Creating vaccines to help fight constantly changing threats

Viruses tend to change through mutation. The more people who are infected by a virus, the more likely it is to mutate and form a new variant.1 This happens to all viruses, and at different rates, depending on their biology.2

The rise of a variant

A different variant of the influenza virus appears every year, primarily during the winter months. Sometimes this variant is relatively similar to the virus from the previous year; however, occasionally a human influenza virus mixes with an influenza virus from another species, for example, pigs, birds, or bats, and creates a markedly different variant. If this happens, the new variant may not be recognized by the immune system and may cause more severe disease. This is what happened during the influenza epidemics of 1957, 1968, and 2009.3–5

9 icons representing genetic drift. Genetic drift. ATCG. ATGG. TACC. Changes to genetic material (DNA) accumulate over time.


Two sources of genetic DNA leading to one source. Mixing genetid materials from two different sources results in a new strain.

Influenza variants are carefully tracked by scientists, who aim to predict the most prominent variant for the coming influenza season so that a vaccine can be designed and produced to specifically immunize against that variant.3,4

Scientists are also closely monitoring the spread of SARS-CoV-2 variants that have been continuously emerging, and are working together around the world to track the changes to the virus and monitor how effective the current vaccines are at protecting against each new variant.6,7

Since its emergence in late 2019, the virus that causes COVID-19 (SARS-CoV-2) has had a devastating impact, resulting in millions of deaths worldwide.8 As the virus has traveled around the globe and passed from person to person, mutations in its genetic code have given rise to different variants of the virus, some of which are more contagious than others and cause more severe disease.1

These variants were originally named according to the country in which they were first detected, but are now named using the Greek alphabet—a different letter is given to each variant: for example, alpha and delta.1

Global SARS-CoV-2 evolution9—each color represents a different variant; the naming has been suggested to signify the year in which the variant emerged (eg, 19A relates to the first variant group detected in 2019, etc).

Graph showing the emergence of five global sars-cov-2 variants from January 2020 to March 2021

Vaccines vs variants

It is important that vaccines may help protect against the most common variants of a virus, including any that might appear in the future, by generating broadly protective antibodies— especially during an epidemic or pandemic13. Vaccines need to be able to train the immune system to generate a broad and robust immune response10 against the random changes in genetic composition (genetic drift) viruses tend to undergo,11 so that it can recognize and help protect against as many variants as possible.11 Without this, the virus could spread further and people could be left unprotected as more variants emerge.13

An adaptable protein-based technology platform

In the face of constant SARS-CoV-2 viral evolution, Novavax vaccine technology is readily adaptable. If a new variant appears and our existing vaccine does not provide sufficient protection, we don’t need to start from the beginning and design an entirely new vaccine. We just need to know how the variant protein sequence differs from the original one—information that is usually available as new variants are detected. Through use of the same genetic engineering techniques, we can adapt our vaccine to work with the variant version of the protein, which can better address a shifting threat. This cost- and time-effective approach to vaccine development and production is at the heart of our nanoparticle technology.

For more information about our technology platform, visit our technology.

  1. Tracking SARS-CoV-2 variants. World Health Organization (WHO). Available at: [Accessed 27 Aug 2021].
  2. Sanjuán R, Domingo-Calap P. Cell Mol Life Sci. 2016;73(23):4433–4448.
  3. Manzanares-Meza LD, Medina-Contreras O. Bol Med Hosp Infant Mex. 2020;77(5):262-273.
  4. Petrova VN, Russell CA. Nat Rev Microbiol. 2018;16(1):47–60.
  5. Influenza virus biology and epidemiology. National Center for Biotechnology Information. Available at:,human%20and%20many%20other%20animals [Accessed 27 Aug 2021].
  6. Giovanetti M, et al. Biochem Biophys Res Commun. 2021;538:88–91.
  7. Vaccine efficacy, effectiveness and protection. WHO. Available at: [Accessed 29 Jul 2021].
  8. WHO coronavirus (COVID-19) dashboard. WHO. Available at: [Accessed 27 Aug 2021].
  9. Singh D, Yi SV. Exp Mol Med. 2021;53(4):537–547.
  10. Bates TA et al. Vaccination before or after SARS-Cov-2 infection leads to robust humoral response and antibodies that effectively neutralize variants. Sci. Immunol. 2022 Oct.
  11. Krammer F. Nat Rev Immunol. 2019;19(6):383–397.
  12. Woodruff M. Immune interference – why even “updated” vaccines could struggle to keep up with emerging coronavirus strains. The Conversation. Available at: [Accessed 27 Aug 2021].
  13. Kang C et al. Broad humoral and cellular immunity elicited by one-dose mRNA vaccination 18 months after SARS-CoV-2-infection. BMC Medicine. 2022 20:181
  14. Mistry P. et al. SARS-CoV-2 Variants, Vaccines and Host Immunity. Frontiers in Immunology. 2022 Jan;10.3389
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