in the U.S. at the height of the pandemic.

The last time the tribe reported zero new cases was on Sept. 8, when four people died from Covid-19. That hope was short-lived, as cases spiked again after Labor Day, with up to 400 new daily cases reported around November.

“Zero deaths and zero cases in 24 hours — yes, it’s remarkable,” Navajo Nation President Jonathan Nez said during a town hall meeting Tuesday. “But let’s not let that get to our heads. This is not the time to be traveling.”

The numbers started diminishing as Pfizer and Moderna rolled out Covid-19 vaccines throughout the Navajo Nation and the rest of the U.S. after the drugmakers won emergency approval from the Food and Drug Administration in mid-December.

As of Tuesday, 57% of Navajo citizens have received at least one dose of the coronavirus vaccine, and 38% have been fully vaccinated with both doses. Vaccines are available to anyone age 16 and older in the tribe. There are roughly 298,000 enrolled members of the Navajo Nation, with about 173,000 Navajos living on the reservation, according to the University of Arizona.

The tribe also still has a mask mandate and daily curfew in effect, and health officials are also still offering free masks and hand sanitizers to citizens.

It recorded 49 new cases in the last seven days and is averaging 285 tests per day, according to tribal health officials. A former hotspot in the U.S., the tribe now ranks second-to-lowest in new cases per 100,000 citizens in the last seven days in the U.S., sandwiched between Puerto Rico at third and Hawaii at the lowest.

Tribal health officials said the Navajo Nation has been in code orange for the last three weeks, which means that cases are on a downward trajectory. Its outbreak is contained enough to now fall under code yellow, which would mean that there is no evidence of a sustained rebound of coronavirus cases in the tribe, officials said.

Acting Deputy Area Director Captain Brian Johnson said that five rounds of funding from the U.S. government under the CARES Act, along with Navajo citizen compliance made a significant difference in the tribe’s ability to tackle the pandemic.

Last Monday, some businesses were allowed to reopen at 25% capacity under certain restrictions. Parks and lakes are set to reopen soon to Navajo citizens only. The tribe still isn’t allowing any outside visitors and requires all schooling to be virtual.

“We’re not out of the pandemic yet,” Nez said in addressing the Navajo Nation. “Be strong and resilient as our ancestors have been since time immemorial. … Covid-19 will also be defeated, because we are strong warriors and we have the armor and weapons to fight this modern-day monster.”