The prevalence of the highly contagious delta variant of COVID-19 in Maine is likely far higher than official statistics suggest, according to data from new tests of hospital patient screening samples.

And the presence of the variant likely explains a dramatic recent increase in the proportion of COVID-infected patients requiring intensive care.

MaineHealth, the state’s largest hospital network and parent to Maine Medical Center in Portland, began testing certain nasal swab samples from COVID-positive patients July 1 using a new test that can detect the delta variant, a virulent form of the disease first detected in India whose rapid spread forced the United Kingdom, Australia and other countries into fresh lockdowns last month.

The test is expensive and its ingredients are in short supply, so MaineHealth has tested only 49 samples from screened patients who had perplexing characteristics, like very sick young people or fully vaccinated people who found – usually to their surprise – that they were infected. Eighteen of them – 36.7 percent – tested positive for the delta variant, MaineHealth’s chief health improvement officer, Dr. Dora Anne Mills, said Friday.

This is worrisome because the official statewide tally for confirmed delta variant patients is just four, though the latest data cover only tests through June 18, nearly four weeks ago. That means in just over a week, a handful of tests revealed more than four times as many delta cases as this official count.

“Maine CDC expects to see a greater impact of the Delta variant in the state in the coming weeks,” Dr. Nirav Shah, director of the Maine Center for Disease Control and Prevention, said via email. “While Maine’s high vaccination rate limits routes of transmission, the Delta variant is opportunistic.

“Vaccination remains the best way for Maine people to protect themselves from the Delta variant and other forms of COVID-19, as our partners at Maine hospitals tell us that the majority of patients requiring treatment for severe COVID-19 symptoms are not fully vaccinated,” Shah added.

The state’s variant data include only those cases validated by a full DNA sequencing test, a process usually conducted at the The Jackson Laboratory in Bar Harbor. MaineHealth’s tests use a rapid PCR method that, while said to be 95 percent accurate, is considered to yield only preliminary results. Mills said the 18 delta variant-positive samples have been forwarded to the Maine CDC for full sequencing, at which point they would show up in the state’s tally.

The state last updated its COVID variant case numbers on July 2, posting results through June 18. These data suggested a sharp slowdown in the number of samples processed in the first half of June: 67 through the 18th compared to 821 in the month of May.

The long lag time is not unusual for this type of genetic variant testing, which is time-consuming and considered a less urgent priority than regular COVID tests, said Maine CDC spokesman Robert Long via email, noting the U.S. CDC’s latest report on genome sequencing nationally is also dated July 2 and covers data on samples taken through June 19.

“It’s a longer process with less urgency than diagnostic testing,” Long said. “The turnaround time for diagnostic PCR testing, which is a better indicator of transmission risk, has not changed.”

The delta variant has spread at an explosive rate elsewhere in the world. In a few weeks it swept aside the alpha variant to become the dominant strain in the U.K., despite that country’s high vaccination rate.

VARIANTS AND GROWING ICU NUMBERS

The delta variant and its cousins – alpha and gamma – are presumed responsible for a second development that has unfolded over the past three weeks. While hospitalizations for COVID-19 have remained low, the vast majority of those admitted with the disease have been placed in intensive care.

The situation has been particularly acute at the state’s largest hospital, Maine Medical Center, where, as of Thursday, every single COVID inpatient on 16 of the previous 21 days had to be cared for in its ICU. Over the three weeks ending Thursday, Maine Med recorded a total of 210 COVID patient-nights, with 86 percent of them in the ICU.

Across the state Thursday, the majority of inpatients who had tested positive for COVID were in intensive care – 16 of 30. In earlier phases of the pandemic, Maine hospitals typically had only about a third of their COVID patients in intensive care.

The proportion of patients who entered the hospital because of COVID symptoms and needed intensive care is likely even higher, according to Dr. Mills, who is a former Maine CDC director. That’s because some of the patients who are not in intensive care are hospitalized for other reasons but are counted because they tested positive for the virus.

Many of the COVID-positive inpatients her 10-member hospital network had reported in recent weeks are vaccinated people who went to the hospital because of an accident or other unrelated condition and were found to have low levels of the virus when their routine screening results came back, Mills said.

“They’re here for something else and we happen to catch them because we screen everyone who is admitted,” Mills said. “These are typically people who have low levels of the virus, no symptoms, and probably can’t transmit it very effectively.”

The ones entering for COVID are usually very sick, Mills said, and the virulent new variants are to blame. “They’re trending younger and from rural areas and the vast majority are unvaccinated,” said Mills, who is Gov. Janet Mills’ sister. “We just weren’t admitting people in their 20s and 30s and 40s a year ago.”

Despite the presence of the variants, COVID inpatient numbers have been very small at most of Maine’s hospitals in recent weeks.

Over the past three weeks, Southern Maine Health Care Medical Center in Biddeford has had a total of 44 COVID inpatient days, for instance, with 19 in intensive care. The 10-hospital Northern Light Health system has been caring for only three to six COVID inpatients a day during this period, but clinicians there say the majority have been in intensive care.

Dr. James Jarvis, Northern Light’s physician incident commander, said it was difficult to draw statistically meaningful conclusions for his hospital network when the numbers were so small.

“It’s good news we have small numbers of inpatients, but what stands out today is that they tend to be younger individuals. Their body mass index (a measure of obesity) is lower. And that’s different than what we have seen before.”

Jarvis said Northern Light doesn’t test and track what strain of COVID-19 every patient has, so it had no evidence as to whether the more virulent and contagious variants are to blame.

Mills said she expected there would be more bumps in the road for Maine because of COVID-19, but that the state was in a good position.

“Maine is one of the safest places in the world for COVID, because of our high vaccination rates and because it’s summer now and we’re outdoors,” she said. “There will probably be new chapters and some roller coaster rides, but I’m confident that Maine has seen the worst of the pandemic.”

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