AstraZeneca’s COVID-19 vaccine is 74 percent effective in preventing symptomatic illness, according to data from its U.S. clinical trial published in the New England Journal of Medicine on Wednesday. The phase 3 trial involved more than 32,000 participants in the United States, Peru, and Chile, who either received two doses of the COVID-19 vaccine or a saline injection four weeks apart. However, data was based only on 26,212 participants. The vaccine’s overall effectiveness of 74 percent was slightly lower than the initial analysis of 76 percent reported earlier in March by the drugmaker. But the vaccine was still 100 percent effective against severe or critical disease as no cases were observed in the fully vaccinated group compared to eight in the placebo group. Participants in the vaccinated group experienced more solicited adverse events, which were “mostly mild or moderate and were fewer in number after the second dose,” within 28 …