What is SARS-CoV-2 COVID-19 mRNA Vaccine (Pfizer): Uses, Dosage, Side Effects and More

The Pfizer COVID-19 vaccine is an mRNA vaccine that helps protect you against severe illness from COVID-19. It works by teaching your immune system to recognize and fight the virus that causes COVID-19, giving your body a head start if you're ever exposed to the real thing.

This vaccine has been thoroughly tested and approved by health authorities worldwide. It represents a breakthrough in vaccine technology, using messenger RNA to deliver instructions to your cells safely and effectively.

What is the SARS-CoV-2 COVID-19 mRNA Vaccine (Pfizer)?

The Pfizer COVID-19 vaccine is an mRNA vaccine developed by Pfizer-BioNTech to prevent COVID-19 disease. mRNA stands for messenger RNA, which is a type of genetic material that gives your cells instructions on how to make a protein.

This vaccine contains a piece of mRNA that instructs your cells to make a harmless piece of the "spike protein" found on the surface of the COVID-19 virus. Once your cells make this protein, your immune system recognizes it as foreign and creates antibodies to fight it.

The vaccine doesn't contain any live virus and cannot give you COVID-19. Instead, it's like showing your immune system a wanted poster of the virus so it can recognize and fight the real thing later.

What is the Pfizer COVID-19 Vaccine Used For?

The Pfizer COVID-19 vaccine is used to prevent COVID-19 disease in people 6 months and older. It's designed to reduce your risk of getting severely ill, being hospitalized, or dying from COVID-19.

The vaccine is particularly important for protecting vulnerable populations, including older adults and people with underlying health conditions like diabetes, heart disease, or compromised immune systems. Even if you do catch COVID-19 after vaccination, you're much less likely to experience severe symptoms.

Healthcare workers, essential workers, and people who are frequently exposed to others also benefit significantly from this protection. The vaccine helps create community immunity when enough people are vaccinated.

How Does the Pfizer COVID-19 Vaccine Work?

The Pfizer vaccine works by training your immune system to recognize and fight the COVID-19 virus. It's considered a highly effective vaccine, with studies showing over 90% effectiveness at preventing severe disease.

When you receive the vaccine, the mRNA enters your muscle cells and instructs them to make the spike protein. Your immune system then recognizes this protein as foreign and produces antibodies and activates other immune cells to fight it.

This process creates immunological memory, meaning your body remembers how to fight the virus if you encounter it later. The mRNA itself breaks down quickly and doesn't stay in your body long-term.

The vaccine typically provides strong protection within about two weeks after your final dose. However, immunity can wane over time, which is why booster doses are recommended.

How Should I Take the Pfizer COVID-19 Vaccine?

The Pfizer COVID-19 vaccine is given as an injection into the muscle of your upper arm. You don't need to take it with food or water since it's administered by a healthcare professional.

You can eat normally before and after your vaccination appointment. There's no need to fast or avoid certain foods. However, it's a good idea to stay well-hydrated and get a good night's sleep before your appointment.

The injection itself takes just a few seconds, and you'll be monitored for 15-30 minutes afterward to watch for any immediate reactions. Most people can resume normal activities right after their vaccination.

If you're taking any medications, you generally don't need to stop them before vaccination. However, discuss any concerns with your healthcare provider, especially if you're on blood thinners or immunosuppressive medications.

How Long Should I Take the Pfizer COVID-19 Vaccine For?

The Pfizer COVID-19 vaccine is given as a series of shots rather than taken continuously like daily medications. The initial series typically consists of two doses given 3-8 weeks apart for people 5 years and older.

For children 6 months to 4 years old, the primary series consists of three doses. The second dose is given 3-8 weeks after the first, and the third dose is given at least 8 weeks after the second.

Booster doses are recommended to maintain protection as immunity naturally decreases over time. Most people should get a booster shot 2-6 months after completing their primary series, depending on their age and risk factors.

Your healthcare provider will help you determine the right timing for your vaccines based on current recommendations and your individual health situation.

What Are the Side Effects of the Pfizer COVID-19 Vaccine?

Most people experience mild to moderate side effects after receiving the Pfizer COVID-19 vaccine. These are actually good signs that your immune system is responding to the vaccine and building protection.

The most common side effects you might experience include pain, redness, or swelling at the injection site. These local reactions typically appear within hours of vaccination and resolve within a few days.

You may also experience some general side effects as your body builds immunity:

• Fatigue or tiredness
• Headache
• Muscle pain
• Chills
• Fever
• Nausea
• Joint pain

These symptoms usually start within a day or two of vaccination and typically last 1-3 days. They're often more noticeable after the second dose.

While concerning, some rare but serious side effects have been reported. These include severe allergic reactions (anaphylaxis), which occur in about 2-5 cases per million doses. Myocarditis and pericarditis (inflammation of the heart muscle or lining) have been reported, particularly in young men, but these cases are typically mild and resolve with treatment.

Very rarely, some people may experience lymph node swelling, which can last several weeks. This is a normal immune response but may be mistaken for other conditions during medical exams.

Who Should Not Take the Pfizer COVID-19 Vaccine?

Most people can safely receive the Pfizer COVID-19 vaccine, but there are some exceptions. You should not get this vaccine if you've had a severe allergic reaction to any component of the vaccine or to a previous dose.

People with a history of severe allergic reactions to vaccines or injectable medications should discuss the risks and benefits with their healthcare provider. You may still be able to receive the vaccine with special precautions and monitoring.

If you're currently sick with COVID-19 or have symptoms, you should wait until you've recovered and completed your isolation period before getting vaccinated.

People with certain medical conditions should consult their healthcare provider before vaccination:

• Those with compromised immune systems
• People taking immunosuppressive medications
• Individuals with autoimmune disorders
• Those with bleeding disorders or taking blood thinners
• People with a history of heart problems, especially young men considering the small risk of myocarditis

Pregnancy and breastfeeding are not contraindications to vaccination. In fact, vaccination during pregnancy can provide protection to both mother and baby.

Pfizer COVID-19 Vaccine Brand Names

The Pfizer COVID-19 vaccine is marketed under the brand name Comirnaty for people 12 years and older. For children 6 months to 11 years, it's available under specific pediatric formulations.

You might also hear it referred to as the Pfizer-BioNTech vaccine, recognizing both companies involved in its development. Healthcare providers may also call it the "Pfizer mRNA vaccine" or simply "Pfizer COVID vaccine."

Different formulations exist for different age groups, with varying concentrations of the active ingredient. Your healthcare provider will ensure you receive the appropriate formulation for your age.

Alternatives to the Pfizer COVID-19 Vaccine

Several other COVID-19 vaccines are available as alternatives to the Pfizer vaccine. The Moderna COVID-19 vaccine is another mRNA vaccine that works similarly to Pfizer and has comparable effectiveness.

The Johnson & Johnson (Janssen) COVID-19 vaccine uses a different technology called viral vector. It was initially given as a single dose, though boosters are now recommended.

Other vaccines like Novavax use protein subunit technology and may be options for people who cannot receive mRNA vaccines. Your healthcare provider can help you choose the best option based on your age, health conditions, and availability.

In most cases, any authorized COVID-19 vaccine is better than no vaccine. The important thing is getting vaccinated rather than waiting for a specific brand.

Is Pfizer Better Than Moderna COVID-19 Vaccine?

Both Pfizer and Moderna COVID-19 vaccines are highly effective mRNA vaccines with very similar performance. Studies show both provide excellent protection against severe COVID-19, hospitalization, and death.

The main differences are relatively minor. Moderna may provide slightly longer-lasting immunity, while Pfizer has more extensive data in children since it was authorized for younger age groups first.

Side effect profiles are very similar between the two vaccines, though some studies suggest Moderna may cause slightly more arm pain and fatigue. Both have the same rare risk of myocarditis in young men.

From a practical standpoint, the best vaccine is the one that's available to you when you need it. Both are excellent choices, and you shouldn't delay vaccination to wait for a specific brand.