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We're beyond one year since COVID-19 effectively brought the United States and world to a halt, vaccines are becoming available to more and more of the population.

While these vaccines were created in record time, it does not make them any less safe. Moreso, it is a testament to the advancement of science and technology in modern times.

Vaccine availability varies state to state. To find out if an individual is eligible for a vaccination appointment, contact your state health department.

All COVID-19 vaccines train the body to recognize the new coronavirus, usually by spotting the spikey protein that coats it. But they’re made in very different ways.

Johnson & Johnson’s shot uses a cold virus like a Trojan horse to carry the spike gene into the body, where cells make harmless copies of the protein to prime the immune system in case the real virus comes along. It’s the same technology the company used in making an Ebola vaccine, and similar to COVID-19 vaccines made by AstraZeneca and China’s CanSino Biologics.

The Pfizer and Moderna vaccines are made with a different technology, a piece of genetic code called messenger RNA that spurs cells to make those harmless spike copies.

Below is an overview of the three vaccines that have been approved for emergency use in the United States.


This was the first vaccine approved for emergency use by the FDA after clinical trials showed a 95 percent efficiency rate. It is given in two doses, 21 days apart in the upper area of the arm. It is recommended for ages 16 and over and clinical trials are underway testing the vaccine in kids ages 12 to 15.

Common side effects, according to the CDC, include: Pain, redness and swelling at the injection site. Tiredness, headache, muscle pain ,chills, fever and nausea throughout the rest of the body possible on the day of and couple following days after.

Data relating to how well the Pfizer vaccine works against mutations of the original COVID-19 strain remains ongoing. According to Yale Medicine, the Pfizer vaccine protects against the variant that was found in Great Britain but could be less effective against the variant found in South Africa.

(Related: Pfizer says its vaccine protects teens)



Moderna’s vaccine was authorized for emergency use seven days after Pfizer. During clinical trials, data showed Moderna to be 94.1 percent effective at “preventing laboratory-confirmed COVID-19 illness in people who received two doses who had no evidence of being previously infected.”

Although the percentage dropped and was slightly less effective in people 65 years old and above, coming in with a 86 percent efficiency rate. Moderna is recommended for people 18 and older and testing continues on kids ages 12 to 17. The shot is administered in two doses, 28 days apart, with the injection in the upper part of the arm.

Similarly to the Pfizer vaccine common side effects, according to the CDC, include: Pain, redness and swelling at the injection site. Tiredness, headache, muscle pain ,chills, fever and nausea throughout the rest of the body possible on the day of and couple following days after.

As it relates to mutations of the virus, research is ongoing.


Johnson & Johnson

This is the latest vaccine to be authorized for emergency use and unlike the previously mentioned vaccine versions, it is administered in a single shot in the upper arm. It is currently recommended for those ages 18 and older.

It has the same side effects as the other vaccine shots: Pain, redness and swelling at the injection site, according to the CDC. Tiredness, headache, muscle pain, chills, fever and nausea throughout the rest of the body possible on the day of and couple following days after.

While Pfizer and Moderna had efficacy rates in the mid 90s, data from the CDC shows that the Johnson & Johnson vaccine has an efficiency rate of 66.3 percent. It also states that people had the most protection two weeks after the vaccine was administered and is highly efficient at preventing hospitalization due to the virus.

Early return data also shows the Johnson & Johnson shot provides protection against asymptomatic infection as well.

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How long does protection from COVID-19 vaccines last?

NEW YORK (AP) — How long does protection from COVID-19 vaccines last?

Experts don't know yet because they're still studying vaccinated people to see when protection might wear off. How well the vaccines work against emerging variants will also determine if, when and how often additional shots might be needed.

"We only have information for as long as the vaccines have been studied," said Deborah Fuller, a vaccine researcher at the University of Washington. "We have to study the vaccinated population and start to see, at what point do people become vulnerable again to the virus?"

So far, Pfizer's ongoing trial indicates the company's two-dose vaccine remains highly effective for at least six months, and likely longer. People who got Moderna's vaccine also still had notable levels of virus-fighting antibodies six months after the second required shot. 

Antibodies also don't tell the whole story. To fight off intruders like viruses, our immune systems also have another line of defense called B and T cells, some of which can hang around long after antibody levels dwindle. If they encounter the same virus in the future, those battle-tested cells could potentially spring into action more quickly. 

Even if they don't prevent illness entirely, they could help blunt its severity. But exactly what role such "memory" cells might play with the coronavirus -- and for how long -- isn't yet known.

While the current COVID-19 vaccines will likely last for at least about a year, they probably won't offer lifelong protection, as with measles shots, said Dr. Kathleen Neuzil, a vaccine expert at the University of Maryland School of Medicine. 

"It's going to be somewhere in the middle of that very wide range," she said.

Variants are another reason we might need an additional shot.

The current vaccines are designed to work against a particular spike protein on the coronavirus, said Mehul Suthar of the Emory Vaccine Center. If the virus mutates enough over time, vaccines might need to be updated to boost their effectiveness.

So far, the vaccines appear protective against the notable variants that have emerged, though somewhat less so on the one first detected in South Africa.

If it turns out we need another shot, a single dose could extend protection of the current shots or contain vaccination for one or more variants.

The need for follow-up shots will also depend partly on the success of the vaccination push globally, and tamping down transmission of the virus and emerging variants.

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The Associated Press contributed to this report.