Most people with allergic reactions to the first dose of an mRNA COVID-19 vaccine from either Pfizer/BioNTech or Moderna can safely receive the second dose, a new study shows. The rates of allergic reactions to these vaccines have been reported to be as high as 2%, with anaphylaxis, the most serious kind, occurring in up to 2.5 of every 10,000 vaccine recipients, the researchers said. They reviewed data on 189 adults with first-dose reactions to one of these vaccines, such as flushing, dizziness or lightheadedness, tingling, throat tightness, hives, and wheezing or shortness of breath. Most of these adults -...