Researchers across the globe continue at pace to find safe and effective vaccines to protect populations against the SARS-CoV-2 virus using different platform technologies. It is clear that to overcome the COVID-19 pandemic, more than one vaccine will be needed.
Providing broad equitable access of the COVID-19 vaccines will enable us to truly alter the course of this pandemic and positively impact real-world effectiveness of this unprecedented vaccination programme. As more vaccines are approved around the world, it is important to explore how they may be used in the real-world setting and to study their interchangeability.
Vaccines often require more than one vaccination in the form of an initial prime, followed by a boost.1 This can be achieved by giving the same vaccine multiple times, known as ‘homologous boosting’, or by combining different vaccines targeting the same antigen, known as ‘heterologous boosting’.
Being able to combine different COVID-19 vaccines may be helpful to improved protection and/or to improve vaccine accessibility. This why it is important to explore different vaccine combinations to help make immunisation programmes more flexible, by allowing physicians greater choice at the time of administering vaccines. It is also likely that combining vaccines may lead to improved immunity over a longer-period of time.
The UK government recently announced that it will begin a clinical trial combining adenovirus vaccines with mRNA technology vaccines. AstraZeneca is also considering how it can assess heterologous combinations of different vaccines, working with industry partners, governments and research institutions around the world, and will soon begin exploring with Gamaleya Research Institute in Russia to understand whether two adenovirus-based vaccines can be successfully combined.
Assessing different types of COVID-19 vaccines in combination could help unlock synergies in protection and improve vaccine accessibility and could provide an additional approach to help overcome this deadly virus.
1. Lu S., et al., Heterologous prime-boost vaccination. Current Opinion in Immunology. 2009, 21(3), 346-51.