An Ebola vaccine stockpile that mostly cannot wait for an outbreak

Ebola kills roughly half the people it infects. In 2021 the International
Coordinating Group (ICG) on Vaccine Provision established a **global stockpile
of ERVEBO** — the single-dose rVSVΔG-ZEBOV-GP vaccine — to make doses
available quickly and equitably when an outbreak starts.

Then the outbreaks did not come at the scale the stockpile was sized for, and
the stockpile ran into the problem every stockpile of a perishable good has.

The numbers

Shipments grew from **4,800 doses in 2021 to 13,870 in 2022 to 127,020 in
2023**. DRC received 111,000 (76%), Uganda 23,460 (16%), Guinea-Bissau
11,170 (8%).

Why so little went to outbreaks

Outbreaks since 2021 have been limited and rapidly contained. The 5% figure
is not a failure of distribution — it is what success looks like. **North Kivu,
DRC has received and administered more doses than any other area since 2018**,
which may itself have contributed to the rapid containment of later outbreaks
there.

**Four of the five outbreaks since 2021 were linked to reintroduction through
viral persistence**, rather than to fresh zoonotic spillover from animals —
the virus persisting in survivors and re-emerging, which is a different problem
from the one ring vaccination was designed to solve.

The expiry arithmetic

ERVEBO has a shelf life of three years. A stockpile held at 500,000 doses
against outbreaks that consume a few thousand will lose most of its contents to
the calendar. **More than 200,000 short-shelf-life doses due to expire in 2024
could be redirected for preventive vaccination** instead — which is the
report's central recommendation: **early planning for preventive vaccination
with short-shelf-life doses could be incorporated into stockpile management
strategies**, rather than treated as a leftover.

What preventive vaccination buys

Campaigns have targeted **health care workers and frontline workers in at-risk
countries**, who are exposed most. **Adding preventive vaccination of these
workers could reduce total cases, hospitalisations and deaths by an estimated
14–38%** compared with non-pharmaceutical measures and ring vaccination alone.

The evidence that the vaccine works came from DRC treatment facilities: **56%
of unvaccinated patients died, compared with 25% of patients vaccinated before
symptom onset.**

The two vaccines, and why only one is stockpiled

Fifty-six days is why the two-dose regimen cannot be the outbreak tool: the
outbreak is over, one way or another, before the second dose is due.

Source: Centers for Disease Control and Prevention, MMWR.