Emerging variants of the virus that cause Covid-19 have caused concern that the vaccines developed so far will not provide the high level of protection seen in clinical trials. Variants have been identified in California, South Africa, Brazil and the United Kingdom.
However, not every variant needs a new vaccine, as vaccines provide a broad immune response that is likely to cover many mutations. Here’s what needs to be done to determine if a vaccine needs to be adapted, and how to adapt it.
Detection To confront a new variant, you must first detect it. Observation is important, so scientists must be constantly vigilant and do international cooperation, as for the flu virus. Manufacturers of approved vaccines – including Pfizer / BioNTech, Moderna and Oxford / AstraZeneca – are looking at ways to improve their vaccines so that they are ready for any variant.
Comparison Once a variant of concern has been identified, scientists need to look at whether the efficacy of the vaccine has decreased significantly. In the case of the variant discovered in the United Kingdom, scientists were confident that the vaccines already available worked well against it, but for the one discovered in South Africa, the data are much less encouraging.
Amendment If an adaptation of the vaccine is required, the technology used in the vaccine determines how quickly and easily the modification can be made. For example, the mRNA vaccines manufactured by Pfizer / BioNTech and Moderna are much easier to adapt than traditional vaccine technologies.
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Production BioNTech said it could produce a fresh vaccine within six weeks of the decision. But the Oxford / AstraZeneca team, which uses more traditional viral vector technology, says while it may make a new formulation within days, it takes much longer to manufacture. It is expected that by autumn there will be a vaccine designed to address the variant discovered in South Africa.
Trials How extensive the trials of modified vaccines should be is unclear. In the case of flu vaccines, regulators do not require large-scale trials, but are content with smaller studies to show that they work as well as the original vaccine. This is probably what is expected of Covid-19 vaccine manufacturers.
Approval The new vaccine must be approved by the regulators. In the UK, the Regulatory Agency (Medicines and Healthcare Products Regulatory Agency) (MHRA) has said it is in talks with vaccine manufacturers about the approval process for a new sting. “We can say at this stage that it is unlikely that a complete new approval process will be needed,” a spokesman said last month. “No vaccine will be allowed in the UK unless the expected standards of safety, quality and efficacy are met.”