Emerging variants of the virus that causes Covid-19 have raised concerns that the vaccines developed to date do not provide the high level of protection seen in clinical trials. Variants have been identified in California, South Africa, Brazil and the UK.
But not every variant needs a new vaccine, as vaccines produce a broad immune response that is likely to include many mutations. Here’s what needs to be done to assess whether a vaccine needs to be modified and how it should be modified.
Detection To confront a new variant, you must first detect it. Surveillance is key, so scientists need to be constantly vigilant and collaborate internationally, just like with the flu virus. Approved vaccine manufacturers – including Pfizer / BioNTech, Moderna and Oxford / AstraZeneca – are exploring ways to improve their vaccines so they are ready for any variant.
Comparison Once a variant of concern has been identified, scientists need to check whether the existing vaccine efficacy has diminished significantly. In the case of the variant discovered in the UK, scientists were convinced that the vaccines already available worked well against it, but for the one discovered in South Africa, the data is much less encouraging.
Modification If the vaccine needs to be modified, the technology used in the vaccine will determine how quickly and easily the change can be made. For example, the mRNA vaccines made by Pfizer / BioNTech and Moderna are much easier to adapt than traditional vaccine technologies.
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production BioNTech has said it can produce a new vaccine within six weeks of making a decision. But the Oxford / AstraZeneca team, which uses more traditional viral vector technology, say that while it can make a new formulation in days, it takes much longer to produce. It expects to have a vaccine designed to target the variant discovered in South Africa in the fall.
taste It is unclear how extensive the trials with modified vaccines will have to be. In the case of flu vaccines, regulators do not need large-scale studies, but are happy with smaller studies to show that they work just as well as the original vaccine. This is likely what is expected from the makers of Covid-19 vaccines.
Approval The new vaccine must be approved by regulators. In the UK, the Medicines and Healthcare products Regulatory Agency (MHRA) has said it is in talks with vaccine manufacturers about the approval process for a new shot. “We can say at this stage that it is unlikely that a completely new approval process will be required,” a spokesman said last month. “No vaccine will be authorized for delivery in the UK unless the expected standards of safety, quality and effectiveness are met.”