NEW MEXICO (KRQE) – The state keeps a close eye on different models and statistics to decide things like when to reopen schools and businesses. But this particular virus presents some unique challenges in tracking some of that data.

New Mexico has its own Gating Criteria for safely reopening. Two of the factors the state is keeping a close eye on are ‘rate of spread‘ and test positivity rate.

“With case counts coming down, our test positivity rate is coming back down too,” said Human Services Secretary Dr. David Scrase, during an August 6 news conference. “Our target is five {percent} but I think we all feel, got more comfortable, and I know the governor feels more comfortable if we’re below four, and now we’re down to 3.5. That’s good news.”

Dr. Scrase was referring to the percentage of positive tests based on the number of tests administered. In a July 30 news conference, the state showed a seven-day rolling average graph for the state’s positivity rate. It showed overall, New Mexico’s positivity rate is better than much of the nation’s.

However, that number also varies by location. In Bernalillo County, for example, much more testing is being done than smaller counties like Lea or Union, where positivity rates can be much higher.

New Mexico is also looking at the virus ‘spread rate’ which is a formula used to determine how many secondary infections are caused by an initial infection. New Mexico has a target spread rate of 1.05 or less, and the state has stayed below that target over the last couple of weeks.

Mathematical epidemiologists with Los Alamos National Laboratory say the fact that there are so many asymptomatic carriers of this virus, make for unique challenges. “That of course makes it challenging to track people who might be spreading it, and to understand how many total infections we have,” explained Carrie Manore, Mathematical Epidemiologist for LANL.

“What we do to try to minimize uncertainty is we consider a range of possible values for those asymptomatic folks to try to understand how important that factor is in our model outcomes,” Manore added.

The team at LANL is working with local and federal partners to help track COVID-19 data. Manore and her team said it’s important to look at multiple models to get the best picture of where the state stands with the virus.

“If you’re looking at one model you might not be getting the whole picture,” explained Sara Del Valle, Deputy Group Leader for LANL. “But when you’re looking at a compilation of models and all of them agree, it seems like the state is probably doing the best that it can do,” she added.

Another challenging factor in forecasting COVID-19 models is human behavior, Del Valle explained. “In our models, we estimate a compliance level in terms of social distancing, face mask usage, hygiene, and if people are not really complying, then that’s very difficult,” she explained.

During the governor’s August 6 news conference, Katrina Hotrum-Lopez with the state’s Aging and Long-term Services Department said they’ll now factor in county positivity rates to determine whether to allow socially distanced visits in longterm care facilities. According to the state Department of Health data, 21 counties in the state currently have a test positivity rate under 5%.