Is there a vaccine against COVID-19?
There are ten World Health Organization (WHO)-approved COVID-19 vaccines for which WHO issued recommendations for use. They are produced by the following manufacturers: Pfizer/BioNTech, AstraZeneca/Oxford, Janssen, Moderna, Sinopharm, Sinovac, Bharat, Novavax, Casino and Valneva. WHO continues to evaluate other vaccines in clinical and preclinical trials. In addition, the national regulatory authority (NRA) of some countries has authorized the use of other COVID-19 vaccines in their territory.
For more information, visit:
- Get the .
- For more information on all COVID-19 vaccines in development, see the .
How is a vaccine licensed for use?
- Through the WHO Emergency Use List (EUL): The WHO EUL procedure is a risk-based procedure for evaluating and listing unlicensed vaccines, therapies and in vitro diagnostics with the objective of accelerating the availability of these products to people affected by a public health emergency. In addition, it allows countries to expedite their own regulatory approval to import and administer COVID-19 vaccines. After rigorous evaluation of the clinical data provided by vaccine manufacturers, the EUL process decides whether WHO will issue a recommendation for the use of a specific COVID-19 vaccine in all countries of the world. If there are doubts about its safety or efficacy, the vaccine will not receive a recommendation.
- Through a national regulatory authority (NRA): Manufacturers of COVID-19 vaccines provide information on the results of clinical trials to demonstrate the efficacy of these vaccines in preventing the disease. National regulatory agencies then analyze these data and issue a license for the vaccine to be used in their territory. Without this national authorization, the vaccine cannot be used in the country. The efficacy and safety of vaccines continue to be closely monitored even after their introduction in a country.
Learn more:
How do mRNA vaccines work and are they new?
Messenger RNA (mRNA) vaccines teach our cells to make a protein that will trigger an immune response in our bodies. Like all vaccines, mRNA vaccines benefit people by giving them protection against diseases such as COVID-19, without risking the potentially serious consequences of getting sick. The technology of mRNA vaccines is new but well understood. Researchers have been studying and working with them for decades for other diseases such as influenza and Zika.
More information:
Are vaccines against variant viruses effective?
The WHO-recommended COVID-19 vaccines are highly effective in preventing severe illness, hospitalization, and death against all strains of SARS-CoV-2 virus (i.e., the virus that causes COVID-19), including the omicron variant and its sub-lineages. In addition, vaccines are very effective in reducing transmission of the virus, although they may not completely prevent infection.
Through global laboratory networks, the evolution of the SARS-CoV-2 virus continues to be monitored to rapidly identify the emergence of any new variants. WHO is in close communication with researchers, health officials and scientists to learn how these variants may affect vaccine properties.
More information:
Why do some vaccinated people still get sick?
Vaccines against COVID-19 are very effective and have made an important contribution to limiting transmission of the SARS-CoV-2 virus worldwide. However, no vaccine is 100% effective in preventing the disease. There will always be a small percentage of fully vaccinated people who will become ill. However, symptoms are usually mild or absent in vaccinated persons who become infected.
In addition, full protection from the vaccine begins 14 days after administration of the second dose of vaccine. Thus, a person may contract SARS-CoV-2 virus immediately before or shortly after receiving the COVID-19 vaccine and, therefore, will not be fully protected despite vaccination during this period.
Where can I get vaccinated against COVID-19?
Since COVID-19 vaccines are available in all countries and territories of the Americas, you can access them through your National Immunization Program. Contact your nearest health center or pharmacy for more information.
How long does the immunity provided by the COVID-19 vaccine last?
Available data suggest that most persons who receive a primary series of COVID-19 vaccine (i.e., three doses) develop an immune response that provides 6-12 months of protection against reinfection. For more information on SAGE recommendations on dosing and boosters refer to the WHO Update of Recommendations on COVID-19 Vaccination.
More information:
Is there a WHO COVID-19 vaccination certificate?
PAHO/WHO does not keep a record of persons who have been vaccinated in each country. Therefore, WHO does not issue an international certificate of vaccination or a prophylaxis card for vaccines received against COVID-19. The vaccination document issued by the government of each country is the only proof of vaccination against COVID-19 that is currently available.
What should I do if I plan to travel abroad?
An international traveler must follow the health requirements issued by the countries to which he/she is traveling.
What is the process for developing a vaccine that is safe and effective?
All vaccines undergo three phases of clinical trials before they are approved for use in the population. The trial phases ensure the safety and ability of the vaccine to protect against disease (i.e., efficacy). In addition, clinical trials provide answers to other questions, such as the population groups to which the vaccine can be administered, the number of doses needed and the required interval between doses.
More information:
Why are vaccine clinical trials sometimes discontinued?
Ensuring product safety is the primary objective of clinical trials of any vaccine or therapeutic drug. When a trial participant experiences a health event after vaccination (which may or may not be related to the vaccine), the study protocol requires an investigation to understand the cause of the event. While the investigators review what happened, the trial may be temporarily suspended to prevent any new events.
Vaccine safety continues to be monitored even after a vaccine begins to be used in the general population. If one or more health events are reported after vaccination, and the initial investigation reports any concerns with vaccine safety, administration of this vaccine may be suspended until more information can be collected and analyzed. This is a standard procedure that can affect any vaccine, not just COVID-19 vaccines. Vaccine administration is resumed as soon as all tests report that the vaccine is safe for use.
How were clinical trials of the COVID-19 vaccine accelerated?
Before any vaccine is approved for use in the general population, it must undergo three phases of clinical trials. The vaccines developed against COVID-19 followed the same rigorous phases. Each phase evaluates the safety and efficacy of the vaccine, and the trial does not proceed until all requirements are met. Once the vaccine is approved for use in the general population, monitoring of safety and efficacy continues.
In the case of the COVID-19 vaccines, the administrative/bureaucratic process was expedited to ensure that the vaccines could reach the public as quickly as possible. The safety and efficacy evaluation of each vaccine met all the criteria for rigorous evaluation, and this process was never accelerated to meet deadlines.
More information:
Are COVID-19 vaccines safe?
Yes, vaccine safety is always the top priority for WHO and national regulatory agencies. All vaccines go through rigorous clinical trial phases before they are approved for use in the population. These trials are intended to ensure the safety and ability of the vaccine to protect against disease.
COVID-19 vaccines follow these same strict safety and efficacy requirements. They are not recommended, approved or introduced into countries until their safety has been demonstrated to national regulatory agencies. Once approved, the administration of COVID-19 vaccines continues to be monitored to immediately identify any concerns regarding the safety of the vaccine. This monitoring is a normal part of immunization programs and is performed for all vaccines.
More information:
Are mRNA vaccines safe?
Yes, mRNA vaccines are subject to the same rigorous safety standards as other vaccines. Vaccines are not approved or released for use in the general population until all safety data have been thoroughly reviewed by national regulatory authorities.
More information:
How are countries monitoring and addressing Events Suspected to be Attributable to Vaccination or Immunization (ESAVI) with COVID-19 vaccines?
With the support of PAHO, the countries of the Americas developed national surveillance systems to identify and respond rapidly to any Events Suspected of Being Attributable to Vaccination or Immunization (ESAVI). The objective of this surveillance network is to enable Ministries of Health to investigate any adverse event that occurs after vaccination (regardless of whether it is associated with the vaccine).
More information:
Do COVID-19 vaccines have long-term negative effects?
After receiving any vaccine, your body will break down its components within a few days. What remains is your body's memory of how to fight the virus. Many people do not experience any discomfort. Others experience some side effects within the first few days of receiving the dose. These effects are usually mild (e.g., headache, tiredness, pain, swelling and irritation at the injection site) and temporary. If the side effect lasts longer than 10 days, it is recommended to consult a physician. More serious or long-lasting side effects from COVID-19 vaccines are extremely rare. If you experience shortness of breath, chest pain, confusion, loss of speech or mobility after the vaccine, contact your health care provider immediately.
More information:
What should I know about thrombosis or Thrombosis with Thrombocytopenia Syndrome (TTS)? Are some people more at risk?
Thrombosis with Thrombocytopenia Syndrome (TTS) is a condition where a person has both severe venous or arterial thrombosis (confirmed by imaging, surgical or pathological tests) and new-onset thrombocytopenia (platelet count below 150,000/μL). This is an extremely rare event that can occur after vaccination with COVID-19 vaccines produced by AstraZeneca or Janssen.
WHO concluded that the benefit of vaccination to protect against COVID-19 far outweighs the risks of developing TTS, as the condition is rare and can be easily treated if the person seeks care early. However, people who have had blood clots associated with TTS after the first dose of vaccine should not receive the second dose with the same COVID-19 vaccine.
Is there a risk of heart inflammation (myocarditis or pericarditis) from COVID-19 mRNA vaccines?
mRNA vaccines are used to protect millions of people against COVID-19. Data are available from both clinical trials and country surveillance programs on their efficacy and safety. In some people, mild side effects are expected for 1-2 days after vaccination. These are a normal sign that the body is developing protection.
Rarely, cases of myocarditis (i.e., inflammation of the heart muscle) and pericarditis (i.e., inflammation of the membrane surrounding the heart) have been reported following a dose of COVID-19 mRNA vaccine (produced by Pfizer or Moderna). Symptoms of myocarditis and pericarditis are usually mild. Immediate treatment with medication and rest can help prevent long-term heart damage. If you experience new and persistent chest pain, shortness of breath, or have a rapid or pounding heartbeat within a few days of vaccination with an mRNA vaccine, contact your physician immediately.
WHO continues to assert that the benefits of mRNA vaccines far outweigh the risk of myocarditis and pericarditis, as this event is rare and easily treatable.
Is there a risk of Guillain-Barré syndrome from COVID-19 vaccines?
Guillain-Barré syndrome (GBS) is a rare disorder of the immune system that causes muscle weakness, pain or numbness and, in more severe cases, paralysis. GBS can be due to a variety of causes (including infections) and occurs most often in males and people aged 50 years or older. Rarely, cases may occur by chance immediately after vaccination.
In very rare cases, symptoms of GBS have been reported in persons who received COVID-19 vaccines produced by Janssen or AstraZeneca. In these situations, the person should seek immediate medical attention if they develop weakness/tingling and paralysis in the extremities that may progress to other parts of the body including the chest and face. Symptoms may include difficulty walking; difficulty with facial movements; double vision or inability to move the eyes; or difficulty controlling bladder or bowel functions.
Despite the possibility of this event, the WHO continues to assert that the benefits of the vaccines produced by AstraZeneca and Janssen far outweigh the risk of GBS, as this event is very rare.
More information:
What does the term variant-containing vaccine means?
The term variant-containing vaccine indicates that the vaccine helps protect against a new variant of COVID-19.
The following variant-containing vaccines have been licensed for use as booster vaccines: the Pfizer-BioNTech and Moderna variant-containing bivalent mRNA vaccines, and the Sanofi-GSK Vidprevtyn Beta monovalent vaccine (CoV2 preSdTM-AS03 (B.1.351)).
For the primary series, any of the COVID-19 vaccines on the WHO Emergency Use List (EUL) may be used. Also, any of the EUL-approved COVID-19 vaccines or vaccines containing licensed variants can be used for booster vaccination.
WHO SAGE recommends that countries may consider using the BA.5 bivalent mRNA vaccine for the primary series.
Don't delay getting your booster dose now in favor of getting a bivalent vaccine later.
More information:
Who are the people in the high-priority group who should be protected against COVID-19?
High-priority individuals are those at highest risk of becoming seriously ill and dying from COVID-19. For them, a decrease in effectiveness, however small, increases the occurrence of severe illness and death. Therefore, they should be up-to-date with their COVID-19 vaccination schedule (primary series and booster doses). Especially, they should receive booster doses according to these recommendations:
Should receive an additional booster dose 6 months after the last dose:
- Oldest adults (over 75 years old)
- Older adults with comorbidities (60 to 75 years)
- Persons 6 months and older with compromised immune systems
- Pregnant people.
Should receive an additional booster dose 12 months after the last dose:
- Older adults (60 to 75 years old)
- Adults with comorbidities or severe obesity (18 to 59 years)
- First-line health care personnel.
Should people who have had COVID-19 continue to be vaccinated against it?
PAHO/WHO recommends that everyone who has had COVID-19 receive all recommended doses of COVID-19 vaccine, regardless of whether the person has had no symptoms or has been very ill. The vaccine further strengthens the body's immune system against COVID-19.
Can I be vaccinated against COVID-19 if I am currently infected with COVID-19?
If you have symptoms of COVID-19, or have been diagnosed with COVID-19, you may be vaccinated. However, you should follow local isolation guidelines before getting vaccinated to avoid infecting others. Therefore, it is best to wait until you recover to get vaccinated.
More information:
How long should I wait to get vaccinated after I have had COVID-19?
COVID-19 vaccines can be administered at any time, as long as the person is no longer infected with SARS-CoV-2 virus (with or without symptoms), to avoid infecting others by receiving the vaccine.
People who have previously had COVID-19 can become ill again. Therefore, PAHO/WHO recommends that people receive their required doses of vaccine as soon as possible, regardless of whether they have been sick with COVID-19.
Can I get other vaccines on the same day as the COVID-19 vaccine?
PAHO/WHO recommends that countries consider co-administration of COVID-19 vaccines (including variant-containing vaccines) with seasonal influenza vaccines.
According to several COVID-19 vaccine co-administration studies and derivatives of co-administration studies of other adult vaccines, COVID-19 vaccines can be administered at the same time as, or at any time before or after, other adult and adolescent vaccines, including live attenuated, inactivated, adjuvanted, or unadjuvanted vaccines.
When administered simultaneously, the vaccines should be injected at separate sites, preferably at different extremities.
More information:
Can pregnant people be vaccinated against COVID-19?
Pregnant people are at risk for COVID-19. Because their immune system changes throughout pregnancy, they are more vulnerable to respiratory infections such as COVID-19. If they become ill, they tend to develop more severe symptoms and their treatment may require longer hospitalization in intensive care units, a greater need for respiratory support, and a higher likelihood of dying compared to non-pregnant people of the same age and ethnicity.
WHO recommends that pregnant women receive three doses of COVID-19 vaccine, plus a booster dose within 6 months after their last dose.
Can breastfeeding mothers be vaccinated?
Infants can be vaccinated and because they are as likely to benefit from vaccination as other adults their age, and breastfeeding offers important health benefits for infants and their breastfed children. PAHO/WHO does not recommend interrupting breastfeeding because of vaccination.
Since none of the COVID-19 vaccines are live virus vaccines, they are biologically unlikely to pose a risk to the infant.
More information:
Can people with underlying diseases be vaccinated against COVID-19?
Severe COVID-19 disease, hospitalization and death have been associated with medical conditions such as hypertension, diabetes, asthma, and lung, liver or kidney disease.
WHO recommends that all persons aged 6 months or older who have comorbidities receive three doses of COVID-19 vaccine, plus a booster dose within 12 months after their last dose. Persons with comorbidities who are 60 years or older should receive this booster dose within 6 months after their last dose.
Can immunocompromised persons be vaccinated against COVID-19?
Severe COVID-19 disease, hospitalization and death have been associated with immunodeficiency conditions.
WHO recommends that all immunocompromised persons aged 6 months or older receive three doses of COVID-19 vaccine, plus a booster dose within 6 months after their last dose.
Since none of the COVID-19 vaccines are live virus vaccines, they are biologically unlikely to pose a risk to the individual.
Can people diagnosed with Guillain-Barré syndrome (GBS) be vaccinated against COVID-19?
GBS is a rare disorder of the immune system that causes muscle weakness, pain or numbness and, in severe cases, paralysis. GBS can be due to a variety of causes, including infections, and is most common in males and people ages 50 years or older. Cases may occur by chance immediately after vaccination.
Individuals who have had GBS in the past may receive the COVID-19 vaccine. To date, no cases of GBS have been reported following vaccination in participants in clinical trials of the COVID-19 mRNA vaccine.
For more information, visit:
Can children be vaccinated against COVID-19?
Although most COVID-19 vaccines are only approved for use in adults over 18 years, some countries have granted emergency use authorization for mRNA vaccines (produced by Pfizer and Moderna) for use in age groups 6 months and older.
WHO recommends that all immunocompromised persons aged 6 months and older receive three doses of COVID-19 vaccine, plus a booster dose within 6 months after their last dose.
WHO recommends that children and adolescents aged 6 months to 17 years with comorbidities that increase their risk of severe disease receive all three doses of COVID-19 vaccine.
WHO recommends that healthy children and adolescents between 6 months and 17 years of age should be vaccinated with the primary series and with a booster dose depending on the country context.
PAHO/WHO does not recommend additional booster doses for children and adolescents.
More information:
Can people with allergies or immune system problems be vaccinated against COVID-19?
If a person suffers from allergies that are not related to a component of the COVID-19 vaccine to be received, the vaccine may be administered.
A person with a history of anaphylaxis to any other vaccine or injectable therapy (i.e., intramuscular, intravenous, or subcutaneous vaccines or therapies) may be vaccinated against COVID-19. However, a health care professional should perform a risk assessment prior to vaccination. In addition, these individuals should be observed for 30 minutes after vaccination in healthcare settings where anaphylaxis can be treated immediately.
Persons with an immediate non-anaphylactic allergic reaction to the first dose (i.e., urticaria, angioedema without respiratory signs or symptoms occurring within 4 hours of administration), should not receive additional doses of the same COVID-19 vaccine. If a second dose of the same vaccine is administered, the patient should be closely observed for 30 minutes after vaccination in a healthcare setting where severe allergic reactions can be treated immediately.
For more information:
Does the vaccine protect me from COVID-19?
COVID-19 vaccines protect you from becoming seriously ill or dying from COVID-19 by teaching your body to fight the SARS-CoV-2 virus (which causes COVID-19). However, the vaccine may not fully protect you against infection although, once vaccinated, the illness is usually mild or asymptomatic.
To further limit the risk of infection, continue to apply social distancing, use of masks and hand washing in closed or poorly ventilated environments, especially when in contact with a person showing symptoms of COVID-19.
More information:
If I have not experienced any side effects after vaccination, does the vaccine still work?
Even if you do not experience any side effects after vaccination (e.g., headache, tiredness, pain, swelling, and irritation at the injection site), it does not mean that the COVID-19 vaccine did not produce protection. All COVID-19 vaccines have been shown to be safe and effective.
If the vaccine I received requires more than one dose, do I really need the full series?
All approved vaccines require people to have a second injection and a booster dose within a certain period of time. Administering this second and booster dose at the recommended intervals improves your body's immune response to the virus. Not receiving these additional doses means that you will not be fully protected against the disease.
If I have already received three doses, do I really need a booster dose?
A booster dose is an additional dose given to a person who has completed a primary vaccination series (i.e., the first three doses) after the vaccine has become so weak that it no longer provides sufficient protection.
PAHO/WHO recommends that the following groups should receive an additional booster dose 6 months after the last dose:
- Oldest adults (over 75 years old)
- Older adults with comorbidities (60 to 75 years)
- Persons 6 months and older with compromised immune systems
- Pregnant people.
PAHO/WHO recommends that the following groups should receive an additional booster dose 12 months after the last dose:
- Older adults (60 to 75 years old)
- Adults with comorbidities or severe obesity (18 to 59 years)
- First-line health care personnel.
Do booster vaccines work if I have already received the COVID-19 vaccine?
Research has shown that people who received booster vaccines were much less likely to test positive than those who had received only two doses.
Is it advisable to mix different brands of vaccines?
It is safe and effective for you to receive a second, third or fourth dose of a different COVID-19 vaccine than the one used as the first dose. If you are offered another type of vaccine, you may continue to be vaccinated. WHO considers two doses of any vaccine on the WHO Emergency Use List (EUL) to constitute a complete primary series. See the full list of WHO EUL COVID-19 vaccines .
Read more about this .
Will COVID-19 vaccination be required every year?
Researchers continue to study the available data on the need and timing of additional long-term booster doses to maintain protection against COVID-19.
It is not yet known whether vaccination against COVID-19 should be given periodically over the years. As more studies are completed, WHO will be able to determine whether additional doses of vaccination are needed and how often.
Can I donate blood after receiving the COVID-19 vaccine?
Yes, blood can be donated immediately after receiving the COVID-19 vaccine.
Do COVID-19 vaccines contain any dangerous and toxic ingredients?
Although the ingredients listed on vaccine labels may seem alarming (e.g., thiomersal, aluminum, formaldehyde), these substances occur naturally in the human body, in the food we eat and in the environment. The amounts of components contained in vaccines are extremely small and do not harm the body.
Read more:
Does the vaccine produced by AstraZeneca contain any sulfur or traces of sulfur?
No, the COVID-19 vaccine produced by AstraZeneca does not include sulfur in any amount.
More information:
Can COVID-19 vaccines cause magnetism in me?
No. COVID-19 vaccines cannot and will not make you magnetic, even at the injection site. The vaccines are free of metals that could cause a magnetic attraction in your body.
Is it better to get COVID-19 naturally than to be vaccinated against it?
No. Vaccines create immunity without the detrimental effects that COVID-19 disease can have, including long-term effects and death. Allowing the disease to spread could cause millions of deaths and even more people living with the long-term effects of the virus.
Do COVID-19 vaccines contain human fetal tissue cells?
Vaccines do not contain fetal cells.
In the production process of some vaccines, cell lines from cells recovered from fetal tissues obtained from abortions performed in Sweden and England more than 40 years ago have been used. These abortions were voluntary, complied with the legislation of the countries and were not performed for the purpose of generating cell lines to produce vaccines.
Cell lines have revolutionized scientific research by allowing the study in the laboratory of various biological processes that could occur in some living organisms. Cell lines are generated from cells obtained from tissues (human, animal or plant) and cultured in a laboratory, for example, to investigate new drugs or vaccines. Several types of cell lines have been used in the production of vaccines, such as those for rubella, chickenpox, hepatitis A, rabies and, recently, in some of the COVID-19 vaccines.
Scientists use cell lines because viruses, unlike bacteria, need cells to grow and multiply. Cell lines are necessary for viruses to grow and multiply so that they can be studied in the laboratory. Cell lines developed from fetal tissue have the advantage that they can grow and multiply indefinitely under certain laboratory conditions, because fetal cells are in a process of continuous differentiation and growth. This makes them preferable for research to other primary cell lines or cultures that can only be reproduced a limited number of times.
Although some vaccines use cell lines in their research and production process, no vaccine contains fetal cells.
Do people vaccinated against COVID-19 shed the virus?
No person who received an approved COVID-19 vaccine discharges or releases any of the vaccine components.
Will certain foods or beverages have any effect on the efficacy of the COVID-19 vaccine?
No. The efficacy or safety of the vaccine is not affected by any food or beverage consumed before or after administration of the COVID-19 vaccine.
What effects do COVID-19 vaccines have on menstrual periods?
Individuals can receive the COVID-19 vaccine at any time during their menstrual period.
There have been reports of individuals experiencing a disruption of their menstrual cycle after being vaccinated against COVID-19. Several large-scale studies on the impact of vaccines on menstrual cycles are ongoing.
If you have any doubts or questions about your menstruation, talk to your health care professional.
More information:
- You can find about studies of COVID-19 vaccines and the menstrual cycle and .
Can being around a person vaccinated against COVID-19 affect the menstrual period of a non-vaccinated person?
If a person has been vaccinated against COVID-19, it will have no effect on another person's menstrual period.
Can COVID-19 vaccines affect my ability to have children in the future?
Studies of licensed COVID-19 vaccines have shown that receiving them has no effect on fertility in men or women. In fact, some participants in the clinical studies became pregnant during the studies. No vaccine suspected of affecting a person's ability to conceive has ever been or will ever be approved.
Does the COVID-19 vaccine cause breast cancer?
WHO and national regulatory agencies have never approved any vaccine suspected of causing breast cancer, or any other type of cancer. People who have received the COVID-19 vaccine may have swollen lymph nodes (lymphadenopathy) in the armpit near the site where they received the shot. This swelling is a normal sign that your body is building protection against COVID-19. However, it is possible that this swelling can cause a false reading on a mammogram. Some experts recommend getting a mammogram before getting vaccinated or waiting 4 to 6 weeks after getting vaccinated.
For more information:
Can COVID-19 vaccines increase breast size?
COVID-19 vaccines do not increase breast size. Some people who receive the COVID-19 vaccine may have swollen lymph nodes under the arm where the vaccine was given. However, this occurs with all vaccines, not just the COVID-19 vaccine.
This information on lymph node inflammation is provided by .
Is MPOX caused by the COVID-19 vaccine?
COVID-19 vaccines do not cause MPOX disease. MPOX is a zoonotic viral disease and is transmitted from person to person primarily through direct or indirect contact with the rash or with body fluids (e.g., fluid, pus, or blood from skin lesions).
Read more about here.