Family Updates

In August of 1998, a live attenuated tetravalent Rotavirus vaccine was licensed by the Food and Drug Administration. The vaccine was developed at the National Institutes of Health (NIH) and is licensed to Wyeth-Lederle Vaccines and Pediatrics. The vaccine is known as Rotashield or RRV-TV. It contains a rhesus Rotavirus with serotype G3 specificity and reassortant rhesus -human Rotaviruses with G1, G2, G4 specificity. Therefore, a single vaccine provides immunity to the four most common Rotavirus serotypes.

How the RRV-TV vaccine is made. Reprinted from Emerging Infectious Diseases, Volume 4 Number 4, Oct-Dec 1998.

Four placebo controlled randomized clinical trails performed in industrialized countries have demonstrated the efficacy of the vaccine. It provides 50% protection against any diarrhea caused by Rotavirus and more importantly, it provides about 70%-95% coverage against severe diarrhea caused by Rotavirus.

The effects of the RRV-TV vaccine in unindustrialized countries are less certain. Several factors influence its role: younger age of infection, possible greater particle exposure, different strains of Rotavirus, poorer nutritional status and interference by other diarrhea causing pathogens. However, in a study in Venezuela, high rates of RRV-TV efficacy were observed, approaching levels seen in studies done in industrialized countries.

The vaccine is administered in three oral doses at 2,4, and 6 months of age. The first dose, however may be administered as early at 6 weeks of age with a minimum interval between doses of 3 weeks. It is unknown whether the vaccine will protect equally as well if less than three doses are given. The vaccine is currently priced at 10-30 dollars per-dose, a high price which may reduce its feasibility in unindustrialized countries.

The vaccine is stored at room temperature, making it accessible even in conditions where refrigeration is not possible. It is not known whether the spread of vaccine virus, which has been observed, can lead to herd immunity, protecting not only the child but also those who interact with the child. If herd immunity is a possibility, it may be possible to offer the vaccination in limited numbers in unindustrialized coutries, while still providing coverage to most.