A team at Massachusetts Institute of Technology has designed a new type of micro-particle that could combine everything into a single jab.
The particles look like miniature coffee cups that are filled with vaccine and then sealed with a lid.
Crucially, the design of the cups can be altered so they break down and spill their contents at just the right time.
One set of tests showed the contents could be released at exactly nine, 20 and 41 days after they were injected into mice.
Other particles that last for hundreds of days have also been developed, the researchers say.
The approach has not yet been tested on patients.