https://www.cnbc.com/2021/08/05/moderna-covid-vaccine-booste... has some details released by Moderna this morning. Important bit:

In a phase two trial, Moderna is testing a 50-microgram dose of three vaccine booster candidates in previously vaccinated individuals. The booster shots produced a promising immune response against three variants, including delta, with antibody levels approaching those seen in previously unvaccinated people who received two 100-microgram doses, the company said.

I'm interested to know if just getting another dose of the original vaccine has any effect. If so, I'd love to get it now.

Both Pfizer and Moderna have stated that boosters will be needed this Fall. Pfizer says that immunity drops from 96% to 84% at the six month point. The good news is that the vaccine continues to protect against severe disease due to its effects on T-cells and memory B-cells.