While researchers are developing and testing vaccines for SARS-CoV-2, the coronavirus that causes COVID-19, the virus is mutating and evolving as it moves from person to person. To understand if those mutations will affect the effectiveness of vaccines, researchers at the Walter Reed Army Institute of Research and the Fred Hutchinson Cancer Research Center analyzed over 18,500 different SARS-CoV-2 genomes. Their findings should be reassuring for vaccine developers (Proc. Natl. Acad. Sci. U.S.A. 2020, DOI: 10.1073/pnas.2008281117).
Not only did the team, led by Morgane Rolland and Kayvon Modjarrad, find that most mutations were rare, but it also determined that the mutations seem to be part of normal random evolution instead of being in response to selection pressure. Mutations acquired under selection pressure, such as to evade human immune responses, could lead to the appearance of new viral strains.
From this work, the researchers found that SARS-CoV-2 is spreading faster than the virus can evolve. The result is that the SARS-CoV-2 viruses circulating the globe are part of a much more homogeneous population than viruses like HIV, which is good news for vaccine developers. The research team says its findings suggest that the vaccines currently being developed should protect against all the SARS-CoV-2 viruses that currently exist, even though those vaccines were developed based on a viral sequence that was published early in the pandemic.