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What You Should Know About COVID-19 Vaccines and Diabetes

By Eliza Skoler and Dr. Francine Kaufman

COVID-19 vaccines are being distributed in the United States and in many parts of the world. We’re here to answer questions for people with diabetes. Are the vaccines safe? How do the vaccines work and does it matter which one I get? What are the side effects, and how will the vaccine affect my blood sugar? What can I do after I am vaccinated?

Now that three COVID-19 vaccines have been authorized for use in the United States, and ten more around the world, many questions are circulating about the vaccines, their safety, and when to get vaccinated. People with diabetes (type 1 or type 2) or obesity are now prioritized for vaccination across the US, and people over the age of 16 are eligible for vaccination in most states. We’re here to answer your questions about COVID vaccination in the US; we’ll update this article as more information becomes available. 

Click to jump down to a group of questions:

Why get the vaccine?
Why should I get the COVID vaccine?
How does the COVID-19 vaccine work?
How do mRNA vaccines work?​
How do viral vector vaccines work?

Vaccine Safety
Is the vaccine safe for people with diabetes?
Does it matter which vaccine you get?
Which vaccine is best for people with diabetes?​
What are the side effects? Can the vaccine be dangerous?
How will the vaccine affect my blood sugar levels?
Do diabetes medications affect the vaccine?
Should I get vaccinated if I have diabetes and other health conditions?
What is the AstraZeneca vaccine?

Getting the Vaccine
When will people with diabetes get the vaccine?
How will I know when it’s my turn to get the vaccine?
How much does the vaccine cost?
What should I expect at my vaccine appointment?
I had COVID-19 – should I still get vaccinated?
If I have symptoms of COVID-19 now should I get the vaccine?

After Receiving the Vaccine
What happens after I get the vaccine – can I still infect people with COVID?
Can I see people now that I am vaccinated?
Is one dose of the COVID vaccine effective?
Does the vaccine protect against the new variant of COVID?
Can I get COVID from the vaccine?
Are other vaccines coming?
When can I stop wearing a mask?

Why get the vaccine?

Why should I get the COVID vaccine?

The vaccine has the ability to protect you, your loved ones, and your community. It will help your body’s immune system fight off a COVID-19 infection – this means that if you are exposed to COVID, your body can protect you and significantly reduce your chances of getting sick or experiencing severe complications from the virus. Two of the vaccines that are currently authorized in the US (from Pfizer-BioNTech and Moderna) are almost 95% effective at preventing symptoms of COVID in adults who have been exposed, and the third vaccine (Johnson & Johnson) is 85% effective at preventing severe COVID infection. In other words, if you are vaccinated with any of the three and then come into contact with someone who has COVID, you probably won’t get sick.

To stop the global spread of COVID-19, the majority of people around the world will have to become immune to the virus. The COVID vaccine – like the many vaccines that protect us from small pox, measles, the flu, and other illnesses – will play a major role in improving the health and wellbeing of people across the globe.

How does the COVID-19 vaccine work?

There are currently three vaccines that have received emergency use authorization in the US: the Pfizer-BioNTech, Moderna, and Johnson & Johnson vaccines. The Pfizer-BioNTech and Moderna vaccines are similar – both use messenger RNA (mRNA) to target the “spike proteins” on COVID-19 virus molecules. The Johnson & Johnson vaccine is a viral vector vaccine that also targets the spike proteins.

How do COVID mRNA vaccines work?

mRNA contains genetic instructions (like a blueprint) for making specific proteins in cells. The mRNA in COVID vaccines was developed by scientists to trigger human cells to make harmless COVID spike proteins, and after the proteins are built the vaccine mRNA is destroyed. The body’s immune system then recognizes these foreign proteins and builds antibodies against them. This means that if you are later infected with COVID-19, you’ll have antibodies that recognize the spikes on the viral molecule and can destroy it. To learn more about this process view this detailed, interactive piece from the New York Times.

mRNA vaccines are not “live” vaccines – the live virus is not injected into a person’s body. This means that you cannot get COVID from the vaccine. Similarly, the vaccine will not alter your own genes.

How do COVID viral vector vaccines work?

Similar to an mRNA vaccine, a viral vector vaccine causes the body’s cells to make harmless COVID-19 spike proteins so that it can learn to recognize the foreign proteins and build antibodies against them. Later, if you are infected with COVID-19, your body will have antibodies ready to fight off the virus.

Instead of using mRNA, a viral vector vaccine contains the DNA for a different, harmless virus. In the case of the Johnson & Johnson vaccine, it’s an adenovirus – the type of virus that normally causes a cold or a flu – that has been engineered so that it does not make you sick. Once you get the injection and the virus is inside your body, its DNA can be read by your cellular machinery to produce spike proteins. As your immune system works to fight these foreign proteins, it will learn to protect you from COVID-19. To learn more about this process view a detailed, interactive piece from the New York Times.

Vaccine Safety

Is the vaccine safe for people with diabetes?

All three currently authorized vaccines – Pfizer-BioNTech, Moderna, and Johnson & Johnson – appear to be safe and effective for adults with diabetes. Rigorous clinical trials tested the safety of these vaccines in adults of all ages, races, and ethnicities, as well as chronic health conditions.

  • The Pfizer-BioNtech trial included 3,150 people with diabetes (8.4% of trial participants).

  • The Moderna trial included 2,858 people with type 1, type 2, and gestational diabetes (9.4% of trial participants).

  • The Johnson & Johnson trial included 3,389 people with type 1 and type 2 diabetes (7.7% of trial participants).

  • In terms of racial and ethnic diversity, the trials each included more than 20% Hispanic or Latino participants, almost 10% African American participants, and almost 5% Asian participants.

These vaccines were advanced quickly thanks to the immense resources provided for COVID vaccine development – even with a speedy process, the vaccine manufacturers had to follow the typical safety steps and thorough checks. Read more from the CDC about how the vaccines work, potential side effects, and details from the human clinical trials.

Does it matter which vaccine you get?

No – all three of the vaccines will protect you and those around you. However, there are some differences between the vaccines that may be important to people with diabetes.

Clinical trials found both mRNA vaccines to be extremely effective in adults – with almost 95% efficacy overall, only one in 20 people that receives the vaccine would get sick from COVID. Among the trial participants with diabetes, the Pfizer-BioNtech was 95% effective and the Moderna vaccine was 100% effective, while the Johnson & Johnson vaccine was 53% effective. Participants were only followed for a few months, so we don’t yet know the long-term effectiveness of these vaccines. As more vaccines are administered there will be more data collected, and hopefully children will be enrolled in clinical trials soon.

What does it mean for these vaccines to be “effective?” If a vaccine is 50% effective it successfully protects half of the people who receive it from getting infected by COVID-19 if they are exposed. If a vaccine is 75% effective, it protects three out of four people from COVID-19 infection. More importantly, all three vaccines are highly effective at preventing severe COVID-19 infection. All three clinical trials found that in people who did get infected after vaccination, the infection was much milder – among people who had received one of the three authorized vaccines, there were almost no deaths or hospitalizations resulting from COVID-19. To learn more about how the three vaccines compare, watch this video.

During early vaccine distribution, you likely won’t have any choice in which vaccine is available to you because there will be a limited supply and the goal is to vaccinate people as quickly as possible. Both mRNA vaccines require two shots, meaning that they are not considered fully effective until you have received both doses, and your immune system has developed protection against the virus (after the second shot). You should receive two shots of the same vaccine (either Pfizer-BioNtech or Moderna). The Johnson & Johnson vaccine only requires one shot.

Which vaccine is best for people with diabetes?

Due to the distinct design of each clinical trial, it can be hard to directly compare the three vaccines that are currently authorized in the US. However, based on trial data and information from the vaccine manufacturers, here’s the best information we have on how the vaccines compare.

 

Pfizer-BioNTech

Moderna

Johnson & Johnson

How effective is it?

95% effective at preventing COVID with symptoms 

94% effective at preventing COVID with symptoms 

66% effective at preventing COVID with symptoms; 85% effective against severe COVID-19 illness

Vaccine type

mRNA

mRNA

Viral vector

How many doses?

2 (about 21 days apart)

2 (about 28 days apart)

1

How long until you’re protected?

2 weeks after the second shot (~ 5 weeks total)

2 weeks after the second shot (~ 6 weeks total)

2 weeks after the shot

The data show that no matter which of the currently authorized vaccines you get, getting a COVID-19 vaccine is safe and important for people with diabetes. All three vaccines are highly protective against severe COVID illness and death. Click here to watch an in-depth video explaining how the vaccines compare.

What are the side effects? Can the vaccine be dangerous?

When you receive a vaccine for a particular virus, your immune system builds protection against it. Because your body is creating antibodies and learning how to fight the virus or bacteria targeted by the vaccine, you may experience normal side effects for a day or two – this is similar to getting a flu shot, and people with diabetes should monitor their blood sugar levels and have a sick day management plan ready.

According to the CDC, these are the common side effects of the COVID vaccines – they are similar for people with and without diabetes:

  • Pain, swelling, or redness in the vaccinated arm

  • Fever

  • Chills

  • Fatigue

  • Headache

  • Nausea

  • Muscle pain

These side effects are a result of your immune system preparing to combat a future viral infection – they do not mean that you have gotten sick from the vaccine itself. If your side effects don’t go away, contact your healthcare team.

Severe allergic reactions to the COVID vaccine are rare – you can learn more from the CDC here. If you have ever had an allergic reaction to any vaccine, ask your healthcare professional if you should get the COVID vaccine. If you experience a severe allergic reaction to the first dose of the COVID vaccine, do not get the second dose.

How will the vaccine affect my blood sugar levels?

Because the vaccine can cause symptoms of illness that can lead to high glucose levels, it’s important to carefully monitor your blood sugar levels for 48 hours after you receive your vaccination. Stay hydrated, and make sure to have your sick day plan ready in case you feel ill. So far, people with diabetes seem to be experiencing few side effects and minimal effect on blood sugar levels.

Do diabetes medications affect the vaccine?

At this time there is no information available on drug interactions between the authorized COVID vaccines and other medications – this has not yet been studied. However, it is not anticipated that the vaccine itself would interact with insulin or other standard diabetes medications. Note: it may be helpful to avoid injecting insulin or placing a glucose sensor or pump infusion set in your vaccine injection site for several days after vaccination.

Should I get vaccinated if I have diabetes and other health conditions?

People with complications of diabetes (including heart disease and kidney disease) are at much higher risk of severe illness from COVID-19. If you have other health conditions in addition to diabetes, getting the vaccine is especially important.

What is the AstraZeneca vaccine?

The primary results from the US clinical trial of the AstraZeneca viral vector vaccine show that the vaccine was 76% effective at preventing symptoms of COVID-19 infection, and fully prevented severe illness and hospitalization in more than 32,000 participants. The two-dose AstraZeneca vaccine is currently authorized in Europe and in other countries, but has not yet been authorized for use in the US. The latest clinical trial results show the vaccine to be both safe and effective.

In early March, several countries briefly paused giving people the AstraZeneca COVID vaccine due to concerns about possible rare side effects, including severe blood clots. Among the 34 million people who have received at least one dose of the vaccine in Europe, there have been at least 222 suspected cases, and more than 30 deaths, caused by these rare side effects. Though it’s unknown whether the vaccine is directly causing these worrisome reactions, the European Medicines Agency has acknowledged a likely association. As a result, many countries, including France, Germany, and the UK, are restricting the vaccine’s use among younger people. Young people have a much lower risk of becoming severely ill or dying as a result of COVID-19, so the benefits of the AstraZeneca vaccine may not outweigh the risk of rare side effects.

However, the EMA and researchers still stress that the vaccine is highly beneficial in the majority of circumstances, even for younger populations. We look forward to updating this article as more information on these side effects comes to light and if the AstraZeneca vaccine receives FDA authorization in the US.

Getting the Vaccine

When will people with diabetes get the vaccine?

People with "high-risk" medical conditions, which include diabetes or obesity, are now eligible for vaccination in every state in the US. Previously, only type 2 diabetes and obesity were recommended for prioritization during this phase of vaccination; however, the CDC recently classified type 1 diabetes as a high-risk medical condition. We urge you to get vaccinated as soon as you are eligible. To learn about the CDC’s recommended stages of vaccination and where you fall in the vaccine line, read Dr. Francine Kaufman’s “When Can I Get the COVID Vaccine if I Have Diabetes?

How will I know when it’s my turn to get the vaccine?

If you have type 1 diabetes, type 2 diabetes, or obesity (a body mass index above 30 – check here), please get vaccinated as soon as you are eligible where you live. Contact your healthcare office to ask when and how you can get vaccinated. You can also visit vaccinefinder.org to find available appointments in your area.

The distribution of vaccines is the responsibility of each state, and states have different plans for vaccinating people. Most states are using networks within hospitals, healthcare offices, and pharmacies to distribute vaccines to residents. Click here to see the state by state report from the Kaiser Family Foundation, including who is currently eligible for vaccination in your state.

How much does the vaccine cost?

You will not have to pay for the COVID vaccine in the US; it will be given to all US residents for free. That said, some vaccination providers may charge an administration fee for delivering the injection. Ask your healthcare office if there will be any costs associated with your vaccination.

What should I expect at my vaccine appointment?

When you get your COVID vaccine, you’ll receive a paper card that says which vaccine you received, and when and where you received it. You’ll also get a fact sheet (paper or electronic) with more information about the vaccine, its benefits, and its side effects. After you get your injection, you’ll be asked to stay on-site for a short period of time so that healthcare professionals can monitor your body’s reaction.

I had COVID-19 – should I still get vaccinated?

Yes. Researchers don’t know how long immunity against the virus can last after natural infection, so you should get vaccinated for long-term protection. If you were treated for COVID-19 with monoclonal antibodies or convalescent plasma, the CDC says that you should wait 90 days after the infection before getting your vaccine.

If I have symptoms of COVID-19 now, should I get the vaccine?

If you recently tested positive for COVID-19, are currently experiencing symptoms, or were exposed to someone with COVID, please stay away from other people.

  • If you test positive for COVID, wait until you've recovered (as early as 14 days from infection).

  • If you are experiencing symptoms of COVID, self-isolate and get tested. 

  • If you were exposed to someone with COVID, quarantine for 14 days and monitor yourself for symptoms. Get a COVID test. If you do not get sick and your test is negative, get vaccinated once your quarantine period is over.

After Receiving the Vaccine

What happens after I get the vaccine – can I still infect people with COVID?

Once you have received both doses of the vaccine, it should protect you from getting sick with COVID. However, researchers don’t know whether you may be able to carry the virus (without symptoms) and pass it on to others. That’s why it’s still important to maintain safety measures even after receiving the vaccine: wear a face mask that fits you well if you're in public, avoid contact with people not in your household, social distance from others, wash your hands, and monitor your health. Continuing to follow these measures will help you protect others and your community.

Can I see people now that I am vaccinated?

Two weeks after your final vaccine dose (one dose for Johnson & Johnson, two doses for Pfizer-BioNTech or Moderna) you are considered to be fully vaccinated and protected against severe COVID-19 infection. According to new CDC guidelines, people who are fully vaccinated:

  • Can gather indoors with others who are fully vaccinated, with no need to wear a mask.

  • Do not need to quarantine, stay away from others, or get tested if exposed to someone with COVID – unless you begin to show symptoms of illness.

The CDC also says that people who are fully vaccinated can “visit with unvaccinated people from a single household who are at low risk for severe COVID-19 disease indoors without wearing masks or physical distancing.” However, people with diabetes have a higher risk of getting severely ill from COVID-19 (though there's no greater chance of being infected). For this reason, even if you are vaccinated, please continue to be cautious.    

Is one dose of the COVID vaccine effective?

For the Johnson and Johnson vaccine, yes.

For the Pfizer-BioNTech and Moderna vaccines, not entirely. Results from the clinical trials (Pfizer-BioNTechModerna) show that one dose of the vaccine can offer some protection, but two doses of both authorized vaccines are required for full efficacy.

Does the vaccine protect against the new variant of COVID?

Probably, but not certainly. Researchers are still studying the newest variants of COVID-19 to determine how effective current vaccines are at protecting against them. So far, much of the virus structure is unchanged in the variants and the currently-authorized vaccines seem to produce antibodies that recognize variants of COVID-19. Other strains of COVID will likely develop with time (similarly to the flu), and the vaccines can then be tweaked to match the changed threat. Click here to learn more about COVID variants, how they work, and what you can do to protect yourself.

Can I get COVID from the vaccine?

No. The vaccines do not contain the live virus, so they cannot infect you with COVID-19. Side effects that appear after you receive the vaccine occur because your immune system is activating and building antibodies – they are not signs of infection.

After vaccination it takes time for your body to develop full immunity to the virus, so it is still possible to get infected with COVID in the days before or after your vaccination. This does not mean the vaccine did not work; rather, it means that your immune system did not have enough time to build full immunity from the vaccine before coming into contact with the virus.

Are other vaccines coming?

To date, 13 vaccines have been approved for full or limited use around the world. Seventy-eight vaccines are currently in different stages of human clinical trials: 55 are in the early stages and 23 are in the final stages of testing. Hopefully, some of these vaccines will be found to effectively protect against COVID, opening up more vaccination options for people around the world. To track global vaccine development, view the New York Times Coronavirus Vaccine Tracker.

When can I stop wearing a mask?

Even after you get the vaccine you should still wear a face mask whenever you are in public places. Masks will continue helping to shield you from the virus and new variants of COVID (since no vaccine is perfect), and will reduce your chances of spreading COVID-19 to people around you (if you are carrying the virus and don't have symptoms). As more people get vaccinated, the number of people carrying the virus in your community will decrease, bringing the risk of infection down. Public health authorities will make announcements about this, which may vary from place to place and even with the season. 

If you are fully vaccinated, you can begin spending time with others who are fully vaccinated without wearing face masks.  

While we await further information and research on COVID vaccines, protect yourself and those around you. For more information, read “Staying Safe – And Staying Well – During a Pandemic Winter” and "COVID Variants, Double Masks, Diabetes, Oh My!"

Editor’s note: This article was first published on January 8, 2021, and last updated on April 12.

Dr. Francine Kaufman is Chief Medical Officer at Senseonics, a diabetes device company and Distinguished Professor Emerita of Pediatrics and Communications at the Keck School of Medicine, University of Southern California.

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