Pulmonary Uptodate

What to know about the different COVID-19 vaccines

Pfizer-BioNTech
It uses a lipid, or a fatty acid, to deliver a piece of the virus’s genetic code. However, it does not contain the virus — rather, it contains a piece of messenger RNA (mRNA) that codes for the virus’s unique spike protein.

The body responds to this spike protein as an intruder and develops the immune reaction it needs to fight it. The vaccine teaches the body how to fight the COVID-19 virus when it encounters the real thing.

The vaccine’s contents leave the body and do not alter a person’s genetic code.

It does not contain:

gelatin
fetal cells
latex
eggs or other common allergens
latex
preservatives
metals
antibiotics
Approval status
The FDA has approvedTrusted Source the vaccine for individuals over the age of 16. It has an emergency use authorization for people over the age of 5 and for booster shots.

Dosage
The initial series is two injections, at least 21 days apart, and a booster requires a third shot.

The dosage is:

Ages 5-11: two 0.2 milliliter (mL) doses
Ages 12-15: two 0.3 mL doses
Ages 16 and older: two 0.3 mL doses
It is safe to mix and match this vaccine with others.

Side effects
The vaccine’s side effects are typically mild, and some people report having more side effects after the second vaccine.

They commonly report cold and flu-like symptoms such as:

fever
headache
muscle aches
soreness at the injection site
nausea
chills
fatigue
The side effects usually disappear within a few days. They happen because of the immune system’s reaction to the injection, so having side effects shows that the vaccine is working.

Efficacy
According to the CDC, the full series of the vaccine is more than 95%Trusted Source effective at preventing laboratory-confirmed COVID-19 infections in adults who are not immunocompromised and have no documented history of a COVID-19 infection.

In children ages 5–15 and people with immunocompromising conditions, the vaccine was at least 90% effective.

Among adults without immunocompromising conditions between March 11 and August 15, 2021, the vaccine offered 88% efficacy against hospitalization. This time period extends into the Delta wave of the pandemic.

Preliminary data from Pfizer showed that three doses of the vaccine could neutralize the Omicron variant.

Other research is still ongoing. A 2022 studyTrusted Source found that in a lab setting, a booster could offer some immunity to Omicron.

Moderna
The Moderna vaccineTrusted Source, also called Spikevax, is an mRNA vaccine

Overview
Although it works similarly to the Pfizer vaccine, it delivers a slightly higher dose.

Like Pfizer, it contains mRNA that gives instructions for fighting the spike protein on the COVID-19 virus. This produces an immune reaction that trains the body to fight the virus if it encounters it in the real world.

The vaccine’s contents leave the body and do not alter a person’s genetic code. It does not contain any of the following:

viruses
bacteria
fetal cells
eggs
preservatives
metals
antibiotics
latex
Approval status
The FDA has approvedTrusted Source the Moderna vaccine for adults ages 18 and over. It also has an emergency use authorization as a one-dose booster 5 months after receiving another vaccine.

Moderna is not approved for use in children.

Dosage
The initial Moderna series requires two injections, with a third shot as a booster.

It has earned an emergency use authorization for people over the age of 18. Each dose is 0.5 mL, and the two shots should be at least 28 days apart.

Like the Pfizer vaccine, it is safe to mix and match this vaccine with others.

Side effects
Because they are both mRNA vaccines, the side effects of Moderna are similar to those of Pfizer.

Some people report mild cold or flu-like symptoms shortly after getting vaccinated with side effects more frequently appearing after the second vaccine than the first. Some common side effects include:

headache
fatigue
chills
fever
body aches
gastrointestinal issues
redness, swelling, and pain at the injection site
Efficacy
Among adults without immunocompromising conditions between March 11 and August 15, 2021, Moderna was 93% effective Trusted Source against hospitalization due to COVID-19. This time frame includes the Delta wave, but not Omicron.

A 2022 study Trusted Source found that an additional Moderna booster dose could provide some immunity against the Omicron variant while the two-dose series did not. Moderna is working on a booster specific to new variants.

Johnson & Johnson
The J&J/Janssen vaccineTrusted Source is a single-shot viral vector vaccine.

Overview
Unlike Pfizer and Moderna, it is not an mRNA vaccine. Instead, it works similarly to traditional vaccines.

The vaccine uses a weakened form of a harmless adenovirus that delivers genetic code for the unique COVID-19 spike protein. This creates an immune reaction that prepares the body to fight COVID-19. The vaccine’s contents leave the body and do not alter a person’s genetic code.

It cannot infect a person with COVID-19 or the adenovirus, and it does not contain:

preservatives
antibiotics
metal
latex
fetal parts
eggs
The injection is generally less effective than the Moderna and Pfizer vaccines.

The CDC urges people to choose the mRNA vaccines unless they are inaccessible. While J&J/Janssen is safer than going unvaccinated, it may have worse side effects than other vaccines.

Approval status
The FDA has approvedTrusted Source the vaccine on an emergency use authorization basis for people over the age of 18. It has also given emergency use authorization for a booster at least 2 months after the first dose.

The vaccine is not approved for children or anyone under the age of 18.

Side effects
The most common side effects of this vaccine include mild cold or flu-like symptoms such as nausea, fever, chills, and muscle aches.

Very rarely, however, a person may develop a blood clot.

The CDC estimates that roughly 3.83 people per millionTrusted Source will have this side effect. However, the blood clot rate is much higher with a COVID-19 infection, with as many as 1 in 5 peopleTrusted Source experiencing a blood clot. Of 18.2 million J&J/Janssen vaccine recipients, just 57, or 1 in more than 300,000Trusted Source, have reported blood clots.

Dosage
The J&J/Janssen vaccine is a single-dose vaccine. It has an emergency use authorization in the United States for people over the age of 18.

A person can also get a single dose booster, but the CDC recommends choosing Pfizer or Moderna instead. It is safe to mix and match this vaccine with others.

Efficacy
Between March 11 and August 15, 2021, a time period that included the Delta wave but not Omicron, the J&J/Janssen vaccine was 71% effective in preventing COVID-19 hospitalization.

Oxford AstraZeneca
The Oxford AstraZeneca vaccine works very similarly to the J&J/Janssen vaccine.

Overview
It uses an adenovirus to deliver the COVID-19 spike protein into the body. This creates an immune reaction that trains the body to fight the virus if it encounters it again.

Approval status
The AstraZeneca vaccine does not have FDA approval in the United States. However, it is popular in Europe because it is less expensive to produce than mRNA vaccines and is easier to store.

Dosage
The World Health Organization (WHO)Trusted Source recommends two doses of 0.5 mL each, and the vaccines should be 8 to 12 weeks apart. It is safe to mix and match this vaccine with others.

Side effects
Some common side effects includeTrusted Source:

fever
chills
muscle aches
flu and cold-like symptoms
pain at the injection site
In rare cases, the AstraZeneca vaccine may cause blood clots. The risk of blood clots from COVID-19 is exponentially higher.

Efficacy
The AstraZeneca vaccine prevents symptomatic infection in 6 out of 10 people. Early trials, prior to Delta and Omicron, showed an 80% efficacy at preventing hospitalization.

Novavax
The Novavax vaccine uses older vaccine technology — specifically, a protein subunit.

Overview
This vaccine delivers an antigen synthesized from the COVID-19 spike protein to train the body to fight the virus. It does not contain a live virus, and the spike antigen cannot replicate.

Approval status
Novavax is not yet approved for use in the U.S., but a request for an emergency use authorization has been submitted. As of November 2021, it is approved for use in Indonesia and the Philippines.

Dosage
The WHO recommendsTrusted Source two 0.5 mL doses given 3–4 weeks apart.

It is safe to mix and match this vaccine with others.

Side effects
Side effects include:

fatigue
headache
fever
muscle pain
injection site swelling, pain, and redness
Efficacy
In clinical trials, the efficacy of Novavax against mild, moderate, and severe disease was 90%Trusted Source. Researchers do not know if it prevents infection or transmission and are conducting additional research.

Here's Why COVID-19 Impacts Your Ability to Smell
A new study finds that damage to nasal tissue may be the reason some people lose their sense of smell after having COVID-19.
Experts say this is actually a good sign because tissue may recover more quickly than nerves.
Smell training is one way people may be able to recover their sense of smell.
One distinctive symptom of COVID-19 remains the loss of sense of smell and taste that can affect people for weeks or months after developing the disease.

The decreased or altered sense of smell, called olfactory dysfunction, was originally thought to be due to damage of the olfactory nerves. But new research published this week in The Laryngoscope Trusted Source finds that loss of smell due to COVID-19 may also be because of swelling and blockage of the nasal passages.

Originally the loss of taste and smell due to COVID-19 was thought to be damage to the olfactory nerve. While evidence was limited for a direct relation between SARS-CoV-2 and abnormal brain findings, the theory was that the olfactory dysfunction was due to the olfactory nerve Trusted Source.

They found a prevalence of an olfactory cleft abnormality. The olfactory. Researchers combed through medical reports that detailed changes in olfactory structures through imaging tests of patients with COVID-19. cleft is the channel through which airborne molecules reach the olfactory neurons, which connect to the brain in order to determine smells. In patients with COVID-19 and olfactory dysfunction, the cleft abnormality was 16 times higher.

This means that a contributing factor of the loss of smell and taste is due to the tissues instead of nerves.
The good news is that cells turn over and heal much more easily than nerve damage.

Can loss of sense of smell and taste be returned?
the symptoms are reversible as time goes on and cells turn over. It’s not permanent.”
and recovery times vary widely from one to three weeks to months or years.

“While there are limited treatment options, people have been using smell training as a treatment option with mixed outcomes.
Smell training involves smelling items like specific scents of items like oranges or coffee grounds.
vaccination may alleviate symptoms but clarified that there is no definitive proof of that yet.

However, it is important to note that the findings may not fully account for people living with the extended loss of sense of smell or taste. More research will have to be conducted.