Patient safety is central to the research and development of every vaccine. Vaccine makers must follow very strict scientific and health authority processes to bring a new vaccine to the public, even during the current pandemic.

Like all vaccines, the COVID-19 vaccines go through many stages of approval, including:

• Exploratory "proof of concept" stage.
• Pre-clinical stage (often include animal studies).
• Clinical development (which include human clinical trial phases 1-3).
• Health authority review, authorization or approval.
• Manufacturing and quality control.

Like with all other vaccines and medicines, COVID-19 vaccines are only authorized or approved for use with the general public after:

• Clinical trials thoroughly test them with tens of thousands of people.
• An independent group of experts with health authorities carefully review all the scientific and clinical trial data results and authorize it for use with the general public only if the benefits of the vaccine outweigh the known and possible risks of getting a COVID-19 infection.

Clinical trials also help find serious medical problems (called serious adverse events) that may happen shortly after getting a vaccine. However, rare medical problems, and problems that only become apparent long-term, are likely to be spotted only after large groups of people get the vaccine. This is why researchers and health authorities will continually monitor their use to check that no safety concerns surface and the vaccines continue to work well in different groups of people over time. The health authorities also check for very rare side-effects or side-effects that may become apparent only after long-term use.

Vaccines have been saving lives for the last 200 years and have erased some of the world's most deadly diseases. Before any vaccine can be authorized or approved for use, clinical trials must first show the vaccines are safe and effective (work well). To be authorized or approved, the known and potential benefits of the vaccine must also outweigh the known and potential risks of the vaccine.

Health authorities review all the scientific and clinical trial data and decide if the vaccines can be authorized or approved for use in their region or countries. They review all the preclinical (such as animal research), clinical, and manufacturing process data, including the safety and efficacy (how well it works) data. These health authorities include regional regulatory authorities like the European Medicines Agency (EMA) in the European Union, and national regulatory authorities such as the Food and Drug Administration (FDA) in the U.S. and the Pharmaceuticals and Medical Devices Agency (PMDA) in Japan.

COVID-19 vaccines follow internationally agreed standards for vaccine development and approval. Like all new medicines or treatments, vaccines must pass a thorough set of tests that show their quality, safety, and efficacy (how well it works) in hundreds of thousands of volunteers before being approved or authorized by independent, scientific experts who work for health authorities.

Read more about the COVID-19 vaccine candidates that are currently being studied in clinical trials and which COVID-19 vaccines have been authorized or approved in different countries.

Due to the public health emergency, the authorization and manufacturing of COVID-19 vaccines has been quicker than with previous vaccines. There has been a unique level of preparation and collaboration among researchers, vaccine makers, researchers, regulators, governments and health authorities, as well as unprecedented funding for the vaccine development and manufacturing. These partnerships accelerated the safe and effective development and authorization of COVID-19 vaccines, without compromising on any of the safety or authorization processes.

Other factors that shortened the development timeline include:

• Vaccine makers carried out clinical trials and making vaccines in parallel instead of doing one after the other. This avoided long wait times between trials. Given the high spread of the virus, it has been easier to recruit clinical trial volunteers and easier to test the efficacy (how well it works to prevent infection) of vaccines.
• Vaccine makers gave health authorities access to the clinical trial results throughout the process (“a rolling review”), rather than waiting until the end, to help them carry out ongoing reviews of results. Even before final authorization, vaccine makers started manufacturing to shorten the time it would take to distribute vaccines.
• Vaccine makers have worked around the clock to update facilities and hire and train more staff to make the huge number of vaccines needed. Suppliers making vials, syringes, and stoppers are working overtime and in close partnership with the vaccine makers.
• Health authorities set up dedicated task forces made up of independent experts and rapid review processes to evaluate high-quality applications from vaccine makers. This allows the shortest possible timeframes while ensuring robust scientific opinions.
• Financial support from governments has, in some cases, allowed the above to happen more quickly than with other vaccines.

Hundreds of thousands of participants worldwide have volunteered to take part in COVID-19 vaccine clinical trials. Clinical trials are designed to test vaccines in people of all races and genders, different ages, and those with underlying health problems, including those with a higher risk of severe illness from COVID-19. This helps increase the understanding of safety and the efficacy (how well it works) of COVID-19 vaccines across different groups of people in different parts of the world. The more people who can get an authorized or approved vaccine, the more successful we will be in helping to stop the spread of the COVID-19 virus and ending the pandemic.

Vaccine makers support independent expert review of clinical trial data for all COVID-19 vaccines. They are also committed to transparently publishing clinical trial results that supported the approval of the vaccines by health authorities. Many of the vaccine makers have published their clinical trial results online and in peer reviewed medical journals such as The Lancet and The New England Journal of Medicine.

Transparency is one of the most important ways to inform the public about – and build greater confidence in – the process to develop a vaccine for COVID-19. Government agencies, like the FDA, EMA and CDC, have routinely released key information and held open meetings so that public feedback can help inform their decision-making.

Vaccine manufacturers have also taken steps to provide greater transparency within the COVID-19 vaccine development process. For example, it is common to pause a clinical trial if there are any safety questions which emerge, but they are rarely reported publicly. Several companies decided to publicly share any clinical pauses of COVID-19 vaccine clinical trials which occurred. This has helped keep the public informed of any bumps in the road to develop a vaccine and shows the vaccine clinical trial and development process of checks and balances is working appropriately.

Billions of people around the world have now received a COVID-19 vaccine. Some people have no side effects at all. Others have reported mild and temporary side effects like swelling, redness, fever, headache, fatigue, and nausea. Severe medical reactions can happen but are extremely rare.

The most common side effects are mild and temporary and most reactions happen shortly after getting the vaccine. This is why healthcare workers often ask you to stay in their office after you get a vaccine so that they can watch for immediate reactions after the administration of the vaccine.

For the COVID-19 vaccines that are currently being used broadly, clinical trials and real-life data have shown that side effects are similar to those of other vaccines and include:

• A sore arm where you got the shot.
• Feeling tired.
• A headache.
• Feeling achy.

If you have any of these side effects, they are likely to last no longer than a week. But if they do get worse or you are concerned, call your doctor. More information can be found in patient leaflets.

Remember, COVID-19 vaccines are only authorized or approved for use with the general public after:

• Clinical trials thoroughly test them with hundreds of thousands of people
• An independent group of experts with health authorities carefully review all the scientific and clinical trial data results and authorize it for use with the general public only if the benefits of the vaccine outweigh the known and possible risks of getting vaccinated.

As for all vaccines and medicines, independent health authorities continue to monitor the vaccine’s safety and effectiveness throughout its use (a process called pharmacovigilance) and provide the public with the latest information.

Please consult a healthcare professional for more information and follow the vaccination guidelines in place in your country.

As of July 2022, over 12 billion vaccine doses have been given to people around the world. COVID-19 vaccines are likely the most closely monitored product in the world today. It’s important that everyone who gets vaccinated feel confident the vaccine they receive is safe. That’s why health authorities continue to monitor the long-term safety of all vaccines even after the vaccines have been authorized for use with the general public. This monitoring process is called pharmacovigilance.

Clinical trials help find any mild to serious side effects that can happen shortly after getting a vaccine in a limited number of clinical trial volunteers. However, rare serious medical problems, are more likely to be spotted after larger groups of people get vaccinated. This is why researchers and health authorities, just like with other vaccines and medicines, continue to closely watch people who have received a COVID-19 vaccine.

Severe medical problems (like allergic reactions, blood clots, or heart inflammation) following COVID-19 vaccination are extremely rare. You’re at a higher risk of serious illness, hospitalization, or death from a COVID-19 infection than from any possible vaccine side effects or reactions.

As for all vaccines, independent health authorities continue to monitor the vaccine’s safety and effectiveness and provide the public with the latest information. For example, when some people reported blood clots and low blood platelets after getting the COVID-19 vaccine, researchers studied the problem and found it to be very rare. Independent health authorities found that the benefits of the vaccines in preventing COVID-19 continue to outweigh the risks of any side effects or severe reactions.

Similarly, when reports of myocarditis and pericarditis (inflammation of the heart muscle or lining) were received following COVID-19 vaccination, independent health authorities reviewed the evidence. They concluded that although myocarditis and pericarditis can occur in very rare cases following COVID-19 vaccination, given the risk of COVID-19 illness and related complications and as scientific evidence shows that vaccines reduce deaths and hospitalizations due to COVID-19, the benefits of all authorised COVID-19 vaccines continue to outweigh their risks, including the possible risk of myocarditis or pericarditis. In fact, some recent scientific studies have shown that those who are unvaccinated and get infected with the COVID-19 virus, are more likely to develop myocarditis than those who have received the vaccine.

Remember, getting vaccinated is a better way to build immunity than catching the virus and people are more likely to get sick from the SARS-CoV-2 virus than from getting the vaccine. COVID-19 can cause serious, long-term, life-threatening health problems or death, even in young healthy people, and there is no way to know how it will affect you. Also, if you get the virus, you could spread it to friends, family, and other people around you.

Please consult a healthcare professional for more information and follow the vaccination guidelines in place in your country.

No, genetic vaccines for COVID-19 do not affect or interact with your DNA in any way. mRNA is not the same as DNA, and it cannot combine or interfere with your DNA to change your genetic code. mRNA vaccines never reach a cell’s nucleus, where your DNA is housed inside the cell.

mRNA COVID-19 vaccines contain a small part of the virus’s genetic code (RNA) to trigger an immune response. While mRNA vaccines are a newer type of vaccine, they have been studied for the past two decades.

COVID-19 mRNA vaccines tell your cells to make a harmless piece of what is called the “spike protein.” The spike protein is found on the surface of the virus that causes COVID-19. Your immune system makes antibodies in response to the spike protein. It also creates a memory for this response, so your body can fight off SARS-CoV-2 in the future. The mRNA is destroyed shortly after being “read” by your cells and does not linger in your body.

No. You cannot get the COVID-19 illness from the COVID-19 vaccine. Just like you will not get measles from a measles vaccine.

When a virus is used to make a vaccine, it will not make you sick. It prompts your immune system to “learn” to recognize the virus and teaches it to build defenses to help protect you from getting the disease in the future.