April 28, 2009

Pandemic vaccine can take six months

British researchers warn of a six-month time lag before effective vaccines can be manufactured in the event of a pandemic.

Unfortunately, if a pandemic occurs, it will take up to six months to manufacture effective vaccine, so the first waves of the pandemic may be over before people are vaccinated, Dr. Iain Stephenson of the Leicester Royal Infirmary and the University of Leicester said in a statement. Furthermore, most people need two doses of H5 pandemic vaccine to get protection -- so this adds a further delay.

The major current threat seems to be from avian influenza H5N1, Stephenson said.

Stephenson and his team conducted a study comparing the effect of a single H5 bird flu vaccine dose to people who had been vaccinated with an H5 vaccine previously with people who had not previously received vaccine. The aim was the test out the idea of a pre-pandemic vaccination approach.

We found that those people who received H5 vaccine between 1999 and 2001 responded very well to a single dose of a newer H5 vaccine. They had memory cells that gave a rapid protective response within seven days of the repeat vaccine, Stephenson said. The response was very broad and able to protect against all known strains of H5N1 virus.

The findings are published in the Proceedings of the National Academy of Sciences.