Developing a pandemic vaccine
It is widely recognised that vaccination has an important role in controlling outbreaks and pandemics of infectious diseases. In the next steps, we will learn how vaccination has been used successfully in some such situations. First, however, we will consider some of the processes and challenges faced in developing a pandemic vaccine.
Infectious disease outbreaks and pandemics are intermittent and can be unpredictable, therefore vaccines for new emerging infections simply do not exist at the time the threat is realised. Influenza viruses are considered to have high pandemic potential and over the past 15 years the World Health Organisation (WHO) has led efforts to ensure that the capacity to manufacture pandemic influenza vaccines is increased. In addition, the WHO has identified other potential infections that could cause a global emergency for which vaccines are not available in order to stimulate research and development into these infections. This list includes infections like the Middle East Respiratory Syndrome (MERS), which is in the same family as COVID-19 and disease X, which represents an infection caused by a pathogen currently unknown to man.
To develop new vaccines for pandemic-causing infections, information about the pathogen and access to the pathogen itself is important. The advancement of technologies and the increased willingness to share important scientific information means that groups around the world can work to develop vaccines more quickly. In 2003, when the Severe Acute Respiratory Syndrome (SARS) started to spread around the world it took approximately 6 months from when the infection first emerged for the full details of the virus to be made available, whereas, for COVID-19 this same process took just weeks.
Accelerated pathways for testing and approvals of new vaccines have been developed with the hope that pandemic vaccines may be available in months and not years. The vaccines still need to go through the necessary testing stages, to ensure that they are safe, but these may happen over a shorter period and not all traditional stages of testing are done.
Large numbers of vaccines are required to help stop a pandemic. It can be challenging to make enough vaccine in time for reasons that include:
- limited availability of materials needed to make vaccines
- manufacturing facilities
For example, traditional influenza viruses are made by growing the virus in hens’ eggs, and the time it takes to do this cannot be sped up. One way this has been overcome is been by developing influenza vaccines that work with a smaller amount of virus. An example of this is a vaccine that was used during the Swine flu pandemic of 2008. It included a novel adjuvant that helps stimulate the immune system, so the vaccine is effective despite containing a smaller amount of virus than other types of influenza vaccine.
A pandemic means there is transmission of infection in countries all around the world. Some countries may have the ability to produce vaccines in their own country whilst most will not. To halt or slow down a pandemic then we need to ensure that all countries have access to vaccines. We will learn more about how this happens in the Swine flu pandemic case study.
In the next few steps we will look at how vaccination has played an important role in controlling some recent pandemics and outbreaks of infectious diseases.