There have been some very positive vaccine stories in the news recently for both vaccines that are on the market and those in development. First, a study conducted by Cincinnati Children’s Hospital found that the commercially available Human Papilloma Virus (HPV) vaccine, Gardasil, protected both vaccinated and unvaccinated women. The study published in the Journal, Pediatrics, demonstrated that HPV infection rates in women with the vaccine were cut by 69% and in women without the vaccine they were reduced by 49%. The reason for the drop in the unvaccinated population is a result of the beginning of “herd immunity”. Herd immunity occurs when a significant portion of a population is immune to the disease through vaccination. After this level of immunity is reached, there is a smaller chance that an unvaccinated person will come in contact with someone who is infected. Typically herd immunity is reached when 80% of the population has been vaccinated.
HPV is a serious public health concern and is responsible for the most common sexually transmitted infections. Even more worrisome is that HPV infections are responsible for 70% of cervical cancers, vaginal cancers and anal cancers. In addition an increasing number of head and neck cancers, especially in men, have been linked back to HPV. Overall approximately 20% of human cancers are caused by HPV infection. The Gardasil vaccine is specific against 4 of the roughly 100 strains of HPV. The study found that the infection rate of HPV strains not found in the vaccine was not reduced.
There are also several new vaccines in development that address significant threats to public health both in the United States and Worldwide. None is perhaps as significant as the recent developments with HIV vaccine research. One Reuters’ article “Scientists See AIDS Vaccine Within Reach After Decades,” explains how these developments have given scientists hope that an AIDS vaccine is possible and within our grasp in the next ten years. The article describes one exciting HIV vaccine candidate being developed by the U.S. Military HIV Research Program at the Walter Reed Army Institute of Research, Harvard University and Johnson & Johnson’s Crucell Unit. The vaccine uses weakened versions of a common cold virus and a smallpox virus. In a study published in February, it was shown that the vaccine protected monkeys from a virulent strain of HIV. “Safety studies in human patients are just starting, with large-scale efficacy studies slated for 2016.”
Additional noteworthy viral vaccines currently in clinical trials include:
*H5N1 (Bird Flu)
*Ebola & Marburg
Herpes Simplex Virus
Epstein Barr Virus (Mono)
Chikungunya Virus (transmitted via mosquitos)
These vaccines hold much promise in improving public health and can positively impact many lives. As a result we must strive to ensure the most safe and consistent manufacturing process possible. Ultimately this means removing animal products from manufacturing while still maintaining high viral yield.
Biopharmaceutical manufacturing, primarily using CHO cells, has made continual improvements over the years, including advances in media formulations to remove fetal bovine serum (FBS). However vaccine manufacturing in the United States has maintained many of the same practices including the use of animal products in media. One challenge is that manufacturing practices for many current vaccines were developed decades ago, before the rise of serum-free media technology. In addition, vaccines that have already received approval must apply for additional approvals by the Food and Drug Administration (FDA) whenever there is a manufacturing modification, a fact that has not served to motivate change in the industry.
However, new vaccine candidates that have not yet been through the approval process have the opportunity to improve vaccine manufacturing by removing animal products and increasing consistency. In fact, the FDA appears to be taking a stronger stance on animal products by recently publishing a guidance that would require a warning label be added to all products containing plasma-derived albumin in their manufacture. This would apply to many vaccines currently approved for use in the United States. The warning would state that due to the plasma-derived source of the albumin, the albumin may carry a risk of transmitting infectious agents, e.g., viruses, the variant Creutzfeldt-Jakob disease and the Creutzfeldt-Jakob disease agent. Please see our recent blog “FDA Issues Guidance for Warning Labels on All Drugs Produced Using Blood Products Including Plasma-Derived Albumin,” for more information.
One of the most effective ways to improve viral yield and remove animal products is to optimize cell culture media and manufacturing practices. We recently published a vaccine series, which covered “Strategies for Improving Viral Yield in Vaccine Manufacturing.” Included in the series was a discussion of strategies for improving vaccine manufacturing including: