H1N1 vaccines
How safe are H1N1 vaccines?
A wide range of measures are in place to monitor and review the safety of H1N1 pandemic vaccines, including (pre-)clinical testing, regulatory assessment, and wide-scale monitoring. This builds on the extensive safety record established with seasonal influenza vaccines over the last 60 years in a wide range of age and risk groups. Pandemic H1N1 vaccines have also been subjected to all these rigorous precautionary measures before release. Hundreds of millions of vaccine doses have now been distributed but the total number of vaccines that have been used is not clear at this moment. No unexpected safety problems have surfaced until today. This in spite of active post marketing surveillance activities implemented by regulators and manufacturers in many countries.
Are the adjuvants contained in a number of new H1N1 vaccines safe?
Besides several regulatory authorities also WHO experts have supported the production and use of adjuvanted pandemic H1N1 vaccines, particularly in light of their potential to stretch vaccine supplies and protect against different, though related virus strains. In addition, there is significant preclinical and clinical evidence supporting the use of adjuvants in influenza vaccines to decrease the antigen content and increase the duration and breath of the protection they induce with novel virus strains. The adjuvants used in pandemic H1N1 vaccines had undergone extensive animal testing and clinical trials in tens of thousands of subjects before they were used, whereas one of the adjuvants had already been used in millions of influenza vaccine doses for the elderly. The experience gained with vaccines containing these adjuvants, both in clinical studies and wider immunization campaigns, shows that although they may cause more local side effects, their overall safety profile is largely similar to those of non-adjuvanted vaccines. Before any H1N1 vaccines were used in pandemic immunization campaigns they had all received regulatory approval.
Can pandemic vaccines be approved for use very quickly without new clinical data?
Regulatory authorities have developed processes to accelerate the approval of vaccines and to allow rapid use without compromising safety. These procedures build on the extensive experience gained with seasonal influenza vaccines. This experience shows that changing the viral strain in vaccines produced using the same manufacturing, quality and control processes does not substantially affect the safety or protection offered. This has allowed regulators to review safety and efficacy of both seasonal and pandemic influenza vaccines against newly emerging viruses, by taking into account previously approved procedures used for seasonal or prototype pandemic vaccines.
