After more than a year of mask-wearing, physical distancing from friends and family, and frequent handwashing and disinfecting, an effective vaccine has arrived. Finally, there’s a light at the end of the COVID-19 tunnel.

The COVID-19 vaccine helps your body develop antibodies that make you less susceptible to the disease.

While it will take months to roll out to the general public and we’ll need to continue following the precautions we’ve come to know well, the vaccine offers hope to protect you and everyone around you, and diminish the risk of exposure.

When it’s your turn to get the vaccine, what can you expect? Which vaccines are available? When does protection against COVID-19 begin after vaccination?

We’ll answer these questions so you can make an informed decision. Also, check the Centers for Disease Control and Prevention (CDC) for the latest information.

How will I know when I’m eligible to receive the vaccine?
Initially the supply of COVID-19 vaccines was severely limited and distributed in phases, starting with healthcare workers and residents of nursing homes (1A), followed by those over 65 and certain frontline essential workers (1B), those age 16-64 with certain medical conditions (1B+), followed by an expanded list of essential workers (1C), and finally anyone else age 16 and older. The supply of vaccine is rapidly increasing. Nationally, all Americans age 16 and over will be eligible by May 1 and there should be enough supply for everyone to receive vaccine by the end of the summer. The state of Illinois expects to expand eligibility to everyone over age 16 beginning April 12. However, the timeline in each county may differ depending on local allocations.

Will I need more than one dose?
For the two mRNA vaccines, yes. The Pfizer-BioNTech vaccine, which was approved for emergency use, requires two doses, separated by 21 days. The vaccine produced by Moderna (also approved for emergency use) also requires two doses, separated by 28 days. The first shot starts building protection and the second shot strengthens the immune response. Both doses are necessary to achieve each vaccine’s full effectiveness. The vaccines are not interchangeable, so individuals should complete the second dose with the same vaccine. The third vaccine, the Janssen (J&J) COVID-19 vaccine, is administered as a single dose, so a second dose is not needed.

Will I need this vaccine every year?
Scientists are still studying this and will make a determination once the vaccine is distributed and more data is available.

Who will administer the vaccines?
Vaccines are distributed by the state to local health departments, pharmacies, hospitals, and mass vaccination clinics. Try this vaccine finder tool, Illinois vaccination locations site, and the CDC more information.

Which vaccines are available?
In December 2020, the Food and Drug Administration (FDA) issued emergency use authorization (EUA) for two COVID-19 vaccines, one manufactured by Pfizer-BioNTech (ages 16 and up) and another by Moderna (ages 18 and up). In February 2021, the FDA issued an EUA for a third COVID-19 vaccine, manufactured by Janssen Pharmaceutical Companies of Johnson & Johnson (ages 18 and up). EUA is an authorization process used by the FDA if there is an emergency and enough evidence that the vaccine will be safe and helpful. Vaccines authorized for EUA still need to meet the FDA's rigorous standards for safety, effectiveness and quality. Several other vaccines are also in development.

How does the vaccine work?
The COVID-19 vaccines train the body’s immune system so it will be ready to fight the virus if you are exposed. The Pfizer-BioNtech and Moderna mRNA 1273 are mRNA vaccines. They contain the portion of mRNA (molecule that carries a genetic code) that sends the body’s cells instructions to make a harmless piece of spike protein, the button on the surface of the SARS-CoV2 virus. It is not a live virus, cannot replicate itself and is quickly destroyed in the cell shortly after translation. Once the spike protein is translated by the mRNA, an immune response is elicited, resulting in the production of antibodies against the spike protein. When the SARS-CoV2 spike protein is bound up by antibodies, it cannot attach to and infect human cells.

The Janssen (J&J) vaccine is a vector vaccine that uses an adenovirus (a type of virus that causes the common cold, not the virus that causes COVID-19) that has been genetically modified to make it harmless, to instruct the body’s cells to make the SARS CoV-2 spike protein. Our immune system recognizes the threat and begins producing antibodies to fight off what it thinks is an infection. This trains the body's immune system to protect against an actual SARS-CoV-2 infection. The virus used in a vector vaccine has been modified so it can’t replicate itself or cause infection.

Is the vaccine safe?
Yes, COVID-19 vaccines in the U.S. are authorized after meeting rigorous scientific standards for safety. The vaccines were evaluated in tens of thousands of participants in clinical trials. The first authorized COVID-19 vaccine, an mRNA vaccine manufactured by Pfizer-BioNTech, was studied in more than 40,000 people, to ensure they meet safety standards. The third authorized vaccine, an adenovirus vector vaccine, is held to the same rigorous safety and effectiveness standards as all other types of vaccines in the U.S. The FDA will continue to monitor the safety and effectiveness of authorized vaccines through ongoing clinical trials and vaccination data.

What’s the difference between the vaccines?
Currently, three vaccines, Pfizer-BioNTech, Moderna and Janssen (J&J) are authorized and recommended to prevent COVID-19.

Pfizer-BioNTech and Moderna are both mRNA vaccines. At this point, one mRNA vaccine is not recommended over the other as both show similar efficacy. One difference is in how the vaccines are stored. While both vaccines need to be kept cold, the Moderna vaccine must be stored at a temperature of a regular refrigerator freezer and can be used within 30 days after thawing, while the Pfizer vaccine requires special ultra-cold freezers and must be used with five days after thawing.

The Janssen (J&J) vaccine is an adenovirus vector vaccine, and can be stored in a refrigerator, instead of a freezer, for up to three months. While direct comparisons can’t be made since the vaccine trials were conducted differently, all three COVID-19 vaccines are highly effective against severe outcomes such as hospitalization and death. At this point, one vaccine is not recommended over the other. At this point, one vaccine is not recommended over the other.

Which vaccine is the most effective?
Both the Pfizer-BioNTech and Moderna vaccines were more than 94 percent effective in preventing symptomatic coronavirus infection (Pfizer's is at 95 percent while Moderna's is 94.1 percent), and nearly 100 percent effective in preventing severe illness from COVID-19. In phase one and two trials, two doses of mRNA were given to hundreds of subjects and elicited neutralizing and binding antibodies in all participants. Antibody levels were higher than the 50^th percentile of patients who had natural infection, in both young adults and the elderly. The vaccines were both effective for different races and genders, as well as for people with underlying medical conditions.

In clinical trials in the U.S., the Janssen (J&J) vaccine was 72% effective in preventing moderate to severe COVID-19 and 86% effective in preventing severe illness from COVID-19. In clinical trials worldwide, the vaccine was 93% effective in preventing severe disease requiring hospitalization from COVID-19 and 100% in preventing COVID-19 deaths. While direct comparisons can’t be made since the vaccine trials were conducted differently, all three COVID-19 vaccines are highly effective against severe outcomes such as hospitalization and death.

Can I choose which vaccine to get?
Which vaccine you receive depends on supply and where you decide to get the vaccine. Experts recommend getting the vaccine that’s available to you.

How long will it take after I get my shot to be protected from COVID-19?
Those who receive the two-dose COVID-19 vaccine will develop maximum immunity several weeks after the second dose. It normally takes about two weeks for cellular immunity to develop and several weeks for full antibody development. For the one-dose Janssen (J&J) vaccine, full protection occurs two weeks after vaccination.

Does the vaccine protect others?
The more people who get vaccinated, the fewer people will spread the virus, the less effectively the virus can transmit, and the better for herd immunity. It’s not yet clear whether vaccinated people could still develop asymptomatic infections and therefore be able to spread the virus to others.

Will I experience any side effects after getting the vaccine?
As with other vaccines, it is normal to experience some fatigue, muscle aches, headaches or low-grade fever following the vaccination. Side effects could also include pain, redness or swelling at the injection site, chills, joint pain, nausea and swollen lymph nodes. Side effects may be more frequent after the second dose and less common among older adults. The side effects are a sign your body is mounting a defense against the disease. The vaccine does not use live or weakened virus, so it cannot give you COVID-19.

Once I’ve had a vaccine, can I stop wearing masks?
No, you should continue to wear a mask after receiving the vaccine. Until you have full immunity, two weeks after receiving the second dose of a two-dose series, or two weeks after one dose of a one-dose series, you are still susceptible. The CDC recommends that everyone continue to wear masks in public. However, CDC guidance allows for some lifting of restrictions when fully immunized individuals are together, or if fully immunized individuals are with others of the same household. It will be several months before the overall risk of exposure is low because so many others have been immunized. Until most of the population is vaccinated, wearing masks, social distancing and handwashing are the only tools we have to stop the spread of COVID-19.

This blog was reviewed by Jonathan Pinsky, MD, infectious disease physician and medical director of infection control and prevention at Edward Hospital.

For the latest updates on the COVID-19 vaccine, please check EEHealth.org/coronavirus/vaccine.

Are you wondering whether to get the vaccine? Read our blog to learn more.

If you feel ill, Edward-Elmhurst Health offers screening options for COVID-19. Eleanor, your personal virtual assistant, can help you check your symptoms 24/7 and advise you on what to do next. We also offer Video Visits and E-Visits for COVID-19 symptoms.

The information in this article may change at any time due to the changing landscape of this pandemic. Read the latest on COVID-19.