The Centers for Disease Control and Prevention (CDC) in the US has recommended expanded use of Pfizer's pneumococcal conjugate vaccine Prevnar 13 in immunocompromised adults aged 19 or over, opening up a new market for the blockbuster product.
The Prevnar franchise is already a major growth line for Pfizer, bringing in $3.7bn last year from its use to prevent pneumococcal disease in children aged six weeks to five years of age, and also in adults aged over 50 based on their immune response to the vaccine.
The new indication backed by the CDC's Advisory Committee on Immunisation Practices (ACIP) extends use of the Prevnar 13 vaccine into adults with conditions such as functional or anatomic asplenia, HIV infection, cancer, advanced kidney disease, or other immunocompromising conditions.
The number of immunocompromised patients in the population is hard to gauge, but some estimates are as high as 10m people. The ACIP also suggested there may be a benefit in high-risk patients receiving Prevnar 13 in addition to Merck & Co's older polysaccharide vaccine Pneumovax 23.
Meanwhile, Pfizer is conducting a variety of clinical studies using Prevnar 13 in immunocompromised individuals and expects results at the end of 2012 and into 2013.
The company is also bidding to expand the use of Prevnar into older children aged between five and 17 years, as well as routine use in the people aged over 50, regardless of their immune status.
ACIP is waiting for the results of an ongoing 84,000-patient trial called CAPiTA (Community-Acquired Pneumonia Immunisation Trial in Adults), which will look specifically at the vaccine's efficacy in reducing pneumococcal pneumonia and invasive disease, before delivering a verdict on broader use in the over-50s. Pfizer has said it expects to publish the findings of that study next year.
"Pfizer believes that Prevnar 13 offers a significant health benefit and compelling value proposition for the US health care system," said the company in a statement.
"We are committed to continuing discussions with the ACIP with the aim of expanding the recommendations to include all adults 50 years of age and older – a population rapidly increasing in the US and at risk for developing vaccine-type pneumococcal pneumonia and invasive disease."
ACIP recommendations are considered critical to ensuring a good take-up rate for vaccines in the marketplace, and analysts have suggested that use in adults could drive sales of Prevnar up above $6bn a year.
The vaccine is known as Prevenar in certain countries outside the US.