Monkeypox cases in the West have plummeted due to the fast roll-out of vaccines targeting the most at-risk people, marking one of the biggest public health successes of 2022.
In early May, the virus, which the World Health Organization (WHO) recently renamed mpox, was identified outside its endemic countries in West and Central Africa.
Cases quickly increased worldwide, with more than 100 new infections being reported every day by mid-June. After peaking at 1075 reported cases on 12 August, the incidences seemingly decreased as quickly as they rose, with just 37 new incidences being reported globally on 17 December.
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Early in the outbreak, Western countries were quick to order doses of the vaccine Imvanex. Although it is a smallpox vaccine, .
The UK, for example, ordered about 20,000 doses of Imvanex at the end of May. Towards the end of July, the UK Health Security Agency procured more than 100,000 additional vaccine doses, which were largely administered in London, the centre of the UK鈥檚 outbreak.
As well as ordering more doses, Western countries pivoted their vaccination efforts to target the most at-risk people. Initially, the vaccines were offered to close contacts of people who had been diagnosed with mpox.
Growing evidence then suggested that gay, bisexual and other men who have sex with men (GBMSM) who participated in group sex or attended sex-on-premises venues were among the most at risk, prompting countries to offer these individuals a vaccine.
Despite this, at the University of East Anglia, UK, says not enough at-risk people could get vaccinated anywhere until the jab started to be administered intradermally, below the top layer of skin, rather than subcutaneously, under the skin.
On 19 August, , helping more people get vaccinated. A clinical trial suggests that administering the vaccine intradermally or subcutaneously induces a similar immune response.
When it comes to mpox deaths, many countries 鈥� including the UK, France and Germany 鈥� have reported no fatalities. In the UK at least, this may be due to the country having an adequate supply of the antiviral drug tecovirimat throughout the outbreak.
There was initially only evidence that tecovirimat reduces the risk of death from mpox in animal studies, not human trials. Nevertheless, these early signs of efficacy meant that the drug was used to treat severe mpox and prevent complications in at-risk people, says at the University of Oxford.
Vaccines and treatments aside, communicating mpox鈥檚 risk to particularly at-risk people may have also helped to stem the outbreak, says Dunning. 鈥淲e think those at risk of becoming infected and transmitting their infections to others may have made behavioural changes, particularly around having sex, and this may have been a big contributing factor.鈥�
This idea is supported by evidence that in England, including those caused by shigella bacteria and a strain of chlamydia, says Dunning.
Mpox鈥檚 primary method of transmission also makes it easier to control than some other viruses, such as SARS-CoV-2. This coronavirus spreads quickly via aerosols in the air and can infect multiple people at once, says Hunter. In contrast, mpox is primarily transmitted via saliva and skin-to-skin contact, slowing its transmission.
Unlike SARS-CoV-2, mpox also hasn鈥檛 been mutating particularly quickly, says Dunning. New variants that could bypass immunity are therefore less of a concern with mpox than with covid-19.
While the number of reported mpox cases has plummeted, at the London School of Hygiene and Tropical Medicine thinks the decline could have been steeper had there been more education about the risks of certain sexual behaviours, alongside an even earlier vaccine roll-out.
Despite these potential shortcomings, has reported that President Joe Biden is preparing to end the US鈥檚 public health emergency declaration for mpox, with the country reporting no cases from 15 to 17 December. While no European country is expected to imminently relax its mpox response, some nations, including the UK and France, have similarly reported no recent cases.
According to Dunning, mpox cases aren鈥檛 sufficiently low globally to rule out a resurgence. The WHO still considers the outbreak to be a public health emergency of international concern, the highest alarm it can sound.
It is therefore important that eligible people take up the offer of a vaccine and stay vigilant for mpox symptoms, such as a fever, muscle aches and a chickenpox-like rash, says Hunter.
