Explainer: What vaccines, treatments do we have to combat monkeypox?
25/05/2022 11:57
By Natalie Grover
LONDON, May 25 (Reuters) - With cases of monkeypox
inexplicably on the rise outside of Africa - where the viral
disease is endemic - public health officials are using contact
tracing, isolation and targeted vaccination to curb its spread.
Global health officials have tracked more than 200 suspected
and confirmed cases of the usually mild viral infection in 19
countries since early May. The monkeypox variant implicated in
the current outbreak has a case fatality rate of around 1%,
though no deaths have been reported so far. urn:newsml:reuters.com:*:nL2N2XG1LI
Here's what we know about the existing range of vaccines and
treatments:
VACCINES
The smallpox and monkeypox viruses are closely related, and
the first generation of smallpox vaccines appear up to 85%
effective in preventing monkeypox, the World Health Organization
has said.
There are currently two smallpox vaccines available.
One made by Danish company Bavarian Nordic BAVA.CO goes by
the brand name Jynneos, Imvamune or Imvanex - depending on
geography.
It contains a weakened form of the vaccinia virus that is
closely related to, but less harmful than, than the viruses that
cause smallpox and monkeypox. This modified version of vaccinia
does not cause disease in humans and cannot reproduce in human
cells.
It has U.S. approval for the prevention of both smallpox and
monkeypox. European Union approval is for smallpox, although
doctors can prescribe it off-label for monkeypox. Bavarian
Nordic said it would probably apply for a label extension with
the EU's drug watchdog to include monkeypox.
The reported side-effects include pain and swelling at the
injection site as well as headache and fatigue.
The other, older vaccine, currently made by Emergent
Biosolutions EBS.N , is called ACAM2000.
It also contains the vaccinia virus, but it is infectious
and can replicate in humans. As a result, it can be transmitted
from the vaccine recipient to unvaccinated people who have close
contact with the inoculation site.
Apart from side-effects associated with many vaccines, such
as a sore arm and fatigue, it also carries a serious warning for
a potential range of severe complications, including heart
inflammation, blindness and death.
It is also not designed to be used in certain groups of
people, such as those with compromised immune systems.
ACAM2000 has U.S. approval for people at high risk for
smallpox infection. It does not have EU authorisation.
ANTIVIRALS
Symptoms of monkeypox - which can include fever, headaches,
distinctive rashes and pus-filled skin lesions - can last for
two to four weeks and often resolve on their own.
Patients may receive extra fluids and treatment for
secondary bacterial infections. An antiviral agent called
tecovirimat - branded as TPOXX and made by SIGA Technologies
SIGA.O - has U.S. and EU approval for smallpox, while its
European approval also includes monkeypox and cowpox.
Another drug, branded as Tembexa and developed by Chimerix
CMRX.O , has U.S. approval to treat smallpox. It is not clear
whether it could help people infected with monkeypox.
Both TPOXX and Tembexa were approved based on studies in
animals showing they are likely to be effective, because they
were developed after smallpox in human beings had been
eradicated through mass vaccination.
STOCKPILES
The WHO classified smallpox as an eradicated disease in
1980, but there have been longstanding concerns that the virus
could be used as a bioweapon, leading countries to stockpile
vaccines.
The WHO holds 2.4 million doses at its Swiss headquarters
dating from the final years of the eradication programme. The
agency also has pledges from donor countries for more than 31
million additional doses.
U.S. officials say there are more than 1,000 doses of the
Bavarian Nordic vaccine in the national stockpile and expect
that level to ramp up very quickly in the coming weeks. The
country also has 100 million doses of ACAM2000. urn:newsml:reuters.com:*:nL2N2XF1WQ
Germany has said it had ordered 40,000 doses of Bavarian
Nordic's vaccine, to be ready to vaccinate contacts of cases if
needed. urn:newsml:reuters.com:*:nL5N2XG3JI
Other countries, including Britain and France, are also
offering or recommending vaccines to people with close contact
to infected people and healthcare workers. urn:newsml:reuters.com:*:nL2N2XG1LI
Bavarian Nordic, which has an annual production capacity of
30 million doses, told Reuters multiple countries have
approached it interested in buying its vaccine, without
providing details. A spokesperson said it does not need to
expand production. urn:newsml:reuters.com:*:nL5N2XG5LK
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FACTBOX-Countries offering vaccine for monkeypox urn:newsml:reuters.com:*:nL5N2XG3YE
FACTBOX-Monkeypox cases around the world urn:newsml:reuters.com:*:nL5N2XF1XF
EXPLAINER-How concerned should we be about monkeypox?
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(Reporting by Natalie Grover in London; Twitter @NatalieGrover;
Additional reporting by Nikolaj Skydsgaard in Copenhagen and
Michael Erman in New Jersey; editing by Michele Gershberg,
Josephine Mason and Jane Merriman)
((natalie.grover@thomsonreuters.com;))