Worldwide, the plague never really goes away. Luckily, those of us who served in Southeast Asia were fully vaccinated against it. That fact was a constant source of support and boosted my confidence level enormously.
The vaccine was especially foul-smelling and is something I won’t forget. I hated working with the stuff.
the current - and former - plague vaccine ONLY lasts 6-12 months.
It is still recommended to get boosters every 6-12 months - at least annually - if working in high incidence plague areas.
I too had the series prior to going to SE asia (MIA-POW missions with 25th ID AVN BDE in ‘92 and ‘93 in Cambodia with layovers in Thailand as team physician). Worst reaction ever to a vaccine. I got deltoid muscle bursitis in my left shoulder and it lasted for weeks. Nasty stuff.
For the non-weaponized Y. pestis, your best bet is antibiotics (doxycycline usually).
Note here (CDC article) that a small percentage - 7% - of those vaccinated don’t produce antibody (same non-response is true of many other vaccines, there are always non-responders), some who don’t produce a protective level of antibody.
https://www.cdc.gov/mmwr/preview/mmwrhtml/00041848.htm