By Bret Kenwell Johnson & Johnson affirmed its full-year outlook and announced a new $5 billion buyback. Should you be a buyer right now? Johnson & Johnson (JNJ) – Get Johnson & Johnson Report stock has not been immune to the recent stock market selloff, although it’s held up better than the S&P 500. So far on the year, Johnson & Johnson stock is down 4%. That’s better than the 16.5% drop in the S&P 500. Of course, today’s action is helping, as J&J stock is about 2.5% higher at last check. The move comes after the health-care giant announced a $5 billion buyback plan and affirmed its full-year…