By Tim Mastro

WILMINGTON — Eighty-eight percent of Delaware’s positive COVID-19 cases for the week of Jan. 3-9 occurred in people who have not received a booster dose of vaccine, Delaware Division of Public Health director Dr. Karyl Rattay said in a press conference Tuesday.

For the same time frame, the most recent available dataset, 91.4% of new COVID-19 hospitalizations were not boosted.

“We’re clearly seeing the importance of this with the omicron variant,” Dr. Rattay said. “We need to double down on the number of Delawareans who have received their primary series and their booster.”

Dr. Rattay explained the current vaccines and boosters target a spike protein on the COVID-19 virus.

The omicron variant, which accounted for 93% of Delaware’s confirmed variant cases last week, has many mutations which helps it evade antibodies generated by prior infection or two doses of vaccine.

She said the antibodies from the vaccine and prior infection offered more protection against the delta variant, which is down to 7% of variant cases in the state. But the state is seeing that is less the case for people fully vaccinated or who’ve been previously infected as it relates to preventing omicron infection.

Boosters have aided in protecting against omicron as Moderna’s booster increased antibody levels against omicron by 37 times while Pfizer’s booster increased levels by 25 times, Dr. Rattay said.

“Fully vaccinated still protects against severe illness, but the boosters are much more likely to block the infection,” she said, “which is important for many reasons including for prevention of future genetic mutations.”

Only about 30% of Delawareans 12 years old and up have received their booster, Dr. Rattay said.

Delaware’s COVID-19 statistics have leveled off slightly after peaking last week. The number of individuals hospitalized has declined each of the last five days and is down to 683 — the lowest number in the last 12 days. That is still more than 200 higher than last year’s peak of 474.

Delaware is averaging 2,514.9 new cases per day over the last seven days.

“Our case rates and our hospital rates remain extremely high,” Dr. Rattay said. “This is not the time to let our guard down.”

Dr. Rattay said the state is seeing good compliance from the recent indoor mask mandate which went into effect last Tuesday. She added mask enforcement will occur through local law enforcement instead of DPH like it did last year, due to DPH focusing on its vaccination and testing programs.

“We said we wouldn’t enforce it with a heavy hand,” Gov. John Carney said. “We were going to call for folks to comply with the mandate and hope they will. Frankly the compliance I’ve observed, obviously anecdotal, has shown a real difference in public spaces. You can see the difference as you circulate. ... It also creates a great awareness that this is a serious situation.”

Updated COVID-19 statistics were unavailable Tuesday due to DPH reporting delays.