State health officials are bracing Minnesotans for a substantial increase in COVID-19 cases, including 463 lab-confirmed cases reported Wednesday morning, as testing increases for the novel coronavirus that causes the infectious disease.

Eighteen new deaths were reported as well, bringing the toll of the pandemic to 319 fatalities. One of the newly reported deaths involved a 30-year-old, the youngest victim in the state so far of COVID-19 that has been harshest on the elderly and residents of long-term care facilities.

The state has reported 4,644 COVID-19 cases since the start of the pandemic, based on 66,744 molecular diagnostic tests — including a single-day high of 2,915 tests reported on Wednesday.

While the coronavirus is clearly spreading, the rising count is due to increased testing that is identifying more previously unknown cases and finding a high prevalence of cases in nursing homes and meatpacking plants with known outbreaks, said Kris Ehresmann, state infectious disease director.

“With more testing we will see more cases,” said Ehresmann in a media briefing on Tuesday. “I want to lay that out — that in the next number of days, we are going to continue to see more and more cases, and people should not be shocked or concerned.”

Gov. Tim Walz was scheduled later today to join U.S. Rep. Collin Peterson, D-Minn., in Worthington to discuss the outbreaks in food processing facilities, including the JBS pork plant that has temporarily shut down. That outbreak has fueled the 616 lab-confirmed cases in surrounding Nobles County.

Walz also later this week must decide whether to extend or amend the statewide stay-at-home order, which will expire May 4. The governor in statements over the past week has hinted that he will “dial” back restrictions, but that some might still be needed to limit the spread of the outbreak. Certain retail and other businesses with high and unpredictable levels of foot traffic — which can allow infected people to spread the virus to others — could remain closed.

Increased testing has been a key part of the governor’s strategy for managing the outbreak after the end of the stay-at-home order, which was designed to reduce face-to-face contact and disease transmission by up to 80% and to delay the pandemic so that hospitals had time to prepare.

Other preparations included the identification of about a dozen alternate care sites that could treat routine hospital patients in the event that acute care hospitals were overwhelmed with COVID-19 cases. On Wednesday, Walz announced a lease of the Presbyterian Homes-Langton Shores in Roseville to serve as one of those sites.

“By setting up this alternate care site in Roseville, our team is making sure that — should it ever be needed — our hospitals have the capacity they need to treat all patients who need care,” Walz said in a statement.

The state might not reach his goal by Monday of 5,000 molecular diagnostic tests per day, as state Health Commissioner Jan Malcolm said there have been delays in setting up a coordinated statewide testing strategy and getting supplies to the right locations.

Testing is not “ramping up quite as quickly as I had hoped,” Malcolm said on Tuesday, though the state is still on track to reach a capacity of up to 20,000 tests per day under a $36 million partnership with the University of Minnesota and Mayo Clinic.

The partnership will add thousands of serological blood tests as well that can detect the presence of antibodies in people who have recovered from COVID-19. However, the World Health Organization recently announced that there is no proof yet that having antibodies implies that people are now immune.

The antibody tests for now will help to define the breadth of the outbreak in Minnesota, but can’t yet be used to identify people who are no longer infectious, or who can work and move about without restrictions, said Dr. Ruth Lynfield, state epidemiologist.

“It may not be the case that it will have lifelong immunity, but I am hopeful that there will be immunity for a period of time,” she said. “But this is something that we really have to be very careful about.”