Pfizer and its partner company said this week that they’re launching a clinical trial to see if their COVID-19 vaccine is safe and effective for pregnant women. The phase 2/3 study will test approximately 4,000 healthy, pregnant women 18 years of age or older, according to Pfizer and BioNTech. The women will get the shot between 24 to 34 weeks of gestation in the randomized, placebo-controlled, observer-blind trial. Pfizer’s mRNA vaccine requires two doses spaced apart approximately 21 days. Some of the women will get the two doses; others will get a placebo administered three weeks apart. Volunteers will be drawn from multiple countries, including the United States, Argentina, and South Africa. “We are proud to start this study in pregnant women and continue to gather the evidence on safety and efficacy to potentially support the use of the vaccine by important subpopulations,” Dr. William Gruber senior vice president of …