Pfizer and its German partner on Monday said they plan to file for expanded approval from U.S. regulators for their COVID-19 vaccine after a new study indicated the shot remains effective for over four months. Vaccinated children 12 to 15 saw 100 percent effectiveness against COVID-19 in an ongoing clinical trial, Pfizer and BioNTech said in a statement. That conclusion was drawn from measurements taken seven days through over four months after the second dose of the two-dose regimen. Data from 2,228 participants were analyzed. Thirty COVID-19 cases were detected but all 30 patients received a placebo, not the vaccine, according to the companies. The data have not been peer-reviewed and much of it has not been made public. There are plans to submit them for scientific peer review “for potential publication,” Pfizer and BioNTech said. The companies also said the safety data was “generally consistent” with other safety data …