RAMSGATE, UNITED KINGDOM - DECEMBER 16: A vial of the Moderna vaccine is seen at an NHS Covid-19 vaccination centre on December 16, 2021 near Ramsgate, United Kingdom. The Government is pushing the booster jab program as the country recorded its highest number of daily infections since the pandemic began. England's chief medical officer Professor Chris Whitty has warned that more Covid records will be broken as the Omicron variant spreads further. (Photo by Leon Neal - WPA Pool/Getty Images)

(AP) – Moderna is asking U.S. regulators to open its COVID-19 vaccine to the nation’s youngest children. Kids under 5 are the only group in the U.S. not yet eligible for vaccination. Frustrated parents are waiting impatiently for a chance to protect them. Moderna submitted data to the Food and Drug Administration Thursday. The company hopes the FDA will rule in time for tots to start getting vaccinated by summer. It’s a complex decision partly because while other countries give Moderna shots to older children, the U.S. so far has restricted them to adults. Rival Pfizer also is studying its vaccine in the littlest kids.