Maine Center for Disease Control and Prevention Director Nirav Shah speaks at his final, regular pandemic press briefing in Augusta on June 30, 2021. Credit: Troy R. Bennett / BDN

A quarter of the people hospitalized with COVID-19 in Maine have been fully vaccinated, with a top public health official tying a recent rise in still exceedingly rare breakthrough cases on Monday to a growing number of inoculations and a more contagious variant.

Maine Center for Disease Control and Prevention Director Nirav Shah said during a Maine Public interview that the number of people hospitalized with the virus stood at 42. Roughly 25 percent of those are breakthrough cases in a noticeable increase from just a few weeks ago, when more than 90 percent of people hospitalized with the virus here were not fully vaccinated.

It’s an example of the challenges posed by the rising delta variant, but vaccines are still proving virtually 100 percent effective at preventing serious cases. The 29 Mainers hospitalized to date with breakthrough cases only account for 1 in every 30,000 of inoculated people here. Not accounting for age differences, unvaccinated people are still more than five times as likely to be hospitalized with COVID-19 in Maine right now compared with vaccinated people.

The rise in serious breakthrough cases was concerning to Shah, but he still emphasized that the risk of getting one is “very, very, very small” and that such events should be expected as more people get vaccinated and the more contagious delta variant circulates.

“Make no mistake, if you haven’t been vaccinated, your likelihood of landing in the hospital if you get COVID is high, especially with the delta variant,” Shah said.

Hospitalizations in Maine have remained relatively low even as the delta variant has become more prevalent. The variant is estimated to have made up 60 percent of positive cases seen in Maine in July, but the exact figure is not known because the state only screens a sample of positive tests for it.

The increase highlights the urgency of getting more people vaccinated as rates have decreased in recent months. As of Monday, about 854,000 people, or 72 percent, of the population have been vaccinated, Shah said. The data on breakthrough cases is roughly in line with 15 other states that have reported on them, according to the Kaiser Family Foundation.

BDN writer Jessica Piper contributed to this report.

Correction: A previous version of this story misstated how many fully vaccinated people have been hospitalized with the coronavirus. The error was made based on information Maine Center for Disease Control and Prevention Nirav Shah provided during a Maine Calling interview and was corrected by his agency.