COVID-19 Vaccine

As the new coronavirus continues to cause illness and death around the world, the vaccine is seen as the best way to stop it.

Coronavirus Vaccine Progress

Vaccines are now available for children as young as 5 years old.  These Pfizer-BioNTech COVID-19 vaccines are a third the strength of those which have been authorized in those 12 and older. As in the adult version, the children’s version requires two does, take 3 weeks apart.

A two dose Moderna vaccine is also approved, as is a single dose Johnson & Johnson vaccine.

Booster shots of the Pfizer and Moderna vaccines are recommended for those 65 years and older, 50–64 years with underlying medical conditions, or 18 years and older who live in long-term care settings should receive a booster shot.

A J&J booster is recommended for those 18 years and older should receive a booster shot at least 2 months after receiving their original J&J vaccine.

Initially, health care workers and the elderly were the first to receive the vaccine. But following the success of mass production and distribution, in mid-April, the vaccines were made available to a broader population.

The CDC also says the vaccines are safe for pregnant women and there is no indication they pose any danger to the fetus. There have been reports of adverse allergic reactions to some of the vaccines, so at present time, people who have a history of severe allergies are advised not to get vaccinated

Both the Pfizer and Moderna vaccines have shown over 90% efficacy for adults and require two doses administered several weeks apart. Johnson & Johnson requires just one shot and is 85% effective. China and Russia have both developed their own vaccines that are being used in other countries.

The Pfizer vaccine uses messenger RNA (mRNA). This is what carries the instructions for making the “spike” protein that lets the virus enter human cells. The mRNA vaccine tells your immune cells to make the protein and act as if they’ve already been infected with the coronavirus, giving you some immunity against it.


The J&J vaccine uses DNA that’s designed to trigger an immune response to the virus.

Still another candidate uses the recombinant vesicular stomatitis virus (rVSV), which was used to create the Ebola vaccine.

Several vaccines have weakened versions of the adenovirus, one of the viruses that causes the common cold. It’s been combined with genes from the new coronavirus’ spike protein to trigger your immune system to fight it. 

Yet other vaccines teach your immune system to target the coronavirus by using versions of the spike protein or the virus itself.

This version of the coronavirus only surfaced in late 2019. Normally, developing a new vaccine for a new virus takes years, but scientists were able to get a boost from research on similar coronaviruses that cause severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS).

Experts say this coronavirus could eventually turn out to be seasonal, like colds and the flu. A vaccine would be vital to helping control it.

What Does a COVID-19 Vaccine Do?

When you come into contact with viruses or bacteria, your body’s immune system makes antibodies to fight them off.

A vaccine forces your immune system to make antibodies against a specific disease, usually with a dead or weakened form of the germs. Then, if you come into contact with them again, your immune system knows what to do. The vaccine gives you immunity, so you don’t get sick or so your illness is much milder than it otherwise would have been.

The vaccine should slow the spread of COVID-19 around the world. Fewer people should get sick, and more lives can be saved.

Can You Get the Flu Vaccine and the COVID-19 Vaccine at the Same Time?

Yes. The CDC says you no longer have to wait 14 days between vaccinations. Experts say that after getting the COVID-19 vaccine, your immune response -- the process in which your body builds antibodies to protect you against the virus -- is basically the same whether you take it alone or with the flu vaccine. Flu season in the U.S. typically lasts from October to May.

Possible common side effects like pain, redness, and swelling may last a day or so at the injection site. These won’t change much if you get the flu vaccine, too. Call 911 or head to the nearest hospital if you have a severe allergic reaction.


How Are Vaccines Developed?

The development of a vaccine against COVID-19 has taken place in an unparalleled pace. Usually such a process takes years, but the scope of the pandemic triggered round-the-clock work by thousands of researchers working on over 100 different forms of the vaccine.

Effectiveness and safety were key concerns and the Pfizer vaccine approved in the U.S. for emergency use has been found to have 95% efficacy after its second dose.

Before any vaccine can be used widely, it must go through development and testing to make sure that it’s effective against the virus or bacteria and that it doesn’t cause other problems. The stages of development generally follow this timeline:

  • Exploratory stage. This is the start of lab research to find something that can treat or prevent a disease. It often lasts 2 to 4 years.
  • Pre-clinical stage. Scientists use lab tests and testing in animals, such as mice or monkeys, to learn whether a vaccine might work. This stage usually lasts 1 to 2 years. Many potential vaccines don’t make it past this point. But if the tests are successful and the FDA signs off, it’s on to clinical testing.
  • Clinical development. This is a three-phase process of testing in humans. Phase I usually lasts 1 to 2 years and involves fewer than 100 people. Phase II takes at least 2 years and includes several hundred people. Phase III lasts 3 or 4 years and involves thousands of people. Overall, the clinical trial process may stretch to 15 years or more. About a third of vaccines make it from phase I to final approval.
  • Regulatory review and approval. Scientists with the FDA and CDC go over the data from the clinical trials and sign off.
  • Manufacturing. The vaccine goes into production. The FDA inspects the factory and approves drug labels.
  • Quality control. Scientists and government agencies keep tabs on the drug-making process and on people who get the vaccine. They want to make sure it keeps working safely.

How to Volunteer

If you're interested in volunteering for a COVID-19 vaccine trial, here are some sources for more information: 


Government-sponsored sites:

  • COVID-19 Prevention Network (CoVPN). This is funded by the National Institute of Allergy and Infectious Diseases and coordinated by the Fred Hutchinson Cancer Research Center in Seattle. Its goal is to enroll thousands of volunteers into COVID vaccine trials nationwide. Many research centers are using this site to find volunteers.
  • This is a government database of public and private clinical studies done worldwide. The site also offers considerations for joining a clinical trial.

Sites that link volunteers with trials nationwide include:

Individual hospitals, universities, research centers, and others may also provide opportunities to enroll in a COVID-19 vaccine clinical trial. Some include:

You can also call or visit the website of your local hospital or research institution to find out if it is taking part in any trials.

WebMD Medical Reference Reviewed by Michael W. Smith, MD on November 03, 2021



FDA: “Coronavirus (COVID-19) Update: FDA Authorizes Pfizer-BioNTech COVID-19 Vaccine for Emergency Use in Adolescents in Another Important Action in Fight Against Pandemic.”

Reuters: “Canada allows Pfizer COVID-19 vaccine for children aged 12-15.”

Pfizer: “Pfizer-Biontech Announce Positive Topline Results of Pivotal Covid-19 Vaccine Study in Adolescents.”

CDC: “About Coronavirus Disease 2019 (COVID-19),” “Vaccines: The Basics,” “Vaccine Testing and the Approval Process.”

The History of Vaccines: “Vaccine Development, Testing, and Regulation.”

Biostatistics: “Estimation of clinical trial success rates and related parameters.”

Johns Hopkins University HUB: “What Will It Take to Develop a Vaccine for COVID-19?”

JAMA Network: “Characteristics and Important Lessons from the Coronavirus Disease 2019 (COVID-19) Outbreak in China.”

Children’s Hospital of Philadelphia: “Making Vaccines: Process of Vaccine Development.”

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News release, National Institutes of Health.

Science: “Scientists are moving at record speed to create new coronavirus vaccines -- but they may come too late.”

News release, Moderna.

The Lancet: “COVID-19 vaccine development pipeline gears up.”

News release, Inovio.

News release, University of Oxford.

CDC: “Getting Your COVID-19 Vaccine,” “Possible Side Effects After Getting a COVID-19 Vaccine,” “The Flu Season.”

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