Rotavirus Infection Gives Lower Protection in all over India
Rotavirus infection in India tends to occur early in life, has higher reinfection rates, and lower rates of protection against severe gastroenteritis than reported elsewhere, according to a study published in the July 28 issue of the New England Journal of Medicine.
Beryl P. Gladstone, Ph.D., from the Christian Medical College in Vellore, India, and colleagues examined the protective effect of rotavirus infection on subsequent infection and disease in 373 children recruited at birth from urban slums in Vellore, India, and followed-up for three years with twice-weekly home visits. Enzyme-linked immunosorbent and polymerase-chain-reaction assays were used to analyze stool samples collected every two weeks and on alternate days during diarrheal episodes. Seroconversion, an increase in IgG or IgA antibody levels by a factor of four or three, respectively, was evaluated in serum samples taken every six months.
The investigators found that rotavirus infection usually happened early in life, with 56 percent of children infected by the age of 6 months. Reinfection levels were found to be high, with only about 30 percent of infections being primary. Although an increase in protection against moderate or severe disease was associated with the order of infection, the protection was only 79 percent after three infections. There was no evidence of homotypic protection for most common viral strain, G1P.
"Early infection and frequent reinfection in a locale with high viral diversity resulted in lower protection than has been reported elsewhere, providing a possible explanation why rotavirus vaccines have had lower-than-expected efficacy in Asia and Africa," the authors write.