A screen shows Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, during a remote panel titled "COVID 19: What's Next?" at the Davos Agenda 2022, in Cologny near Geneva, Switzerland, on Jan. 17, 2022. Credit: Salvatore Di Nolfi / Keystone via AP

AUGUSTA, Maine – A recent backlog of COVID-19 tests in Maine has highlighted a new challenge: Federal health officials continue to rely on an increasingly irrelevant metric to set critical policies.

The Maine Center for Disease Control and Prevention reported a backlog of 46,000 positive tests last week, with health officials warning that infection levels were higher than daily case numbers reflected. State and federal health officials have increasingly pointed to alternative metrics, such as hospitalization rates, to account for the effects of the virus as the highly contagious omicron variant drives up infections.

Maine’s backlog comes as as health officials, including National Institute of Allergy and Infectious Diseases Director Anthony Fauci, have argued in favor of de-emphasizing case counts in light of the new omicron variant, which is both less severe on average and more likely to evade vaccine protection.

But case counts were relevant last week when Maine officials raised concerns that artificially low case levels due to the backlog were leading the state to get fewer supplies of monoclonal antibodies. The federal formula factors in both raw case counts and hospitalizations. Gov. Janet Mills lobbied for more doses, doubling Maine’s supply of the lifesaving drug this week.

Other public health recommendations also still rely on case counts, including the U.S. CDC’s recommendations on mask-wearing, although that has been virtually irrelevant in Maine since the fall because high infection levels have left them in effect for every county.

While Maine and most other places have always only captured a fraction of positive cases with testing, that share may be smaller now than before, said Dr. Gibson Parrish, an epidemiologist from Yarmouth formerly of the U.S. Centers for Disease Control and Prevention.

He noted that high infection rates posed a challenge for laboratory testing and reporting. Simultaneously, more Mainers have been getting tested with at-home tests that do not get reported, further eroding the value of the counts.

Despite these challenges, Parrish said there continues to be value in the state attempting to keep up with reported cases. While hospitalizations and deaths are more complete measures of severe disease, they tend to be lagging indicators of where the virus is most concentrated.

“You may want to provide resources to particular parts of the state, and the decision as to where to put certain resources may depend on how many cases are appearing,” Parrish said.

Maine’s backlog in cases is the largest disclosed by any state health department in the past few weeks, although other states — including Ohio, Georgia and Wisconsin — have noted delays in reporting tens of thousands of cases recently. The extent of backlogs is not clear until health departments acknowledge them, although Maine’s reporting delays appear to be greater.

Backlogs are not the only factor affecting reported case counts, as overall testing continues to vary widely between states. While the testing rate here is slightly higher than the U.S. average, according to an analysis from Johns Hopkins University, nearby Vermont is administering tests at more than twice Maine’s rate. Vermont reported a surge in cases earlier this month that seems to be waning, although hospitalizations have remained lower than Maine’s over that time.

While Maine is likely undercounting cases compared with Vermont, hospitalizations here — which have been roughly flat for the past two weeks even as omicron now accounts for more than 90 percent of new cases here — give little indication that the virus is going to take off further at this point, said Robert Horsburgh, an epidemiology professor at Boston University.

“If you were doing more testing, you’d see more cases, but you wouldn’t find that many more more symptomatic cases because those highly symptomatic patients come to the hospital,” he said.

Moving forward, the state could look beyond raw case counts or inpatient hospitalizations to try to understand the trends of the virus. Seasonal influenza, Parrish noted, is usually measured by emergency room visits rather than cases, as many people who get the flu never get tested.

Other tools to measure the prevalence of COVID-19 have emerged more recently, including wastewater testing, which has been used in the town of Yarmouth for much of the pandemic and is set to expand to other Maine municipalities in the coming months through a state program. Wastewater measurements can pick up trends relatively quickly and provide some indication of virus levels regardless of testing or reporting backlogs, noted Parrish.

“It very possibly gives a clearer picture of the presence of the virus in a given community than looking at just the case counts,” he said.