"It is right to be contented with what we have, but never with what we are."
yes and no. yes it's also an injectable contraceptive, but the mechanism and the user experience would be very very different. Since depo is hormonal, there are ongoing side effects for many women which can affect libido, weight, mood, headaches... and its been linked to osteoporosis, so long term use is not generally advisable. Plus you have to get the shot every three months. And if you get it immediately post-partum it can wreck your milk supply.
A vaccine would theoretically be a couple, three shots that then provided long-term contraception without much need for follow up. Since it wouldn't work through a hormonal modality, the only side effects would be those of vaccination - generally pain at the injection site and possible flu-like feelings for a day while your immune system digests it.
If the vaccine were effective, it would be very cool. BUT since it wouldn't likely be easily reversible, nor as long-term dependable as a surgical procedure, my bet is with further development of Essure type technology instead for permanent sterilization.