Minnesota health officials say more than half of state residents who tested positive for COVID-19 in December were vaccinated.

Roughly a third of those who were hospitalized for COVID-19 or died during that month also were vaccinated.

The Minnesota Department of Heath breakthrough case data does not indicate if people had received booster shots.  Health officials say the omicron variant was a big part of the growth in breakthrough infections.

Nevertheless, health officials say vaccines along with a booster dose remain the best way to protect against severe illness and to slow the spread of the coronavirus.