What you need to know about COVID-19 vaccines
Answers to the most common questions about coronavirus vaccines. (last updated on 25 October 2022)
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Vaccines save millions of lives each year. The development of safe and effective COVID-19 vaccines is a crucial step in helping us get back to doing more of the things we enjoy with the people we love.
We’ve gathered the latest expert information to answer some of the most common questions about COVID-19 vaccines. Keep checking back as we will update this article as more information becomes available.
How do COVID-19 vaccines work?
Vaccines work by mimicking an infectious agent – viruses, bacteria or other microorganisms that can cause a disease. This ‘teaches’ our immune system to rapidly and effectively respond against it.
Traditionally, vaccines have done this by introducing a weakened form of an infectious agent that allows our immune system to build a memory of it. This way, our immune system can quickly recognize and fight it before it makes us ill. That’s how some of the COVID-19 vaccines have been designed.
Other COVID-19 vaccines have been developed using new approaches, which are called messenger RNA, or mRNA, vaccines. Instead of introducing antigens (a substance that causes your immune system to produce antibodies), mRNA vaccines give our body the genetic code it needs to allow our immune system to produce the antigen itself. mRNA vaccine technology has been studied for several decades. They contain no live virus and do not interfere with human DNA.
Read more on the differences among COVID-19 vaccines.
For more information on how vaccines work, please visit WHO.
Are COVID-19 vaccines safe?
Yes, COVID-19 vaccines have been safely used to vaccinate billions of people. The COVID-19 vaccines were developed as rapidly as possible, but they had to go through rigorous testing in clinical trials to prove that they meet internationally agreed benchmarks for safety and effectiveness. Only if they meet these standards can a vaccine receive validation from WHO and national regulatory agencies.
UNICEF only procures and supplies COVID-19 vaccines that meet WHO’s established safety and efficacy criteria and that have received the required regulatory approval.
How were COVID-19 vaccines developed so quickly?
Scientists were able to develop safe effective vaccines in a relatively short amount of time due to a combination of factors that allowed them to scale up research and production without compromising safety:
- Because of the global pandemic, there was a larger sample size to study and tens of thousands of volunteers stepped forward
- Advancements in technology (like mRNA vaccines) that were years in the making
- Governments and other bodies came together to remove the obstacle of funding research and development
- Manufacturing of the vaccines occurred in parallel to the clinical trials to speed up production
- Though they were developed quickly, all COVID-19 vaccines approved for use by the WHO are safe and effective.
Which COVID-19 vaccine is best for me?
All WHO-approved vaccines have been shown to be highly effective at protecting you against severe illness and death from COVID-19. The best vaccine to get is the one most readily available to you.
You can find a list of those approved vaccines on WHO’s site.
Remember, if your vaccination involves two doses, it’s important to receive both to have the maximum protection.
Do the COVID-19 vaccines protect against variants?
The WHO-approved COVID-19 vaccines continue to be highly effective at preventing severe illness and death.
However, the vaccines offer less protection against infection from Omicron, which is the dominant variant globally. That's why it's important to get vaccinated and continue measures to reduce the spread of the virus – which helps to reduce the chances for the virus to mutate – including physical distancing, good ventilation, regular handwashing and seeking care early if you have symptoms.
Who should be vaccinated first?
Each country must identify priority populations, which WHO recommends are frontline health workers (to protect health systems) and those at highest risk of death due to COVID-19, such as older adults and people with certain medical conditions.
Other essential workers, such as teachers and social workers, should then be prioritized, followed by additional groups as more vaccine doses become available.
The risk of severe illness from COVID-19 is very low amongst healthy children and adolescents, so unless they are part of a group at higher risk of severe COVID-19, it is less urgent to vaccinate them than these priority groups.
Children and adolescents who are at higher risk of developing severe illness from COVID-19, such as those with underlying illnesses, should be prioritized for COVID-19 vaccines.
When shouldn’t you be vaccinated against COVID-19?
If you have any questions about whether you should receive a COVID-19 vaccine, speak to your healthcare provider. At present, people with the following health conditions should not receive a COVID-19 vaccine to avoid any possible adverse effects:
- If you have a history of severe allergic reactions to any ingredients of a COVID-19 vaccine.
- If you are currently sick or experiencing symptoms of COVID-19 (although you can get vaccinated once you have recovered and your doctor has approved).
Should I get vaccinated if I already had COVID-19?
Yes, you should get vaccinated even if you’ve previously had COVID-19. While people who recover from COVID-19 may develop natural immunity to the virus, it is still not certain how long that immunity lasts or how well it protects you against COVID-19 reinfection. Vaccines offer more reliable protection, especially against severe illness and death.
I’m breastfeeding. Should I get vaccinated against COVID-19?
Yes, if you are breastfeeding you should take the vaccine as soon as it is available to you. It is very safe and there is no risk to the mother or baby. None of the current COVID-19 vaccines have live virus in them, so there is no risk of you transmitting COVID-19 to your baby through your breastmilk from the vaccine. In fact, the antibodies that you have after vaccination may go through the breast milk and help protect your baby.
I’m pregnant. Can I get vaccinated against COVID-19?
Yes, you can get vaccinated if you are pregnant. COVID-19 during pregnancy puts you at higher risk of becoming severely ill and of giving birth prematurely.
Many people around the world have been vaccinated against COVID-19 while pregnant or breastfeeding. No safety concerns have been identified for them or their babies. Getting vaccinated while pregnant helps to protect your baby. For more information about receiving a COVID-19 vaccination while pregnant, speak to your healthcare provider.
Can COVID-19 vaccines affect fertility?
No, you may have seen false claims on social media, but there is no evidence that any vaccine, including COVID-19 vaccines, can affect fertility in women or men. You should get vaccinated if you are currently trying to become pregnant.
Should my child or teen get a COVID-19 vaccine?
An increasing number of vaccines have been approved for use in children. They’ve been made available after examining the data on the safety and efficacy of these vaccines, and millions of children have been safely vaccinated around the world. Some COVID-19 vaccines have been approved for children from the age of 6 months old. Check with your local health authorities on what vaccines are authorized and available for children and adolescents where you live.
Children and adolescents tend to have milder disease compared to adults, so unless they are part of a group at higher risk of severe COVID-19, it is less urgent to vaccinate them than older people, those with chronic health conditions and health workers.
Remind your children of the importance of us all taking precautions to protect each other, such as avoiding crowded spaces, physical distancing, and hand washing.
It is critical that children continue to receive the recommended childhood vaccines.
Can COVID-19 vaccines affect your DNA?
No, none of the COVID-19 vaccines affect or interact with your DNA in any way. Messenger RNA, or mRNA, vaccines teach the cells how to make a protein that triggers an immune response inside the body. This response produces antibodies which keep you protected against the virus. mRNA is different from DNA and only stays inside the cell for about 72 hours before degrading. However, it never enters the nucleus of the cell, where DNA is kept.
What is COVAX?
COVAX is a global effort committed to the development, production and equitable distribution of vaccines around the world. No country will be safe from COVID-19 until all countries are protected.
There are 190 countries and territories engaged in the COVAX Facility, which account for over 90 per cent of the world’s population. Working with CEPI, GAVI, WHO and other partners, UNICEF is leading efforts to procure and supply COVID-19 vaccines on behalf of COVAX.
Learn more about COVAX.
I’ve seen inaccurate information online about COVID-19 vaccines. What should I do?
Sadly, there is a lot of inaccurate information online about the COVID-19 virus and vaccines. A lot of what we’re experiencing is new to all of us, so there may be some occasions where information is shared, in a non-malicious way, that turns out to be inaccurate.
Misinformation in a health crisis can spread paranoia, fear and stigmatization. It can also result in people being left unprotected or more vulnerable to the virus. Get verified facts and advice from trusted sources like your local health authority, the UN, UNICEF, WHO.
If you see content online that you believe to be false or misleading, you can help stop it spreading by reporting it to the social media platform.
Do the COVID-19 vaccines contain any animal products in them?
No, none of the WHO-approved COVID-19 vaccines contain animal products.
How can I protect my family until we are all vaccinated?
Safe and effective vaccines are a game changer, but even once vaccinated we need to continue taking precautions for the time being to protect ourselves and others. Variants like Omicron have proven that although COVID-19 vaccines are very effective at preventing severe disease, they’re not enough to stop the spread of the virus alone. The most important thing you can do is reduce your risk of exposure to the virus. To protect yourself and your loved ones, make sure to:
- Keep a physical distance from others in public places.
- Avoid poorly ventilated or crowded spaces.
- Open windows to improve ventilation indoors.
- Try and focus on outdoor activities if possible.
- Wash your hands regularly with soap and water or an alcohol-based hand rub.
- If you or a family member has a fever, cough or difficulty breathing, seek medical care early and avoid mixing with other children and adults.
What are the benefits of getting vaccinated?
Vaccines save millions of lives each year and a COVID-19 vaccine could save yours. The COVID-19 vaccines are safe and effective, providing strong protection against serious illness and death. WHO reports that unvaccinated people have at least 10 times higher risk of death from COVID-19 than someone who has been vaccinated.
It is important to be vaccinated even if you already had COVID-19. Getting vaccinated is a safer way for you to develop immunity from COVID-19 than getting infected.
The COVID-19 vaccines are highly effective, but no vaccine provides 100 per cent protection. Some people will still get ill from COVID-19 after vaccination or pass the virus onto someone else.
Therefore, it is important to continue practicing safety precautions to protect yourself and others, including avoiding crowded spaces, physical distancing, and hand washing.
What are the side effects of COVID-19 vaccines?
Vaccines are designed to give you immunity without the dangers of getting the disease. Not everyone does, but it’s common to experience some mild-to-moderate side effects that go away within a few days on their own.
Some of the mild-to-moderate side effects you may experience after vaccination include:
- Arm soreness at the injection site
- Mild fever
- Fatigue
- Headaches
- Muscle or joint aches
- Chills
- Diarrhoea
You can manage any side effects with rest, staying hydrated and taking medication to manage pain and fever, if needed.
If any symptoms continue for more than a few days then contact your healthcare provider for advice.
Read more on COVID-19 vaccines’ side effects.
More serious side effects are extremely rare, but if you experience a more severe reaction, then contact your healthcare provider immediately.
How do I find out more about a particular COVID-19 vaccine?
You can find out more about COVID-19 vaccines on WHO’s website.
Can I stop taking precautions after being vaccinated?
Keep taking precautions to protect yourself, family, and friends, even after getting vaccinated. The COVID-19 vaccines are highly effective against serious illness and death, but no vaccine is 100% effective.
The vaccines offer less protection against infection from the Omicron variant, which is now the dominant variant globally, but remain highly effective in preventing hospitalization, severe disease, and death.
In addition to vaccination, it remains important to continue practicing safety precautions to protect yourself and others. These precautions include avoiding crowded spaces, physical distancing, and hand washing.
Can I still get COVID-19 after I have been vaccinated? What are ‘breakthrough cases’?
A number of vaccinated people may get infected with COVID-19, which is called a breakthrough infection. In such cases, people are much more likely to only have milder symptoms. Vaccine protection against serious illness and death remains strong.
With more infectious virus variants such as Omicron, there have been more breakthrough infections. That’s why it's recommended to continue taking precautions such as avoiding crowded spaces, and washing your hands regularly, even if you are vaccinated.
And remember, it’s important to receive all of the recommended doses of vaccines to have the maximum protection.
How long does protection from COVID-19 vaccines last?
According to WHO, the effectiveness of COVID-19 vaccines wanes around 4-6 months after the primary series of vaccination has been completed. Taking a booster to strengthen your protection against serious disease is recommended.
Do I need to get a booster shot?
Booster doses play an important role in protecting against severe disease, hospitalization and death.
WHO recommends that you take all COVID-19 vaccine doses recommended to you by your health authority, including a booster dose if recommended.
Data shows that a booster shot plays a significant role in boosting waning immunity and protecting against severe disease from highly transmissible variants like Omicron.
An additional second booster shot is also recommended for some groups of people, 4-6 months after the first booster. That includes older people, those who have weakened immune systems, pregnant women and healthcare workers.
What do we know about the bivalent COVID-19 booster doses that have been developed to target Omicron?
Bivalent COVID-19 booster shots have now been developed with both the original strain of the coronavirus and a strain of Omicron. These have been designed to better match the Omicron subvariants that have proven to be particularly transmissible. Lab studies have shown that these doses help you to mount a higher antibody response against Omicron. Both Moderna and Pfizer have developed these bivalent vaccines, and some countries have now approved their use.
And it’s important to note that the original COVID-19 vaccines continue to work very well and provide strong protection against severe illness from Omicron.
Can I receive different types of COVID-19 vaccines?
Yes, however, policies on mixing vaccines vary by country. Check with your local health authorities for guidance and speak with your healthcare provider if you have any questions on what is best for you.
Could a COVID-19 vaccine disrupt my menstrual cycle?
Some people have reported experiencing a disruption to their menstrual cycle after getting vaccinated against COVID-19. Although data is still limited, research is ongoing into the impact of vaccines on menstrual cycles.
Speak to your healthcare provider if you have concerns or questions about your periods.
How do I talk to my kids about COVID-19 vaccines?
News about COVID-19 vaccines is flooding our daily lives and it is only natural that curious young minds will have questions – lots of them. Read our explainer article for help explaining what can be a complicated topic in simple and reassuring terms.
It’s important to note that from the millions of children that have so far been vaccinated against COVID-19 globally, we know that side effects are very rare. Just like adults, children and adolescents might experience mild symptoms after receiving a dose, such as a slight fever and body aches. But these symptoms typically last for just a day or two. The authorized vaccines for adolescents and children are very safe.
My friend or family member is against COVID-19 vaccines. How do I talk to them?
The development of safe and effective COVID-19 vaccines is a huge step forward in our global effort to end the pandemic. This is exciting news, but there are still some people who are skeptical or hesitant about COVID-19 vaccines. Chances are you know a person who falls into this category.
We spoke to Dr. Saad Omer, Director at the Yale Institute for Global Health, to get his tips on how to navigate these challenging conversations.
