A drug developed for smallpox was given to a person with monkeypox in 2021, and it seemed to shorten their illness compared with other cases
Health 24 May 2022
By Clare Wilson
Smallpox treatment may be useful for monkeypox cases
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An antiviral treatment developed for smallpox was successful in treating monkeypox – although, so far, results have been reported for only one person, so it is too soon to know how well it works.
A study of seven people who caught monkeypox since 2018 also found that people may be infectious for longer than we thought, as some tested positive for the virus on throat swabs for days after their skin lesions had healed, the point at which it was thought people are no longer infectious.
But we don’t know if that means they were still shedding live virus and so would have been infectious, says study co-author Hugh Adler at the Liverpool School of Tropical Medicine in the UK.
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“By that stage in the illness, it may well be that we’re just picking up pieces of dead virus,” says Jake Dunning at the University of Oxford, another study co-author.
Since 2018, two antiviral medicines have been given to people with monkeypox in the UK. These drugs were developed in case of a return of smallpox, which was eradicated in 1980 – smallpox and monkeypox are members of the same virus family.
Between 2018 and 2021, seven people with monkeypox were managed by doctors in a UK group that monitors serious infections, now under the UK Health Security Agency. This included frequently testing each person’s virus levels. Four caught the disease in Nigeria, one UK healthcare worker caught it from a patient in 2018 and two other people caught it from a member of their household.
All seven made a full recovery, whether or not they received antiviral medication, and no one became severely ill, although four were in hospital for four to five weeks and some developed painful ulcers.
The first three people received an antiviral called brincidofovir, but this didn’t seem to help and the treatment was stopped as they showed signs of liver inflammation, which may have been a side effect. Another three people received no antiviral medication.
The seventh person was given an antiviral called tecovirimat, taken as twice-daily capsules. Levels of virus in their blood and on throat swabs became undetectable within two days and they needed to stay in hospital for only 10 days. “It is only one patient, but it’s a signal that tecovirimat is a promising drug and should be taken forward for studies,” says Adler.
Paul Hunter at the University of East Anglia, UK, says only a randomised trial can reveal if the antiviral really helps. “We know from covid, observational studies can be misleading especially when, as in this case, the infection is usually self-limiting,” he says. “But at this stage of an epidemic, any little bit of information might be useful.”
Tecovirimat’s manufacturer, US pharmaceutical firm Siga Technologies, is studying the use of the drug in people with monkeypox in an observational study in the Central African Republic, where the disease is common in rodents.
Journal reference: The Lancet Infectious Diseases, DOI: 10.1016/S1473-3099(22)00228-6
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