COVID-19 vaccines first became available in December 2020.
Like most vaccines, the COVID-19 vaccines work in more than one way to prevent infection.
The first involves the production of antibodies.
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Because SARSCoV2 was a new virus, human bodies had not developed an antibody defense for it.
The vaccines help it to achieve that.
These are immune cells that store information for future reference.
This ability is called immunological memory.
However, immunity does wane.
Your individual response and other factors contribute to this loss of protection.
This article explores research on the vaccines and what is known about the immunity they provide.
Here’s how each of the current vaccines works.
Pfizer-BioNTech Vaccine
Pfizer-BioNTech is an mRNA vaccine, based on a newerapproach to making vaccines.
It relies on the power ofnucleic acidsfound in genetic material, butnotthe DNA that is uniquely yours.
Here’s what is known about how long it will work to offer immunity.
When Does It Start Working?
The original Pfizer vaccine was given in two doses scheduled three weeks apart.
The data suggest that after the first dose, some immune response is present in about two weeks.
How Long Does Immunity Last?
These results showed the vaccine was 100% effective against COVID-19.
Further research on the Pfizer vaccine supports its effectiveness.
The vaccine’s formula has been updated and authorized every year to more closely match the dominant COVID-19 variant.
The 2024-2025 formula authorized in August 2024 targets the KP.2 Omicron variant.
Prior to this approval, it had been authorized for emergency use in the U.S. since December 2020.
The vaccine was later authorized for use in individuals 6 months through 17 years of age.
Like Pfizer, it is an mRNA vaccine but there are a few differences.
Moderna has since updated the formula of its vaccine to provide better protection against newer variants of the virus.
The Moderna vaccine was also originally given in two doses.
Both are needed to be considered fully vaccinated.
People who receive this vaccine need to schedule their second dose four weeks after the firstand no sooner.
Full protection is achieved two weeks after the second dose, but some protection occurs earlier.
A document filed with the FDA shows an overall efficacy of 50.8% between days one and 14.
How Long Will Immunity Last?
According to the CDC, updated COVID-19 vaccines can provide protection for several months.
The updated 2024-2025 formula targets the KP.2 Omicron variant.
As with the mRNA vaccines, the Novavax vaccine has been updated annually to match newer variants.
Research suggests that the Novavax vaccine is just as safe and effective as the Pfizer-BioNTech and Moderna COVID-19 vaccines.
This is common for viruses, but some changes have greater impact than others.
In late 2021, the Omicron became the dominant variant and was considered a variant of concern.
Omicron subvariants remain the dominant strain of the virus.
In a December 2021 update, the CDC said it fully expectedbreakthrough infectionseven among the fully vaccinated.
Early evidence suggested that vaccinated people can still spread the Omicron variant.
However, the existing vaccines were still expected to protect against serious illness and death.
Since then, both the 2023-2024 and 2024-2025 formulas of each vaccine have targeted Omicron subvariants.
The FDA is clear that there is not yet enough data to definitively answer the question.
However, for many people, vaccination can provide months of protection.
Years after the pandemic started, there has been much progress.
Just as the virus changes over time, so does the global response to it.
For the most recent updates on COVID-19, visit ourcoronavirus news page.
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Published 2024 Feb 29. doi:10.15585/mmwr.mm7308a5
