Investigator says asymptomatic people can transmit Mpox

Researcher Ana Abecasis says the latest Mpox variant may be asymptomatic, but its transmission potential is not well understood, and that vaccination is the most effective way to combat it.

“There may be asymptomatic cases – which I think are fewer in this pathology – but the possibility of transmission from asymptomatic people is not yet fully understood,” explains Lusa, associate professor at the Institute of Hygiene and Tropical Medicine (IHMT) of the New University of Lisbon.

The latest outbreak of Mpox, previously called “monkeypox,” is caused by “clade I” from Central Africa, which is different from the one that caused the 2022 outbreak with several cases in Europe, “clade II” from East Africa, the study says.

“These ‘clades’ have different characteristics in terms of symptoms,” he says.

Clade II causes less frequent and more localized rashes, while Clade I has a rash that is more scattered throughout the body, causing more severe symptoms. However, symptoms such as fever, headaches, and lymphadenopathy [condição em que os nódulos linfáticos ficam com tamanho, consistência ou número anormais] “common in both cases,” he says.

The latest strain appears to be more virulent, although the researcher stressed that she has not yet found “clear information regarding mortality rates.”

“This strain is described as having a higher mortality rate, and the information I found is that the percentage is between 1 and 10%, while for ‘clade II’ it is between 2 and 6%, but it also depends on the affected areas,” he emphasizes.

Ana Abecasis explains that mortality rates between strains should not be directly compared because the 2022 outbreak was in Europe, which has greater response capacity, while the current outbreak is mostly affecting Africa, where there is a lack of infrastructure and health professionals.

Clade I is more likely to be transmitted from person to person, making it easier to spread, and the first case in Europe was announced in Sweden on Thursday, so “there is a high need for prevention,” he said.

In particular, with regard to Africa, “the best response (…) to combat this outbreak is prevention, because in terms of the ability of human health resources to respond to treatment, we know that we have limited resources in these contexts, and ultimately that makes it harder to play,” he laments.

Therefore, prioritizing vaccination “will be the best strategy to try to overcome the shortage of human resources,” he advises.

The World Health Organization (WHO) has a number of recommendations ranging from early diagnosis, case isolation, partner notification, contact tracing and vaccination, but the number of vaccines available is still small, he says.

The challenge now is to produce, distribute vaccines and prioritise high-risk people for vaccination, but local contexts can complicate these efforts.

However, the Gavi Vaccine Alliance, whose president is Durão Barroso, a former Portuguese prime minister, has a response plan with a financial budget of about €455 million dedicated to this type of emergency and announced on Friday the creation of a global reserve of IPC vaccines.

“In this case, we will have to ensure that these vaccines are distributed in a coordinated manner and that structures at the local level can monitor emerging cases and identify contacts in order to prevent the epidemic from spreading rapidly,” the head of government researcher says.

The professor believes it is extremely important to identify high-risk groups.

“I haven’t seen anything yet that would define high-risk groups in this case. We know that children have a lot of infections, that there is vertical transmission and in this case the mortality rate is higher,” he emphasizes.

Research and preparedness efforts have been underway for smallpox since the previous outbreak in 2022, he said.

As for Portugal, “there must be awareness among health workers of the symptoms of this disease or the spectrum of symptoms in terms of the possible existence of imported cases so that we can immediately take measures to isolate them,” it said.

“I also don’t know what is planned in terms of monitoring the entry of people from these hardest hit regions, but it is important to have some surveillance, which would be an effective strategy,” he advises.

However, he stressed that resource management and understanding of the extent to which mass testing can be carried out at borders are needed.

Portugal has already vaccinated about 17,000 people who were at high risk of an outbreak in 2022, he said.

The researcher also emphasizes that, in her opinion, “all available vaccines should be directed to countries that are currently experiencing outbreaks, but at some point it may make sense to also vaccinate the Portuguese population, and there should also be a definition of a vaccination strategy that identifies priority groups, namely health workers who are most likely to come into contact with patients,” he concluded.