LONDON –
With cases of monkeypox inexplicably on the rise outside Africa, where viral disease is endemic, public health officials are using contact tracing, isolation and targeted vaccination to curb its spread.
World health authorities have been monitoring more than 200 suspected and confirmed cases of generally mild viral infection in 19 countries since early May. The smallpox variant involved in the current outbreak has a mortality rate of around 1%, although no deaths have been reported so far.
Here’s what we know about the existing range of vaccines and treatments:
VACCINES
Smallpox and smallpox viruses are closely related, and the first generation of smallpox vaccines appears to be up to 85% effective in preventing smallpox, according to the World Health Organization.
There are currently two smallpox vaccines available.
A fact by the Danish company Bavarian Nordic bears the brand Jynneos, Imvamune or Imvanex, depending on the geography.
It contains a weakened form of the vaccine virus that is closely related to, but less harmful than, the viruses that cause smallpox and monkeypox. This modified version of the vaccine does not cause disease in humans and cannot be reproduced in human cells.
It has US approval for the prevention of both smallpox and monkeypox. European Union approval is for smallpox, although doctors may prescribe it off the label for smallpox. Bavarian Nordic said it would probably request an extension of the label with the EU drug control dog to include monkeypox.
Reported side effects include pain and swelling at the injection site, as well as headache and fatigue.
The other oldest vaccine, currently made by Emergent Biosolutions, is called ACAM2000.
It also contains the vaccinia virus, but is infectious and can be replicated in humans. As a result, it can be transmitted from the vaccine recipient to unvaccinated individuals who have close contact with the inoculation site.
Aside from the side effects associated with many vaccines, such as a sore arm and fatigue, it also carries a serious warning for a number of potential serious complications, such as heart inflammation, blindness, and death.
Nor is it designed to be used in certain groups of people, such as those with compromised immune systems.
ACAM2000 has US approval for people at high risk for smallpox infection. It does not have EU authorization.
ANTIVIRALS
Symptoms of monkeypox, which can include fever, headaches, distinctive rashes, and pus-filled skin lesions, can last two to four weeks and often resolve on their own.
Patients may receive additional fluids and treatment for secondary bacterial infections. An antiviral agent called tecovirimat, branded TPOXX and manufactured by SIGA Technologies, has US and EU approval for smallpox, while its European approval also includes monkeypox and bovine smallpox.
Another drug, branded Tembexa and developed by Chimerix, has US approval to treat smallpox. It is unclear whether it could help people infected with monkeypox.
Both TPOXX and Tembexa were approved based on animal studies showing that they are likely to be effective, because they were developed after smallpox in humans had been eradicated by mass vaccination.
STOCKS
The WHO classified smallpox as a disease eradicated in 1980, but there have long been concerns that the virus could be used as a biological weapon, leading countries to stockpile vaccines.
The WHO has 2.4 million doses at its Swiss headquarters dating back to the last years of the eradication program. The agency also has promises 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 reserve and expect that level to rise very rapidly in the coming weeks. The country also has 100 million doses of ACAM2000.
Germany has said it has ordered 40,000 doses of the Bavarian Nordic vaccine, to be ready to vaccinate case contacts if necessary.
Other countries, such as the United Kingdom and France, also offer or recommend vaccines to people with close contact with infected people and health workers.
Bavarian Nordic, which has an annual production capacity of 30 million doses, told Reuters that several countries have approached it with interest in buying its vaccine, without providing details. A spokesman said there was no need to expand production.
(Report by Natalie Grover in London; Twitter @NatalieGrover; additional report by Nikolaj Skydsgaard in Copenhagen and Michael Erman in New Jersey; edited by Michele Gershberg, Josephine Mason and Jane Merriman)