Delinking a vaccine from intestine disorder

#GS3 #SCIENCE #HEALTH

A new study finds India's rotavirus vaccine, Rotavac, is not associated with common disorder.

  • In a number of countries, studies have associated vaccination against rotavirus with a small risk of an intestinal disorder, called intussusception. 
  • A new study has now found that the rotavirus vaccine Rotavac, produced in India, was not associated with intussusception in Indian infants.

 

Rotavirus and intussusception

  • Rotavirus is the most common cause of severe diarrhoeal disease in children worldwide. 
  • According to the World Health Organization (WHO) and UNICEF, diarrhoea-related diseases account for more than 1 in 10 under-five deaths. 
  • Rotavirus accounts for 37% of diarrhoea-related deaths, and 5% of all deaths in under-five children globally.
  • Rotavac is an oral, live attenuated vaccine that contains a naturally occurring strain of rotavirus. It is administered in a three-dose series at 6, 10, and 14 weeks of age.
  • Intussusception is a sliding of one part of the intestine into another, and is common in children (1 in 300 in Vietnam; 1 in 2,000 in the US) without a cause. 
  • In adults, there is usually a reason like a tumour or other intestinal condition. Intussusception is considered a common surgical emergency in children, sometimes involving obstruction of the intestine which can be fatal if not treated.
  • Studies from Australia, England, Mexico, Singapore, and the US States showed an increase in the risk of intussusception by a factor of 2.6 to 8.4. 
  • Studies from Australia and the US showed that RotaTeq vaccination was associated with an increase in the risk of intussusception by a factor of 2.6 to 9 in the 21 days after vaccination. 

 

Intussusception in India

  • There is not enough background data about how common this disorder is in India. There are studies that show it happens in 1 in about 5,000 children normally without the vaccine but these are based on a very small number of cases.
  • Two studies have shown a general incidence of 18 intussusception cases per 100,000 infants and 20 cases per 100,000 Indian infants.

     
  • In a 2014 phase 3 trial before Rotavac was licensed, the vaccine had an efficacy of 56% against severe rotavirus gastroenteritis. 
  • However, that trial with 6,799 infants (including those given a placebo) was not large enough to detect a small increased risk of intussusception. 
  • Hence, this new study was undertaken and an Indian Intussusception Surveillance Network was set up.
  • The Rotavac vaccine was not proven in terms of its association with intussusception when it went into the programme because the vaccine was only evaluated in 4,500 vaccinated children, which is not enough to give a signal for safety.

 

Findings, and importance

From April 2016 through June 2019, 970 infants with intussusception were enrolled, and 589 infants who were 28 to 365 days of age included in the case-series analysis. The relative incidence of intussusception after the first dose was 0.83 in the first 7 days, and 0.35 in the next 14 days. Similar results were observed after the second and third doses. “The results of our postmarketing active surveillance study, which studied children vaccinated after the vaccine was introduced into the National Immunisation Programme, provide evidence that there was no adverse safety signal associated with this vaccine in the Indian population.

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