As hospitalizations for COVID-19 have risen in recent weeks, state officials have noticed an increase in the number of fully vaccinated individuals being admitted.

During a media briefing this week, Maine Center for Disease Control and Prevention director Dr. Nirav Shah said 70 to 75 percent of people currently hospitalized with COVID-19 are unvaccinated, which is a bit lower than the 80 percent or more from a few weeks ago.

That means as many as one in four hospitalized COVID-19 patients are so-called breakthrough cases, or people who have contracted the virus even though they are fully vaccinated.

Shah said that breakthrough cases, as well as related hospitalizations, were “predicted and predictable.” He said they remain a “rarity” and should not be cause for alarm.

“Although they are concerning to many out there, I’ll be straight with you: They’re not what’s keeping me up at night,” he said.

Josh Michaud, associate director for Global Health Policy at the Kaiser Family Foundation, agreed that breakthrough cases should not be considered a major concern, nor should they be used as a reason to say the vaccines are not working.

“The bottom line with the vaccines we have is that they are very effective at preventing severe disease, hospitalization and death, and that includes from the delta variant,” he said. “Does that mean they are an invulnerable shield? Of course not.”

There is overwhelming data that suggest the risk of being hospitalized or dying from COVID-19 is dramatically lower among vaccinated individuals.

A recent U.S. CDC study found that unvaccinated people are 29 times more likely to end up hospitalized from COVID-19.

Still, because the vaccines by Pfizer, Moderna and Johnson & Johnson range in efficacy from 75 to 90 percent, some breakthrough cases are going to occur.

In fact, breakthrough cases are more common in a place like Maine, which has a high rate of vaccination.

“A small percentage of a larger number can still be a large number,” Michaud said.

Added Shah: “Even though there are more breakthrough cases, you would still rather live in a community where 90 percent of the people are vaccinated rather than 30 percent, even though you’re going to have fewer breakthrough cases in the 30 percent.”

According to the most recent data tracked by the Maine CDC, as of Aug. 13 there have been 863 breakthrough cases out of nearly 38,000 total positive cases since vaccines became available. Although the number might be slightly higher because the state can’t investigate all cases to determine vaccination status, breakthrough cases represent about 2 percent of all cases.

Another way to look at the numbers is this: As of Thursday, 838,161 Maine residents are fully vaccinated. That means 0.1 percent of those people have been infected.

Thirty-five of the 852 hospitalizations since vaccines have been available are confirmed to be in people who were fully vaccinated – about 4 percent. And among the 237 deaths reported since vaccinations began, 14 have been people who are fully vaccinated. That’s just under 6 percent.

In virtually all cases of breakthrough deaths and hospitalizations to date, Shah said, the individual had other serious health conditions that contributed.

The next update on breakthrough cases is scheduled for Friday, CDC spokesman Robert Long said.

“The recent surge in cases has led Maine CDC to change the way breakthrough cases are tracked and reported to make best use of available resources,” he said.

During a conference call with reporters Thursday, hospital officials reiterated the point that although vaccinated individuals can be hospitalized, that is not the norm.

“When we look at Northern Light, 90-plus percent who are admitted are unvaccinated,” said Dr. James Jarvis, COVID-19 incident commander for the health care network. “And the sickest cases are those who are not vaccinated.”

Dr. Joan Boomsma, chief medical officer for MaineHealth, said closer to 80 percent of their hospitalized patients – and all of their ICU patients – are unvaccinated.

“I’m not surprised given the high percentage of vaccinated people in the state that there will be some who have symptoms, but far and away they are not the sickest people we’re seeing,” she said. “This surge is being driven by pockets of unvaccinated people.”

Maine is one of 24 states that still tracks breakthrough cases. The U.S. CDC had been tracking them this spring but stopped in May. Now, the federal agency tracks only breakthrough cases that lead to hospitalization or death.

As of Aug. 16, the U.S. CDC reported 9,716 patients across the country who were hospitalized or died from COVID-19 after being fully vaccinated. That’s among 168 million who are fully vaccinated.

Many have acknowledged that this data is likely incomplete because it relies on states and hospital systems to voluntarily report it.

Kaiser recently analyzed breakthrough cases for states that still track them, including Maine. It found that the percentage of breakthrough cases ranged from 5.9 percent in Arizona to 0.2 percent in Connecticut.

Of the states that track deaths among fully vaccinated people, the rates are also extremely low. In Washington state, 48 of 2,249 people (2.1 percent) who have died since vaccines were available have been fully vaccinated. In Michigan, 217 of 8,078 deaths (2.6 percent) have been among fully vaccinated individuals. And in Arizona, 92 of 9,232 (0.9 percent) deaths have been in breakthrough cases.

The rate of deaths in Maine is likely higher because the actual numbers here are smaller.

Politico reported this week that the U.S. CDC is hampered by outdated and unreliable data on breakthrough infections. One of the biggest reasons they are tracked is to help experts determine if vaccine immunity might be waning.

“I think we are hampered by the fact that we don’t have robust surveillance,” said Michaud, at Kaiser.

Health officials already have begun planning for booster shots as early as next month.

Either way, Michaud said, panic over breakthrough cases can and is being used by some to further anti-vaccine sentiment.

“People are using this evidence to further their already set beliefs about the vaccine,” he said. “People are saying: ‘Why get the vaccine if they can result in breakthrough cases?’ That completely ignores all the data we have about the protection from the vaccines, not just from getting infected but from becoming seriously ill.”

Although breakthrough cases are not a major cause for concern, health officials have said there are still measures people can take to avoid them, including wearing a mask indoors in areas of high transmission or around people who might be immunocompromised or unvaccinated, including children.

“Overall, if you’re concerned about landing in the hospital with COVID-19, which is a risk, the single best thing you can do today is to go get vaccinated,” Shah said.