THE MAKING OF A VACCINE: Deeksha Tare recounts the twists and turns in a high profile and expensive chase for the rotavirus vaccine. Read her introduction to The Deadly Virus on Wheels here: http://goo.gl/suINZ and add her to your Science circle for more Viral Posts!
Originally shared by Deeksha Tare
Vaccine for the Wheels!!
Here goes the chain of events which led to the development of the Rotavirus vaccine:
1. Early Vaccine Studies
Rotavirus was considered to be a fastidious agent until the Wa Human Rotavirus strain was discovered in the stool of an infant with diarrhoea. It was grown successfully on African green monkey kidney (AGMK) cells after 11 passages in gnotobiotic piglets.
Thought to be a potential vaccine, clinical trials were commenced but then subsequently had to be called off due to contamination issues.
Similar was the fate of another human strain derived from an asymptomatic neonate. This strain (M37) failed to show protection in clinical conditions.
2. The Jennerian approach – RotaShield
This paved way for the Jennerian approach to the vaccine development. (Remember how Jenner prevented smallpox using cowpox virus?)
There are three great things about Rota-
a. Many different strains infecting different species
b. The segmented dsRNA genome
c. Once infected, it provides life- long immunity
Thus a recombinant vaccine could be made by co infecting cell culture with two different strains, which would lead to formation of attenuated strain.
So, the scientists made a Human- Rhesus reassortant, which passed clinical trials. (RotaShield)
3. The vaccine got licensed and was brought into use
4. The Intussusception issue
Fate was not in the favour of RotaShield 😦
CDC confirmed reports of the vaccine associated Intussusception
And the vaccine was withdrawn immediately.
5. The vaccine of current choice – RotaTeq
Paul A. Offit and H. Fred Clark developed a Human Bovine recombinant vaccine (RotaTeq).
Due to the intussusception reactions caused by the previous vaccine which led to its refusal subsequently, FDA wanted companies to prove that the vaccine did not cause the rare adverse reaction (intussusception) pre-licensure. As an effect a never-seen-before trial was carried out. A study that involved more than 70,000 children from 11 countries and cost about $350 million – (the largest vaccine safety trial ever performed by a pharmaceutical company!) by Dr. Edward Scolnick, president of Merck Research Laboratories at the time.
And thus finally in February 2006, the vaccine was recommended for routine immunization in children.
This is a great success story, which also “Raised the bar for vaccine efficacy studies” as said by Offit and Clark in the book
History of Vaccine Development
Thus mankind got a much needed vaccine finally to protect it’s young from the deadly rotaviral disease.