Smallpox vaccine rollout to contain the spread of monkeypox

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Smallpox vaccine rollout to contain the spread of monkeypox

During our tenuous recovery from the COVID-19 pandemic, a spate of monkeypox cases is causing concern worldwide.1 As the most widely distributed monkeypox outbreak to date2, researchers and clinicians are looking at the smallpox vaccine as a vital tool to contain monkeypox outbreaks. Here, I summarize some key information on using a smallpox vaccine to contain and overcome the 2022 global monkeypox outbreak, along with challenges faced.

A short history

The first human monkeypox cases were identified in 1970 in the Democratic Republic of the Congo.3 The typical symptoms were similar to those of smallpox, albeit usually less severe.4 Most cases were confined to central Africa until the 1980s, when increasing numbers of cases appeared outside of the normal endemic range. Since then, significant but contained outbreaks have been recorded in the USA,5 Nigeria,6 Singapore,7 and the UK.8 Most monkeypox infections outside of the native range are of the less severe West African clade.4

Despite its name, rodents, not monkeys, are the major reservoirs of the virus, while most infections are from the human-to-human route.4

In May 2022, several reports were made to the WHO by member nations that are not endemic for the virus.9,10 This sudden spread in many new locales has stoked fears of another protracted battle against a new viral threat.3

The smallpox vaccine

Smallpox vaccines have been used to prevent the spread of monkeypox since the 1980s, and the Jynneos vaccine has a reported efficacy of up to 85% in preventing the spread of the virus.11 The vaccine also offers protection as post-exposure prophylaxis, meaning that vaccinating healthcare workers and close contacts of those infected can prevent further spread.11

To date, Jynneos is the only FDA-approved vaccine for monkeypox.12 The United States at present has 36,000 doses of the vaccine in its stockpile. Furthermore, Bavarian Nordic, the vaccine’s manufacturer, holds around a million doses and is capable of fulfilling an order for millions more if requested.13

Social challenges

Authorities quickly noted an apparent link between men who have sex with men (MSM) and the spread of monkeypox.14 While identifying people and groups with high rates of transmission is a lynchpin strategy when containing an outbreak, reporting on this link in the media presents the risk of increasing stigmatization of MSM.15 Furthermore, perceiving it as a “gay disease” can discourage patients from seeking treatment, potentially increasing the risk of infection.16 This can already be seen in Russian state television, where countries and people with monkeypox were mocked.17

More critically, the wave of anti-vaccine sentiment seen in the wake of COVID-19 has found a new target, both in falsely identifying COVID vaccines as a cause of monkeypox,18 and in recycled misinformation about a nefarious motivation for administering the smallpox vaccine.19

What’s to come

One clinical trial is hoping to identify the safety and efficacy of the anti-monkeypox drug TPOXX when used in combination with Jynneos.20 In the coming months, we can expect more studies to appraise the efficacy of Jynneos in containing the 2022 monkeypox outbreak, particularly given that there is still a lack of reliable recommendations for handling this outbreak.21


1.            Monkeypox: Cases outside Africa rise to 780 in three weeks - BBC News.

2.            Monkeypox data. (, 2022).

3.            Staff, S. What Is Monkeypox, And Could It Become The Next Pandemic? ScienceAlert

4.            Sklenovská, N. & Van Ranst, M. Emergence of Monkeypox as the Most Important Orthopoxvirus Infection in Humans. Front. Public Health 6, 241 (2018).

5.            July 15, 2003. Medscape

6.            Monkeypox in Nigeria - Watch - Level 1, Practice Usual Precautions - Travel Health Notices | Travelers’ Health | CDC.

7.            News Scan for May 09, 2019. CIDRAP

8.            [Withdrawn] Monkeypox case confirmed in England. GOV.UK

9.            Multi-country monkeypox outbreak in non-endemic countries.

10.          Monkeypox - United Kingdom of Great Britain and Northern Ireland.

11.          Monkeypox and Smallpox Vaccine Guidance | Monkeypox | Poxvirus | CDC. (2022).

12.          JYNNEOS Smallpox (Monkeypox) Vaccine.

13.          Kimball, S. U.S. has more than 36,000 Jynneos monkeypox vaccine doses immediately available in national stockpile. CNBC (2022).

14.          Why the monkeypox outbreak is mostly affecting men who have sex with men.

15.          UNAIDS warns that stigmatizing language on Monkeypox jeopardises public health.

16.          Monkeypox is spreading among gay men worldwide.

17.          Brugen, I. van. Russian state TV mocks other countries suffering monkeypox outbreak. Newsweek (2022).

18.          Monkeypox conspiracy theories: Five false claims about the virus debunked as misinformation spreads online.

19.          Following the ‘Covid playbook’: How conspiracy theorists are using old tricks around Monkeypox. Coda Story (2022).

20.          TPOXX Smallpox Monkeypox Treatment.

21.          Webb, E. et al. Availability, scope, and quality of monkeypox clinical management guidelines globally: a systematic review. (2022) doi:10.1101/2022.06.09.22276219.


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Published on: Jun 24, 2022

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