Pfizer’s COVID-19 vaccine was not effective in preventing infection among children aged 5 to 11, according to a new study. Researchers in New York also found indications that the vaccine effectiveness against severe disease plummeted. The researchers, with the New York State Department of Health and the University at Albany School of Public Health, examined outcomes among children using three state databases, including two systems that collect vaccination data. They assessed two outcomes: COVID-19 cases and COVID-19 hospital admissions, regardless of whether the patients were admitted for other reasons. Crunching the data, the researchers found Pfizer’s vaccine dropped from 68 percent in mid-December 2021 to just 12 percent in the last full week in January. The data also suggested the protection against severe disease plummeted, from 100 percent in mid-December to 48 percent in late January. “In the Omicron era, the effectiveness against cases of BNT162b2 declined rapidly for children, …