lessons learnt from smallpox eradication and post-eradication strategy

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Dr. David Ulaeto © Crown copyright 2014 Dstl 21/06/22 Lessons learnt from smallpox eradication and post-eradication strategy

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Page 1: Lessons learnt from smallpox eradication and post-eradication strategy

Dr. David Ulaeto

© Crown copyright 2014 Dstl

3 May 2023

Lessons learnt from smallpox eradication

and post-eradication strategy

Page 2: Lessons learnt from smallpox eradication and post-eradication strategy

Outline

• Variola virus and orthopoxviruses• Smallpox and its eradication• Sequestration of variola virus after eradication• Regulation of variola virus repositories & research• Emergence of related viruses

3 May 2023

©Dstl 2016

Page 3: Lessons learnt from smallpox eradication and post-eradication strategy

Genus Orthopoxvirus

• Members: variola (smallpox), monkeypox, cowpox, vaccinia, ectromelia, raccoonpox, taterapox, camelpox, rabbitpox, buffalopox

• All are morphologically identical• All are immunologically related and confer protection

against other members of the genus

3 May 2023

©Dstl 2016

Page 4: Lessons learnt from smallpox eradication and post-eradication strategy

Why Was Smallpox Eradication Possible?• No animal reservoir• No latent or persistent infection• Smallpox was an easily recognised disease• The vaccine was effective against all strains of

virus• Vaccine properties. Efficacy, potency, low cost,

abundance, heat stability, easy administration• WHO determination

3 May 2023

©Dstl 2016

Page 5: Lessons learnt from smallpox eradication and post-eradication strategy

Smallpox Control

3 May 2023

Lady Mary Wortley MontaguVariolation 1721

Edward JennerVaccination 1796

©Dstl 2016

Page 6: Lessons learnt from smallpox eradication and post-eradication strategy

Smallpox Eradication • 1721. Variolation• 1796. Vaccination• 1801. Eradication predicted• 19th century. Vaccination spreads throughout the world

• 1950. Freeze dried vaccine developed

3 May 2023

©Dstl 2016

Page 7: Lessons learnt from smallpox eradication and post-eradication strategy

Smallpox Eradication • 1959. WHO adopts Russian proposal to eradicate smallpox• 1967. Intensified eradication campaign begins• 1975. Last case in India• 1977. Last case in Somalia – last endemic case in the

world• 1978. Last case in the world – Birmingham, UK • 1980. Eradication certified by WHO• 1993. Genome of variola virus sequenced• ???? Last stocks of variola virus to be destroyed

3 May 2023

©Dstl 2016

Page 8: Lessons learnt from smallpox eradication and post-eradication strategy

Sequestration of Variola VirusAfter Smallpox Eradication• WHO writes to all governments• WHO writes to all Virus laboratories• WHO scans index medicus for variola research

– Writes to directors

• WHO requests destruction or transfer of all stocks

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©Dstl 2016

Page 9: Lessons learnt from smallpox eradication and post-eradication strategy

Sequestration of Variola VirusAfter Smallpox Eradication• In 1975, 75 laboratories held variola virus

stocks

3 May 2023

Year No of Laboratories

1975 75

1977 18

1978 13

1979 7

1980 6

1981 4

1982 3

1983 2

©Dstl 2016

Page 10: Lessons learnt from smallpox eradication and post-eradication strategy

Sequestration of Variola VirusAfter Smallpox Eradication• Forgotten stocks have been discovered on at

least 4 occasions

3 May 2023

Year No of Laboratories

1979 USA

1979 Tanzania

1985 UK

2014 USA

©Dstl 2016

Page 11: Lessons learnt from smallpox eradication and post-eradication strategy

Sequestration of Variola VirusAfter Smallpox Eradication• Centralised in 2 locations:

– CDC, Atlanta, USA– Vector, Novosobirsk, Russia

• Maximum security lab’s• Biennial inspection by WHO• All work with live variola virus requires prior

approval by WHO

3 May 2023

©Dstl 2016

Page 12: Lessons learnt from smallpox eradication and post-eradication strategy

Why Retain Variola Virus AfterSmallpox Eradication?• Smallpox is a human disease *• Treatment requires anti-virals *

– Brincidofovir– Tecovirimat

• The vaccine has significant side-effects *– A safer vaccine is required

• Modern diagnostics

• * These rationales do not apply to rinderpest

3 May 2023

©Dstl 2016

Page 13: Lessons learnt from smallpox eradication and post-eradication strategy

Emergence of Related Viruses

• Monkeypox– Human infection only apparent since 1970

• Clinically similar to smallpox• Virus closely related to variola• Controlled by smallpox vaccine

3 May 2023

©Dstl 2016

Page 14: Lessons learnt from smallpox eradication and post-eradication strategy

Emergence of Related Viruses: The Human Niche

3 May 2023

Smallpox Vaccine Empty Monkeypox?

• Smallpox eradication opened an ecological niche

©Dstl 2016

Page 15: Lessons learnt from smallpox eradication and post-eradication strategy

Why is this important?

• Eradication – leads to loss of herd immunity– Vulnerability to deliberate or accidental release

3 May 2023

©Dstl 2016

Page 16: Lessons learnt from smallpox eradication and post-eradication strategy

Summary• Identification of laboratories and stocks is

essential• Oversight of handling laboratories is essential

– Accidental releases have occurred– Birmingham 1978 – after last endemic case

• Emergence of related viruses– e.g. monkeypox

• Bioterrorism/accident– The virus could be recreated– All research with virus must be regulated

• Diagnostics/surveillance– Subject to changing technology– Need to define requirements

3 May 2023

©Dstl 2016

Page 17: Lessons learnt from smallpox eradication and post-eradication strategy

Questions?

3 May 2023

©Dstl 2016

Page 18: Lessons learnt from smallpox eradication and post-eradication strategy

Questions?

3 May 2023

©Dstl 2016