It’s summer. Most people are thinking about ice cream, baseball and the beach. But, before we know it, school will be back in session and viruses will be more easily shared. Increasingly, fall has become a time to think about vaccines. Influenza, RSV and COVID-19 vaccines all become more top of mind as summer turns into fall and calendars inch closer to the end of the year.
However, to have vaccines in the fall, someone needs to be thinking about them in the summer, particularly for those vaccines that change annually to keep up with evolving viruses. We have been updating influenza vaccines for years, but now, we are also in a situation where COVID-19 vaccines have started to be updated to better match variants of SARS-CoV-2, the virus that causes COVID-19. As newer versions of the virus spread through communities, often referred to as circulating variants, they are tracked so that scientists can determine which ones are causing the most illness.
These findings are then used to update vaccines. This planning is difficult because in the time it takes to go from selecting the variant to producing the vaccine, the virus continues to change. As demonstrated on this image from the Centers for Disease Control and Prevention (CDC), several variants have spread through communities since the start of the pandemic.
SARS-CoV-2 demonstrates the unpredictability of viruses
The difficulty of selecting a vaccine strain of virus was on display during the planning for 2024-2025 COVID-19 vaccines. In early June, the Food and Drug Administration (FDA) met with their advisory committee members to determine which SARS-CoV-2 variant should be used to update COVID-19 vaccines. Two candidate variants, JN1 and KP2, were discussed. The first, JN1, circulated widely earlier in the spring and, as such, was the choice recommended by the World Health Organization (WHO). However, in the weeks leading up to the meeting, KP2 slowly increased its presence in some U.S. communities. Based on these data, the advisory committee recommended JN1. The FDA agreed and provided COVID-19 vaccine manufacturers with this information, so they could begin making vaccines for the fall. However, shortly thereafter, based on more recent data, the FDA revised their instructions to companies, indicating that if possible, they could switch to KP2.
As it turns out, due to manufacturing circumstances, two companies could make the switch (Moderna and Pfizer) and one couldn’t (Novavax). That’s because Novavax (which is a purified protein vaccine) has a longer production cycle (i.e., about six months) than Pfizer and Moderna vaccines (i.e., three months). So, COVID-19 vaccines available in the U.S. this fall will differ as to which variant will be used. The protein-based vaccine, made by Novavax, will use JN1, and the mRNA-based vaccines, made by both Pfizer and Moderna, will use KP2.
What does this mean for people getting vaccinated this fall?
This difference among vaccines may leave some people wondering whether they should favor one version over the other. The good news is that because these two variants are quite similar, it is likely that they will offer similar immunologic protection. As such, people do not need to worry about which version to get based on the variant the vaccine includes.
You can find out more and hear a history of the variants used in COVID-19 vaccines in this video featuring Dr. Paul Offit, Director of the Vaccine Education Center and a current member of the FDA’s advisory committee.
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It’s summer. Most people are thinking about ice cream, baseball and the beach. But, before we know it, school will be back in session and viruses will be more easily shared. Increasingly, fall has become a time to think about vaccines. Influenza, RSV and COVID-19 vaccines all become more top of mind as summer turns into fall and calendars inch closer to the end of the year.
However, to have vaccines in the fall, someone needs to be thinking about them in the summer, particularly for those vaccines that change annually to keep up with evolving viruses. We have been updating influenza vaccines for years, but now, we are also in a situation where COVID-19 vaccines have started to be updated to better match variants of SARS-CoV-2, the virus that causes COVID-19. As newer versions of the virus spread through communities, often referred to as circulating variants, they are tracked so that scientists can determine which ones are causing the most illness.
These findings are then used to update vaccines. This planning is difficult because in the time it takes to go from selecting the variant to producing the vaccine, the virus continues to change. As demonstrated on this image from the Centers for Disease Control and Prevention (CDC), several variants have spread through communities since the start of the pandemic.
SARS-CoV-2 demonstrates the unpredictability of viruses
The difficulty of selecting a vaccine strain of virus was on display during the planning for 2024-2025 COVID-19 vaccines. In early June, the Food and Drug Administration (FDA) met with their advisory committee members to determine which SARS-CoV-2 variant should be used to update COVID-19 vaccines. Two candidate variants, JN1 and KP2, were discussed. The first, JN1, circulated widely earlier in the spring and, as such, was the choice recommended by the World Health Organization (WHO). However, in the weeks leading up to the meeting, KP2 slowly increased its presence in some U.S. communities. Based on these data, the advisory committee recommended JN1. The FDA agreed and provided COVID-19 vaccine manufacturers with this information, so they could begin making vaccines for the fall. However, shortly thereafter, based on more recent data, the FDA revised their instructions to companies, indicating that if possible, they could switch to KP2.
As it turns out, due to manufacturing circumstances, two companies could make the switch (Moderna and Pfizer) and one couldn’t (Novavax). That’s because Novavax (which is a purified protein vaccine) has a longer production cycle (i.e., about six months) than Pfizer and Moderna vaccines (i.e., three months). So, COVID-19 vaccines available in the U.S. this fall will differ as to which variant will be used. The protein-based vaccine, made by Novavax, will use JN1, and the mRNA-based vaccines, made by both Pfizer and Moderna, will use KP2.
What does this mean for people getting vaccinated this fall?
This difference among vaccines may leave some people wondering whether they should favor one version over the other. The good news is that because these two variants are quite similar, it is likely that they will offer similar immunologic protection. As such, people do not need to worry about which version to get based on the variant the vaccine includes.
You can find out more and hear a history of the variants used in COVID-19 vaccines in this video featuring Dr. Paul Offit, Director of the Vaccine Education Center and a current member of the FDA’s advisory committee.