The #GoogleDoodle today recognizes virologist Michiaki Takahashi, who developed the Oka strain of VZV (varicella-zoster virus), the causative agent of chickenpox and herpes zoster (shingles).
Let's take a minute to talk about why it matters.
Let's take a minute to talk about why it matters.
Chickenpox has a low mortality in healthy children & it was highly prevalent, but in children with immune deficiencies, it was a significant cause of death.
As many as 10% of children with leukemias would survive their cancer into remission, only to die suddenly of acute VZV.
As many as 10% of children with leukemias would survive their cancer into remission, only to die suddenly of acute VZV.
So the goal for a chickenpox vaccine, in addition to reducing disease burden and rare complications, was to increase the survivability of childhood cancers.
The Oka strain was taken from a 3 yr old boy in Japan who was otherwise healthy, then passaged (grown) many times...
The Oka strain was taken from a 3 yr old boy in Japan who was otherwise healthy, then passaged (grown) many times...
As the virus was being passaged, it was mutating without any constraints from an immune system. After 28 passages in various human and guinea pig cell lines, the resulting strain had accumulated mutations that made it less pathogenic.
It had become 'attenuated' by culturing.
It had become 'attenuated' by culturing.
The obvious concern if you're going to give children infectious VZV is that it doesn't create it's own epidemic, or revert back to a pathogenic disease.
Fortunately, the trials were taking place in the first years of PCR, and it was easy to tell vaccine from wild type strains.
Fortunately, the trials were taking place in the first years of PCR, and it was easy to tell vaccine from wild type strains.
The resulting attenuated strain was safe in healthy kids, and even relatively safe in immunocompromised kids, with serious rashes and transmission still a concern.
The form used in the US is 82% effective at preventing infection, 100% effective at preventing serious disease.
The form used in the US is 82% effective at preventing infection, 100% effective at preventing serious disease.
Two doses greatly increase efficacy.
A personal note: I was too young to have received the vaccine, and developed chickenpox at age 17, which prevented me from leading my forensic debate team to the State finals. ☹️
A personal note: I was too young to have received the vaccine, and developed chickenpox at age 17, which prevented me from leading my forensic debate team to the State finals. ☹️
I'll skip over a discussion of how a "shingles vaccine" can save you from the worst pain you're likely to experience short of being set on fire, but we have Dr. Michiaki Takahashi to thank for that too.
Thank you, to all the virologists out there, for the good work you do!
Thank you, to all the virologists out there, for the good work you do!
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