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gloved hands with a vile and needle
gloved hands with a vile and needle
gloved hands with a vile and needle

COVID-19 Vaccine: What You Need to Know

Featured Experts:

Researchers and drug manufacturers are developing and testing vaccines for the coronavirus that causes COVID-19. Lisa Maragakis, M.D., M.P.H., senior director of infection prevention, and Gabor Kelen, M.D., director of Johns Hopkins Office of Critical Event Preparedness and Response, address common questions and explain how a vaccine could affect the current pandemic.

How do vaccines work?

Vaccines help people develop immunity to a virus or other germ. A vaccine introduces a less harmful part of that germ — or something created to look or behave like it — into a person’s body. The body’s immune system develops antibodies that fight that particular germ and keep the person from getting sick from it. Later, if the person encounters that germ again, their immune system can “recognize” it and “remember” how to fight it off.

Is there a vaccine for the coronavirus disease?

No, there is not yet a vaccine for the SARS-CoV-2 coronavirus that causes COVID-19, but several are in development and being tested.

How will a vaccine prevent COVID-19?

The coronavirus that causes COVID-19 has spikes of protein on each virus. These spikes help the viruses attach to cells and cause disease. Some of the coronavirus vaccines in development are designed to block the function of these protein spikes; others prevent them from forming.

An effective vaccine will protect a person who receives it by lowering their chances of getting COVID-19 if they encounter the coronavirus. Widespread vaccination for the coronavirus means that the virus will not infect as many people. This will limit spread through communities.

Safety and Effectiveness of a COVID-19 Vaccine

How will we know if a COVID-19 vaccine is safe and effective?

In order to be declared safe and effective, a COVID-19 vaccine must pass certain tests and standards. Organizations such as the National Academy of Sciences, the National Institutes for Health, and the Food and Drug Administration (FDA) use scientific data from research to help decide if and when new drugs and vaccines can become available to the public. It is important to note that you cannot get COVID-19 from a vaccine. The vaccine would contain proteins or other biological substances to stimulate the immune response, but not the coronavirus itself.

How long will it protect me? Will I have to get a COVID-19 shot every year?

A few people who have had COVID-19 have apparently had a second, often milder case of the disease, and researchers are exploring what this means in terms of how long immunity from the coronavirus lasts. Vaccine developers are looking at ways to boost the effectiveness of a vaccine so that it provides longer immune protection than a natural infection with the coronavirus.

Will the vaccine work if I’ve already had COVID-19 or tested positive for the coronavirus?

It is not yet clear how long a person who has had COVID-19 is immune to the coronavirus. If the immunity is not long lasting, a vaccination may be recommended to protect you from getting COVID-19 again.

If I get a coronavirus vaccination, do I still have to wear a mask? Physical distance?

Yes. It may take time for everyone who wants a COVID-19 vaccination to get one. Also, while the vaccine may prevent you from getting sick, it is unknown at this time if you can still carry and transmit the virus to others. That is why, until more is understood about how well the vaccine works, continuing with precautions such as mask-wearing and physical distancing will be important.

Availability of a COVID-19 Vaccine

When will the COVID-19 vaccine be available?

The vaccine will be available once it has been carefully tested and approved by regulating organizations such as the FDA, and manufactured and distributed throughout the country.

But because COVID-19 is a widespread illness and can be serious, an emergency use authorization may be granted by the FDA if there is strong enough scientific evidence that a vaccine is both effective and safe to give to millions of people, making it available as soon as reasonably possible. Once a vaccine is approved, scientists and doctors will monitor its use and, if necessary, adjust any approved vaccine to improve it if necessary.

Will there be enough vaccine for everyone who wants it?

After approval of the first vaccine, there will be a limited supply at first. Manufacturing adequate supplies of a vaccine will take time, and distribution among the general public could be challenging if the vaccine requires special handling, such as temperature control, in order to ensure it works properly.

Who is likely to get a COVID-19 vaccination first?

If limited amounts of a COVID-19 vaccine are available, the vaccine might be made available to groups of people based on priority. For instance, vulnerable people such as those undergoing cancer treatment, and hospital workers and first responders might receive the COVID-19 vaccine before others, who are less at risk.

Will it be easier or harder to get in some areas?

There could be differences in availability from one place to another. Availability might depend on how much vaccine is produced and how it needs to be transported and stored. For instance, some vaccines must be kept frozen at very low temperatures in order to be effective. Every effort will be made to distribute the vaccine equitably.

Will children and older adults be included?

Older adults will be eligible to receive a vaccine once approved, again, depending on vaccine supplies and their health status. Once an effective vaccine is found, manufactured and distributed, everyone who wants a COVID-19 vaccination should, eventually, be able to get one. But vaccination programs may roll out in stages, depending on priority. People over 65 might be vaccinated earlier, since they are more vulnerable to severe COVID-19 disease and death.

At this time, vaccine trials including children have not been completed. Vaccines can affect children differently than adults, so further testing will be necessary to make sure any coronavirus vaccine is safe for children. Although severe cases of COVID-19 in children have occurred, many otherwise healthy children who become infected with the coronavirus experience mild cases of COVID-19, or no symptoms at all. For these reasons, children are not likely to be first in line as the vaccination programs begin.

Scientist carefully insets a pipette into a test tube.

Coronavirus (COVID-19)

What you need to know from Johns Hopkins Medicine.

Published November 18, 2020.