New versions of the two jabs that have been modified to accommodate different variations could also be available in the UK under the terms of the deal announced on Thursday.
Agreements with the two jab makers were speeded up following the discovery of the Omicron variant last week.
Supplies for the current recall campaign have already been secured, but the new agreement adds 114 million more doses to the existing order.
The doses – 60 million Moderna and 54 million Pfizer – will be delivered over the next year and 2023.
If jabs suitable for the variants are produced by either company, Britain will have priority access to them.
The Oxford / AstraZeneca vaccine which provided most of the initial deployment is now unlikely to be used in future campaigns, following evidence that jabs based on mRNA technology are more effective.
News of the deal is likely to exacerbate criticism of the large number of doses ordered by the UK and other Western powers such as the US and the EU as the developing world continues to struggle. to get enough vaccines.
Britain ordered a total of 453.5 million jabs from six different developers and gave 70 million to developing countries.
The deal was secured by the Vaccines Task Force, which works outside normal government structures to make deals directly with drug companies.
Health Secretary Sajid Javid said: “Thanks to the Vaccine Task Force, we have an excellent track record in securing the vaccines the country needs to keep this virus at bay.
“These new agreements will help sustain Britain’s immunization effort – which has so far provided over 115 million first, second and second vaccines across the UK – and ensure we can still protect more people in the years to come. “
The need for annual Covid-19 vaccinations in the future depends on the decrease in immunity over time and whether the current generation of vaccines continue to protect against the newer variants.
Professor Robin Shattock, Imperial College London, is developing RNA vaccine technology, backed by AstraZeneca, which he aims to use for Covid vaccines and, potentially, common Covid and influenza vaccines .
He said is: “As we see more and more variants, it may be necessary to have the equivalent of the influenza vaccine with several strains in its Covid vaccine.
“It’s very difficult to predict. It may be that it calms down and Omicron or Delta will remain the dominant strain … or we may need to develop approaches that give you enough antibodies – so a mix of different strains – so that you are fine. equipped for any type of change.