However, creating avaccinewas a massive task because researchers initially knew little about the virus.
Also, at first, it wasnt even clear if a vaccine would be possible.
Since that time, researchers have made unprecedented strides.
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They have designed several vaccines in a much faster time frame than has ever been done before.
This article explains vaccine development, the different types of COVID-19 vaccines, and how they work.
It also covers why a variety of COVID-19 vaccine types is beneficial.
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General Vaccine Development Process
Vaccine development proceeds in a careful series of steps.
These detailed processes ensure the final product is both safe and effective.
Research and Vaccine Trials
First comes the phase of basic research and preclinical studies in animals.
After that, vaccines enter small phase 1 studies, focusing on safety.
Then, more extensive phase 2 studies focus on effectiveness.
The agencies lifted the pause after conducting a safety review.
They also added information about the rare condition to fact sheets for healthcare professionals and people receiving the vaccine.
Prioritywent to certain people, such as frontline workers.
In the U.S., everyone 6 months and older is eligible for a COVID-19 vaccine.
The updated schedules including COVID-19 vaccines were then published in February 2023.
Their mRNA vaccine received emergency use authorization for people 16 and older on December 11, 2020.
This was based on data from its phase 3 trials.
The initial doses of the Pfizer vaccine are two 30 microgram (mcg) doses spaced 21 days apart.
The vaccine is marketed under the nameComirnaty.
The composition of the vaccine has been updated since the initial version.
The vaccine is now marketed asSpikevax.
All individuals 6 months and older are now eligible to receive a Moderna vaccine.
As with the Pfizer vaccine, updated versions have since been created targeting the predominant virus strains in circulation.
Updated vaccines have been authorized each year since, targeting the predominant omicron variant.
The J&J vaccine differs from Pfizer and Moderna because it is a single-dose, viral vector vaccine.
AstraZeneca
AstraZeneca’s vaccine is approved or authorized for emergency use in over 100 countries.
However, it is not FDA-approved for any use in the U.S.The vaccine is marketed as Vaxzevria.
The following month, Moderna’s vaccine was also granted EUA for use as a booster.
The CDC recommends that everyone age 6 months and older receive an updated vaccine.
Those who are immunocompromised may receive additional doses.
How Do Vaccines Work?
All the vaccines designed to target COVID-19 have some similarities.
All are made to help people develop immunity to the virus that causes the symptoms of COVID-19.
Immune System Activation
To design effective vaccines, researchers leverage the natural powers of the bodysimmune system.
The immune system works to identify and eliminate infectious organisms (such as viruses) in the body.
T cells identify specific proteins on the virus, bind them, and ultimately kill the virus.
B cells perform critical functions in makingantibodies, small proteins that also neutralize and destroy the virus.
Thats one reason it takes you a while to get better after becoming sick.
This amount is not enough to make you ill.
The available COVID-19 vaccines differ in how they interact with the immune system to get this protective immunity going.
Both the Pfizer and Moderna vaccines utilize this newer technology.
Then the persons cells use this genetic information to produce the actual protein.
This approach sounds a lot scarier than it is.
So, theres no possibility of being infected and getting sick from aDNA or mRNA vaccine.
That will activate your immune system to start forming a protective immune response.
The same is true of DNA-based vaccines, although some of these have been approved for veterinary uses.
They just use a different mode of getting the viral genetic material into a person’s cells.
The Johnson & Johnson vaccine uses viral vector technology.
Viral vector vaccines use part of adifferentvirusone genetically modified not to be infectious.
Viruses are particularly good at getting into cells.
Researchers have more experience with viral vector vaccines than new approaches such as those based on mRNA.
Neither vaccine is available in the United States.
Live Virus Vaccines
A live virus vaccine uses a weakened virus to produce an immune response.
These vaccines use classic technology.
None of the U.S.-approved COVID-19 vaccines use this kind of technology.
Alive virus vaccineuses a still active and alive virus to provoke an immune response.
However, the virus has been altered and severely weakened so that it causes few if any symptoms.
These vaccines are also called live-attenuated vaccines.
Because they still have a live virus, these vaccines require more extensive safety testing.
In addition, they tend to provoke a robust immune response that lasts a long time.
In addition, they may be more likely to cause significant adverse events than those made by other methods.
COVID-19 Vaccines in Development
None of the U.S.-approved COVID-19 vaccines use live virus technology.
Inactivated Virus Vaccines
Inactivated virus vaccines use a killed virus to produce an immune response.
These are also classic vaccines.
None of the U.S.-approved COVID-19 vaccines use this technology.
Then the dead,inactivatedvirus is injected into the body.
But they both have well-established pathways for product development and manufacturing.
Inactivated virus vaccines are safer and more stable to work with than live-virus vaccines.
Vaccines using inactivated viruses usually require multiple doses, and they may require repeat booster doses over time.
They may also not provoke quite as strong a response as a live vaccine.
Several COVID-19 vaccines made using this approach have been approved outside of the U.S., like Sinovac’s CoronaVac.
However, there have been some newer innovations within this category.
The Novavax, Adjuvanted vaccine is the first protein-based COVID-19 vaccine authorized in the U.S.
Instead of using inactivated or weakened viruses, these vaccines use apartof a pathogen to induce an immune response.
Scientists carefully select a small part of the virus that will best get the immune system going.
For COVID-19, this means a protein or a group of proteins.
There are many different types of subunit vaccines, but all of them use this same principle.
Protein-based subunit vaccines can’t cause any active infection.
For example, the first vaccines against pertussis in the 1940s used inactivated bacteria.
Later, pertussis vaccines used a subunit approach.
These were much less likely to cause significant side effects.
Another advantage of the protein subunit vaccines is that they have been around longer than newer vaccine technologies.
Their track record means that their safety is better established overall.
Also, they may take longer to develop than vaccines using newer technologies.
The Benefits of Various COVID-19 Vaccine Technologies
Ultimately, its helpful to have multiple safe, effectivevaccinesavailable.
Therefore, it will be much easier to perform widespread vaccination if several safe and effective vaccines are produced.
Some require specificstorage conditions, like freezing.
And some will be more expensive than others.
Some might be better for specific populations, like the elderly or people with certain medical conditions.
For example, live virus vaccines will probably not be advised for anyone with problems with their immune system.
In the U.S., updated COVID-19 vaccines are open to everyone over 6 months old.
Globally, even more vaccines are available, and more are in the development and trial phases.
Vaccines do not all use the same technology.
Some utilize a live or inactivated virus.
Others use protein-based subunits.
Still others use DNA, mRNA, or viral vectors.
The U.S.-approved COVID-19 vaccines use mRNA or protein subunit technology.
For the most recent updates on COVID-19, visit ourcoronavirus news page.
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