Monkeypox is a double stranded DNA virus, which means that due to the double stranded nature of DNA each of the two strands act as a “check” on the other during replication. As a consequence of this “error checking”, this and other DNA viruses mutate much more slowly than RNA viruses do. Over time, DNA virus genomes are relatively stable. This means that, unlike SARS-CoV-2 (COVID) or influenza, Monkeypox is unlikely to rapidly evolve to escape either naturally acquired or vaccine induced immunity. For the purposes of making a vaccine, this makes it a much easier target that say, a rapidly evolving RNA Coronavirus such as SARS-CoV-2, the virus which causes COVID-19. Furthermore, from an immunological point of view, the various Orthopox viruses often are cross-protective. In other words, if you have been vaccinated with a smallpox vaccine, or previously infected by Cowpox, Camelpox, or Monkeypox, you are highly likely to be quite resistant to disease caused by the Monkeypox virus which is now being (quite rarely) reported in non-African countries.
Current data indicate that Monkeypox is not very infectious in humans - it has a low Ro (perhaps below 1), which is the term used to describe how efficiency an infectious disease can spread from human to human. Again, this is super good news for containment. An Ro of <1 generally means that (even in the absence of social distancing of other containment measures), for every person already infected, on average less than one other person will become infected. For comparison purposes, the Omicron variants of SARS-CoV-2 have an Ro in the range of 7 to 10. A virus with an Ro of less than one can be easily contained with the standard public health methods discussed above. A virus with an Ro of 7-10 essentially cannot be contained and will rapidly spread throughout the world, as we have seen with the Omicron variants. In the case of a virus with an Ro around 1 or less, traditional infectious disease containment methods such as contact tracing, identification and isolation of infected individuals can be all that is needed to control the virus. Now the fact that Monkeypox is being spread from human to human (rather than only arising from contact between a person and an infected animal) is not such good news, but since this transmission appears to be from very close contact, this means that it can be easily contained without resorting to a general population vaccination campaign. In this type of setting, if there is a significant outbreak, vaccination is often restricted to just the health care and/or first responder personnel most likely to be in contact with an infected person. Using a vaccine to help that containment via either “ring” vaccination or wide-spread vaccination strategies is generally unnecessary, and may even be counterproductive, depending on the safety of the vaccine - keeping in mind that no drug or vaccine is perfectly safe.
Then it happened again! NDTV India ran a story yesterday headlined, “Belgium Detects 3 Monkeypox Cases, All Linked To Festival In Port City.” A festival? That sounds like fun. I reviewed the article to find out what kind of celebratory festival the Belgians were having that might have spread the monkeypox. It never occurred to me my “sexual network” information embargo was about to be shattered into a million tiny jagged pieces.
