Health and medical groups around the country are bracing for another grievous blow to America’s infrastructure of evidence-based health, this time targeting preventive medicine.

Earlier this week, health secretary and ardent anti-vaccine activist Robert F. Kennedy Jr. abruptly canceled a meeting of the United States Preventive Services Task Force (USPSTF), a scientifically independent panel of up to 16 volunteer experts that issues rigorous, evidence-based recommendations on preventive care—on everything from colonoscopies to folic acid supplements in pregnancy. The panel uses a highly transparent and rigorous framework, grading recommendations on an A to D scale. Recommendations with an A or B grade are adopted nationwide, and health insurance plans are required to cover them at no cost to patients.