How well are COVID-19 vaccines working in Americans who got them? CDC releases new data
A new CDC study shows the Moderna and Pfizer COVID-19 vaccines help prevent infections. ( Brad Horrigan/The Hartford Courant/ TNS0. - Photo by Brad Horrigan | bhorrigan@courant.com/Hartford Courant/TNS

New research provides “strong evidence” that the two-dose Pfizer and Moderna coronavirus vaccines are capable of preventing infections — both those that cause symptoms and those that don’t — in real-world conditions, that is, outside the controlled laboratory settings where the initial clinical trials took place. The study, conducted by the Centers for Disease Control and Prevention, found that risk of coronavirus infection dropped by 90% two weeks after receiving a second, final dose and by 80% two weeks following a single dose among nearly 4,000 health care workers, first responders and othe...