PIERRE, S.D. (KELO) — When the South Dakota Department of Health says that a patient has recovered from the coronavirus COVID-19, the determination isn’t based on a second test.

Instead, it is a judgment, based on national guidance, that the patient has stopped exhibiting symptoms associated with the respiratory illness.

That’s according to state Health Secretary Kim Malsam-Rysdon and state epidemiologist Joshua Clayton.

Including results announced Tuesday, South Dakota so far had 320 positive cases and 5,948 negative tests. Those include results from the state Public Health Laboratory and various private labs.

Among the the positive cases, there were six deaths and 98 recoveries.

KELOLAND News asked Clayton earlier this week about how recoveries are determined. He said Monday the federal Centers for Disease Control and Prevention put forth a revised standard about three weeks ago.

According to Clayton, the CDC considers a person is recovered if there’s been an absence of fever for at least three days and an improvement in respiratory symptoms, and if the person has been in isolation at least seven days after the symptom first occurred.

Secretary Malsam-Rysdon repeated that list Tuesday during Governor Kristi Noem’s briefing for news reporters.

The CDC has another standard that does involve testing, according to a link on the department’s covid.sd.gov website. South Dakota has restricted availability of COVID-19 testing because of limited supplies of materials, as have other states.

There isn’t a vaccine but research is under way.

KELOLAND News also asked Monday whether a recovered patient can contract COVID-19 again. Clayton said the CDC’s understanding of COVID-19 was still at a very low level overall but individuals are “not expected” to be infected with COVID-19 a second time.

He said some patients in China might have been incorrectly diagnosed the first time. “To my knowledge we’ve not seen that in the United States and we have definitely not seen that in South Dakota,” Clayton said. (A recent CBS News q-and-a suggests this hasn’t been determined.)

According to a current CDC guidance, the virus that causes COVID-19 “is spreading very easily and sustainably between people. Information from the ongoing COVID-19 pandemic suggest that this virus is spreading more efficiently than influenza, but not as efficiently as measles, which is highly contagious.”

CDC guidance on flu says about 8% percent of the U.S. population gets sick from the flu, ranging from 3% to 11% depending on the annual fall-winter period when flu is most prevalent.

In South Dakota, through the week ending March 28, the department reported 14,749 confirmed cases of flu this season. The first cases began in October. The current season’s total includes 542 hospitalizations and 27 deaths.

Flu vaccines are distributed each year and people are encouraged to get new vaccinations each fall. Measles vaccines have been found to be 93 to 97 percent effective in the United States and, for most people, last a lifetime, according to the CDC.