The US government expects to secure 600M coronavirus vaccine doses by the end of July, enough to inoculate 300M Americans according to remarks from President Biden at the National Institutes of Health yesterday. The vaccines include an additional 200M doses from Pfizer and Moderna.
More context: A distribution timeline for the newly-secured vaccines has not yet been released. To date, nearly 35M people have received at least one vaccine dose and 11M people have received two doses (source).
Extra: The announcement comes amid a decline in newly reported cases in the US, with the trailing 7-day average dropping by over 20% in the last week and 59% from peaks in January.