COVID-19 Vaccines

The COVID-19 pandemic is a public health emergency. Manufacturers have responded to this urgent need by developing vaccines for the new coronavirus as quickly and safely as possible.

In the United States, the Food and Drug Administration (FDA) is responsible for protecting the public health in partnership with the United States government and others. The FDA can grant an emergency use authorization (EUA) to a manufacturer if it provides enough evidence that a vaccine is safe and effective.

The government (via the FDA) has selected vaccines that are promising. It has also helped fund large-scale production of these vaccines while safety data were being collected. This was done so that distribution of vaccines could begin quickly after they receive emergency approval.

The approval of a vaccine is not affected by having the clinical trial and the manufacturing process take place at the same time. If a vaccine does not meet standards, then it will not be used.

The COVID-19 vaccines are being held to the same standards used to assess the safety and effectiveness of other vaccines currently available in the United States. The only COVID-19 vaccines the FDA will approve for use are those that meet these standards. 

The approval process has many layers. In addition to a careful review by the FDA, independent scientific and public health experts study the safety and efficacy data to offer input on whether the vaccines should be approved.

Even after vaccines are distributed, monitoring for safety will continue. 

It is quite likely that your doctors and other clinicians you trust every day already have received these vaccines.

The FDA has authorized three COVID-19 vaccines for use in the United States:

• Pfizer-BioNTech
• Moderna
• Johnson & Johnson/Janssen

The FDA has fully approved the Pfizer-BioNTech vaccine to prevent COVID-19 for people who are 16 and older. The Pfizer vaccine also is authorized for emergency use in adolescents who are 12-15 years old.

Emergency use may be granted if there is strong enough evidence that the vaccines are safe and effective.

The FDA has authorized the Moderna and Johnson & Johnson/Janssen vaccines for emergency use in adults who are 18 and older.

These vaccines are safe, effective, and lower your risk of severe illness. 

The CDC recommends getting the first COVID-19 vaccine available to you.

Two COVID-19 vaccines available in the United States – Pfizer-BioNTech and Moderna – are messenger RNA, also known as mRNA, vaccines. Researchers have been studying mRNA vaccines for decades.

Unlike other vaccines, mRNA does not use an inactive form of the virus to cause your body to react and learn to defend itself. Instead, mRNA delivers instructions to your body to tell it how to protect itself against the virus.

There is a very rare chance of having blood clots with low platelets after receiving a COVID-19 vaccine. In the rare event that this type of blood clot occurs, hospitals and doctors have the tools to diagnose and treat this condition.

This condition has been seen only with the COVID-19 vaccines from Johnson & Johnson and AstraZeneca. The AstraZeneca vaccine is not available in the United States. The condition has not been reported in patients who received the Moderna or Pfizer vaccines. 

Out of nearly 7 million doses of the Johnson & Johnson COVID-19 vaccine given, there were 15 reported cases of blood clots with low platelets, the CDC confirmed on April 23.  All those cases occurred in women who were 18-59 years old. 

“Women younger than 50 years old especially should be aware of the rare risk of blood clots with low platelets after vaccination, and that other COVID-19 vaccines are available where this risk has not been seen,” the CDC states. 

It’s important to know that the risk of severe illness from COVID-19 outweighs the low risk of developing a blood clot after a COVID-19 vaccine. 

The authorized COVID-19 vaccines are safe and effective at preventing severe COVID-19 infection. The CDC recommends getting the first COVID-19 vaccine available to you. 

The window of risk for developing blood clots linked to COVID19 vaccination appears to be narrow – between 5 and 28 days after vaccination. 

For three weeks after receiving the vaccine, the CDC recommends watching for possible signs of a blood clot with low platelets. These include:

• Severe headaches or blurred vision
• Shortness of breath
• Chest pain
• Leg swelling
• Abdominal pain
• Bruising easily

If you experience these symptoms, call your doctor. 

The Pfizer and Moderna vaccines require two shots in total. The second shot should be given three or four weeks after the first one. The Johnson & Johnson vaccine requires only one shot.

Importantly, you cannot get COVID-19 from being vaccinated.

The vaccine you will be given depends on the supply at the time you are vaccinated. You most likely will not get to choose which vaccine you will get. All the authorized COVID-19 vaccines will be effective in protecting you against COVID.

COVID-19 vaccines are now available to everyone who is 12 or older. 

To learn more about recommendations for different groups of people, visit the CDC website: COVID-19 Vaccine Information for Specific Groups.

People at increased risk of severe illness from COVID-19 include people with existing:

• Heart conditions 
• Lung disease (chronic obstructive pulmonary disease or COPD)
• High blood pressure
• Diabetes 
• Obesity 
• Cancer
• Illnesses that lower the immune system’s ability to fight infection (for example, people undergoing cancer treatments or organ transplants) 

However, experts are still learning about COVID-19. Other medical conditions might also increase your risk, for example moderate-to-severe asthma or being overweight. 

For the full list of health conditions, visit the CDC website: People With Certain Medical Conditions. 

According to the CDC, severe illness from COVID-19 means that you experience any of the following:

• Are admitted to the hospital
• Need care in the intensive care unit
• Require help or a mechanical device to breathe

Severe illness can also lead to death.

People who are pregnant have a higher chance of severe illness from COVID-19.

If you are pregnant or breastfeeding, the CDC recommends you get vaccinated against COVID-19. The data we have so far about COVID-19 vaccines given during pregnancy suggest the benefits of the vaccines outweigh the potential risks.

If you are pregnant, talk to your care team about your concerns and for help to make the right choice for you.

People who are fully vaccinated may need an additional dose, or booster shot, to strengthen their body’s protection against COVID-19.

The U.S. Department of Health and Human Services announced a plan to offer booster shots starting the week of Sept. 20 to people who received an mRNA vaccine (Pfizer or Moderna). You will be able to get a third dose when it has been eight months since you were fully vaccinated. Health care workers, nursing home residents and other people older than 65 will be the first ones to receive booster shots.

People who received the Johnson and Johnson vaccine likely will also need a booster shot. More details will follow in the coming weeks.

The CDC recommends an additional dose of the mRNA vaccine for people who have Illnesses that lower the immune system’s ability to fight infection, for example people undergoing cancer treatments, or bone marrow or organ transplants. For the full list of conditions, visit the CDC website: COVID-19 Vaccines for Moderately to Severely Immunocompromised People.

The CDC recommends an additional dose of the mRNA vaccine for people who have Illnesses that lower the immune system’s ability to fight infection, for example people undergoing cancer treatments, or bone marrow or organ transplants.

For the full list of conditions, visit the CDC website: COVID-19 Vaccines for Moderately to Severely Immunocompromised People.

If you have a weakened immune system and received one of the mRNA vaccines, you should get a third dose of vaccine at least four weeks after a second dose of the Pfizer or Moderna vaccines.

Check with your care provider or nearby drugstore. Visit your local health department’s website to learn your state’s plan. 

You can also visit Vaccines.gov (www.vaccines.gov) to find where to get the COVID-19 vaccine near you. 

The U.S. government is working to ensure that the vaccines will be distributed in a convenient way and at no cost.

There may be some side effects that are mostly mild. Participants in the vaccine clinical trials reported having a fever or aches lasting a day or two after getting a shot. Other side effects may be arm soreness or headache.

Although rare, a few people have had a severe allergic reaction after getting the vaccine. When you get your shot, you will be asked to stay on site for at least 15 minutes. If you have a bad reaction, care providers can give you medicine to treat it. There are safeguards in place to monitor and take care of you.

Overall, the vaccines were found to be safe.

You should continue to wear a mask and keep a safe distance from others not in your household until your vaccine has taken effect.

You are considered “fully vaccinated” two weeks after your second dose of a two-dose vaccine (Pfizer or Moderna), or two weeks after your one-dose vaccine (Johnson & Johnson). 

After you are fully vaccinated, you can start to do some things that you did before the pandemic. Check with your local government for the rules in your area.

To help prevent the spread of COVID-19 and for added protection, the CDC recommends wearing a mask indoors in public spaces if you are in an area with high numbers of COVID-19 cases. You can find this information for your community at the CDC website.

For more details and the latest guidance, visit When You’ve Been Fully Vaccinated. 

It’s not clear how long the vaccine will protect you. More research is being conducted to understand this over a longer time.