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BASED ON LENTZOS

ET AL.

the earlier Australian and Spanish efforts

and remains so for ongoing EU-funded ef-

forts to address African swine fever ( 7 , 15 ).

But one self-spreading vaccine development

program—to prevent Lassa virus transmis-

sion to humans in West Africa—is focused

on Mastomys rats, which are only distrib-

uted in sub-Saharan Africa ( 10 ), and moti-

vations for other studies also imply target

areas outside North America, where most of

this research is currently taking place.

Potential for repurposing these technolo-

gies is also a concern, where adversaries could,

for instance, deliberately use self-spreading

viruses, or vaccines, to cause harm. This,

too, needs to be addressed by those pushing

self-spreading vaccine development.

The technologies available to the

Australian and Spanish researchers’ dec-

ades ago were sufficient to develop mul-

tiple candidates, one of which progressed

to field trials and a licensing application

( 4 ). Molecular biology tools have advanced

since then, and arguably, little to no tech-

nological development is necessary to pro-

duce self-spreading viral vaccines today.

Without open and inclusive engagement

about potential benefits, risks, and appro-

priate precautionary measures from the

scientific and international communities,

self-spreading viruses for environmental

release could arguably be developed very

quickly, with limited funding or expertise

and with potentially irreversible conse-

quences for the planet’s biodiversity, eco-

systems, and environments. With only

modest technological innovation required,

typical risk mitigation measures, such as

increased education of scientists or the

creation of new international forums to

address governance, are likely to prove too

slow to have a constructive impact. It is no-

table that the time between the very first

peer-reviewed description of the Spanish

self-spreading rabbit vaccine and the sub-

mission for publication of the results of a

successful field trial ( 4 ) was just 12 months.

URGENT NEXT STEPS

Although earlier work on self-spreading vac-

cines coincided with, or was preceded by, reg-

ulatory engagement in multiple international

forums, like the OIE, WHO, the International

Plant Protection Convention (IPPC), and the

Convention on Biodiversity (CBD), current

developments appear to be taking place with-

out similar international efforts. The previous

regulatory discussions ultimately concluded

without resolving key safety and regulatory

questions ( 3 , 6 ), but there was a clear consen-

sus that, given the near inevitability of trans-

boundary movement, the appropriate forums

to consult were international ones.

A clear priority for the international com-

munity must be to update existing phyto-

sanitary, medical, and veterinary regu-

lations to reflect contemporary societal

values for responsible stewardship of sci-

ence—and specifically with respect to

environmental releases of self-spreading

viruses. Key principles that should be en-

dorsed and actively promoted include

safety, intergenerational justice, account-

ability, and public engagement. Immediate

opportunities are the CBD Conference of

the Parties (COP) and the meeting of its

Subsidiary Body on Scientific, Technical,

and Technological Advice (SBSTTA) in

spring 2022. Each provides a chance to

build on earlier CBD work ( 3 ).

Additional steps would be to establish

and implement a robust horizon-scanning

process and to develop a global consensus

on the criteria for safe, secure, and respon-

sible research and the evidence needed to

meet those criteria.

Echoing international efforts, national

governments should clarify and, if neces-

sary, update any relevant legislation and

guidance. In parallel, current developers

and funders of this research should articu-

late comprehensive and credible regula-

tory paths through which they believe the

safety and efficacy of self-spreading ap-

proaches could be established and through

which publics may accept the inherently

coercive and mandatory nature of self-

spreading vaccines.

Only a concerted, global governance ef-

fort with coherent regional, national, and

local implementation can tackle the chal-

lenges of self-spreading viruses that have

the potential to radically transform both

wildlife and human communities. This is

because, as the case for the rabbit hemor-

rhagic disease virus in Australia showed,

for self-spreading techniques, there is a real

possibility that the first regulatory approval

for a limited field trial could turn into an

unapproved international release ( 5 ). j

REFERENCES AND NOTES

1. M. W. Smithson, A. J. Basinki, S. L. Nuismer, J. J. Bull,
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3. Conference of the Parties to the Convention on
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4. J. M. Torres et al., Va c c i n e 19 , 4536 (2001).


5. P. O’Hara, Rev. Sci. Tech. 25 , 119 (2006).


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8. M. Cogley, “Could self-spreading vaccines stop a
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9. K. M. Bakker et al., Nat. Ecol. Evol. 3 , 1697 (2019).


10. PREEMPT, Prediction of Spillover and Interventional
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11. J. J. Bull, M. W. Smithson, S. L. Nuismer, Trends Microbiol.
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14. P. Van Damme et al., Lancet 394 , 148 (2019).


15. C. Gallardo et al., Transbound. Emerg. Dis. 66 , 1399
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ACKNOWLEDGMENTS

This article stems from a panel discussion at the 2020

EuroScience Open Forum, which was partially facilitated by

funding from the Max Planck Society. We thank participants

for discussions as part of that panel, as well as participants

in the 2019 “Going viral?” meeting that ran in parallel to the

Biological Weapons Convention Meeting of Experts (Geneva).

10.1126/science.abj5593

T1

T2

T3

T4

T5

Vaccine spreads throughout

the population over time.

T1 T2 T3

Self-spreading vaccines

T1

T2

T3

T4

T5

Only vaccinated individuals are

aected and maintained.

T1 T2 T3

Conventional vaccines

7 JANUARY 2022 • VOL 375 ISSUE 6576 33

Deployment strategies for self-spreading vaccines

At time T1, four members of a hypothetical population are directly vaccinated by injection (d). Only with a

self-spreading vaccine will immunity potentially expand to those not directly vaccinated (dd). Transmission

of the self-spreading vaccine occurs spatially (top) and temporally (bottom, to subsequent generations not

shown). The self-spreading vaccine provides some outwardly attractive opportunities if there is a need for rapid

vaccination of whole populations or difficulties in accessing individuals (this relies on the rather unrealistic

assumption that all individuals in the population remain naïve to infection by the self-spreading vaccine).