wooWe no longer worry too much about the severity of COVID, there are questions about whether the pandemic has left us exposed to other serious diseases. Massachusetts officials on Wednesday reported a rare case of a virus related to smallpox, called monkeypox. Smaller numbers of cases have also been reported in the UK, Canada, Spain and Portugal. Sam Fazeli, senior drug analyst at Bloomberg Intelligence, talks to Therese Raphael about what we know so far.
Therese Raphael: How is monkeypox related to smallpox and how is it spread?
Sam Fazelli: Monkeypox virus comes from the same family as smallpox – orthopoxvirus. It is most common in its family to infect humans after smallpox has been eradicated. It was not really thought of as an isolated infection until it was detected in a patient with smallpox in the Democratic Republic of the Congo in 1972. The disease caused by the virus is similar to smallpox, with initial fever, headache. and fatigue, followed by a rash two to four weeks later. Monkeypox has an incubation period of one to two weeks, similar to smallpox. The average case fatality rate of monkeypox in unvaccinated individuals has been reported as high as 10%-13%.
On transmission, the first thing to note is that monkeypox is a zoonotic infection, that is, it passes from animals to humans, and it can infect a wide variety, but there is little detail on this. Human-to-human transmission of monkeypox is thought to be through contact with saliva or respiratory droplets or skin lesions, but it is unclear how efficient airborne transmission is. It is possible for infected individuals to shed the virus before skin lesions occur, suggesting that asymptomatic transmission could theoretically occur. While transmission is thought to be less efficient than smallpox, there have not actually been many epidemiological studies on it.
TR: There are two strains of the virus, one more severe than the other. What are we seeing so far?
SF: The Congo Basin monkeypox virus strain is more pathogenic than the West African strain, with higher morbidity as measured by lesion numbers and mortality, which is 10%–13 for the East compared to 1% for the West African strain. % is calculated. , So the good news is that, at least in the UK, the cases so far appear to be of West African tension.
TR: Does the fact that transmission is not airborne suggest that we are unlikely to see that kind of exponential increase in use cases with SARS-CoV-2? What kind of numbers will raise concerns about the outbreak?
SF: Transmission may occur via respiratory droplets, although not enough studies have been done to be sure how efficient this is. Remember that the problem with SARS-CoV-2 was that it was also transmitted by aerosols, which can linger in a room for much longer than droplets, which fall to the ground relatively quickly. But given its mortality rate, even the less virulent West African strain, and the fact that many young people born after their 70s do not have immunity to the virus, even That even low rates of transmission can have dramatic social effects.
TR: Do current vaccines protect against monkeypox? Are there antiviral treatments that work for those who do get sick?
SF: We have both. Two vaccines are approved for smallpox, although one is actually approved for monkeypox. The Bavarian Nordic’s Jynneos is approved by the US Food and Drug Administration and several other regulatory agencies for both smallpox and monkeypox, while Emergent BioSolutions Inc./Sanofi’s ACAM2000 is approved only for smallpox, although also against monkeypox. likely to work.
The biggest difference between the two vaccines is safety, with ACAM2000 carrying a black-boxed warning on its FDA label about the risk of myocarditis/pericarditis, which was observed at a high rate of 5.7 cases per 1,000 people. There are other side effects that may prevent its widespread use.
There are medicines too. Chimerix’s Tembexa capsule and liquid formulation, which the company is in the process of selling to Emergent BioSolutions, was approved by the FDA in June 2021 for the treatment of smallpox infections. It has shown activity against monkeypox in animal models, but I am not aware of data in humans. SIGA’s Tpoxx capsules were approved in 2018 and a liquid formulation has since been developed.
TR: The fact that we’re seeing it emerge now – is this pure coincidence or does it suggest that the pandemic has weakened immunity enough to allow something like this to seed?
SF: It has nothing to do with the weakened immunity associated with the pandemic. You could say that about the flu or the common cold virus or even the respiratory syncytial virus, but that’s not the case. What is probably going on is that global levels of immunity to orthopoxviruses have declined since the last smallpox vaccination campaign ended in the 1970s. As such, not only are many people born and not vaccinated against smallpox, but there may have been some decline in immunity to the infection, even among those who were vaccinated a long time ago. was imposed.
TR: So should we be worried about monkeypox?
SF: I would say it depends on when and where you were born, which determines your vaccination status. There is clear data in non-human primates showing that those vaccinated with the smallpox vaccine were protected against a lethal dose of monkeypox. For people who are too young to be vaccinated against smallpox, the risk is likely to be in the ranges outlined above.
The biggest question is whether the infection will spread or can they be controlled quickly. One way is to use ring vaccination, that is, to vaccinate individuals in areas where a case has been detected – and of course those who are at risk of coming into contact with infected individuals. As such, the transmission chain can be broken much more easily than SARS-CoV-2. Whether the virus has mutated in a way that has increased its transmission is unknown.
It is still very early days and we have the tools to help manage outbreaks. But we need to be very cautious given the morbidity/death risk of the virus.
Read also: Monkeypox cases confirmed in UK and US: Experts discuss whether it is cause for concern