Johnson & Johnson on Tuesday asked the Food and Drug Administration (FDA) to authorize a second shot of its COVID-19 vaccine. The New Jersey-based company officially asked for an expansion of the emergency use authorization that U.S. regulators granted in late February for the single-shot vaccine. Johnson & Johnson says analysis of U.S. insurance claims show the vaccine proved effective in preventing infection and hospitalization but that clinical trial data revealed a second shot boosted that protection. The vaccine was 81 percent effective in preventing infections, according to the claims analysis, while a second shot increased protection against moderate to severe disease to 94 percent, according to the trial data. “Our clinical program has found that a booster of our COVID-19 vaccine increases levels of protection for those who have received our single-shot vaccine to 94 percent. We look forward to our discussions with the FDA and other health authorities …