Frequently Asked Questions about COVID-19 Vaccines

NEW Updated on January 7, 2021

As the COVID-19 vaccine is introduced, many people have questions about development, safety, access, cost, and other common concerns. This page provides information about what scientists do and do not know yet about the vaccines, drawing from the World Health Organization, the Ministry of Health and Family Welfare, Government of India, the United States Centers for Disease Control and Prevention, and other trusted sources. Some of this language is used word for word, and other language is paraphrased. We would like to acknowledge the hard work of these organizations in compiling this information.

Getting vaccinated is one of many steps you can take to protect yourself and others from COVID-19.  Other recommendations including the use of face masks, distancing and washing hands should continue to be followed to reduce your chance of being exposed to the virus or spreading it to others. Here is a illustrative guide to COVID-19 appropriate behaviours published by the MoHFW.

If you cannot find the information you are looking for on this page, you are invited to submit your own questions through this form and our team will look into the answers.


Vaccine Development

How does the COVID-19 vaccine work?

There are currently multiple COVID-19 vaccines being developed, tested and approved. They are all meant to teach the body’s immune system to safely recognize and block the coronavirus. The various types include:

  • mRNA vaccines, which contain synthetic mRNA, which is information used to make a coronavirus spike protein. This protein alone cannot cause COVID-19. Our cell uses this mRNA to make the viral protein which then causes our immune system to make antibodies to fight the virus when it is encountered.
  • Inactivated or weakened virus vaccines, which use a form of the virus that has been inactivated or weakened so it doesn’t cause disease, but still generates an immune response.
  • Protein-based vaccines, which use harmless fragments of proteins or protein shells that mimic the COVID-19 virus to generate an immune response, without causing COVID-19.
  • Viral vector vaccines, which use a genetically engineered virus to carry the genetic code (such as DNA) to generate a protein that prompts an immune response, without causing COVID-19.

Vaccine Types

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Why was the COVID-19 vaccine developed so much faster than other vaccines?

The vaccine process is happening faster because vaccine research and development, clinical trials, manufacturing, and plans for distribution are taking place at the same time. This method removes delays that occur when these processes are carried out one after the other. Steps to ensure safety are not being eliminated.

Vaccine Safety

How are vaccines tested?

Possible vaccines go through an intensive testing process.  Testing includes careful examination of the vaccine and its ingredients.  These tests evaluate the safety of the vaccine and how well it prevents a disease.  Tests are first done in research labs, and then if the vaccine looks effective and safe, researchers can apply to do clinical trials.  Clinical trials typically involve several thousand healthy volunteer participants in three phases with increasing numbers of participants in each phase.  Trials in all phases have to follow strict safety regulations that are set by national regulatory authorities that prioritize participant safety.  When vaccine manufacturers apply for approval for their vaccine, the results of all the clinical trials are considered.

How do we know the vaccine is safe?

The most commonly used vaccines we have today have been in use for decades, with millions of people receiving them safely every year. As with all these successful vaccines, COVID-19 vaccines have also undergone extensive and rigorous testing before being approved.  Scientists around the world have been working since early 2020 to develop the current possible COVID-19 vaccines and go through all of the testing processes to ensure they are safe. The vaccine safety is also monitored after the vaccines have been introduced which is called post-market surveillance. This ensures that the vaccines will continue to meet the same quality, safety and performance requirements as when they were initially introduced in the market.

Vaccine Development

Are there side effects to receiving the vaccine?

COVID-19 vaccination will help protect you from getting COVID-19. You may have some side effects, which are normal signs that your body is building protection. Common side effects include pain and swelling at the site of injection, and flu-like symptoms such as fever, chills, tiredness and headache. These should go away in a few days.

It has been seen that some people can develop allergic reactions after getting the COVID-19 vaccine. If you have ever had a severe allergic reaction to other vaccines or injectables, it is recommended that you speak to your doctor before getting vaccinated.

Is it safe for me to get the vaccine if I am pregnant or breastfeeding?

There is limited data on the safety of getting vaccinated against COVID-19 among people who are pregnant and breastfeeding, though scientists are planning to study this further. It is  recommended that you talk with your healthcare provider about the vaccine if you are pregnant or breastfeeding.

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Vaccine Access and Cost

Will there be enough vaccine for everyone?

The initial supply of the vaccine in India will be limited. For this reason, vaccination will be done in phases. In the initial phase, COVID-19 vaccine will be provided to the priority group: health care workers and front line workers. The 50 plus age group may also begin early based on vaccine availability. The eligible beneficiaries will be informed through their registered mobile number regarding the Health Facility where the vaccine will be provided and the schedule for the same. This will be done to avoid any inconvenience in registration and vaccination of beneficiaries. The goal is to get everyone vaccinated as supply becomes available. Even as the vaccine is becoming available, it is important to continue to follow the general recommendations including the use of face masks, distancing and washing hands.

Who will receive the COVID-19 vaccine first?

The Government of India has prioritized the most at risk/ high risk groups who will receive the vaccine first, this includes healthcare workers and frontline workers. Persons taking medicines for illnesses like cancer, diabetes, hypertension etc. are considered high risk category and shall also be receiving the COVID-19 vaccination. Two doses of vaccine, 28 days apart, need to be taken by an individual to complete the vaccination dose.

Common Concerns

Why do I need to get two doses of the vaccine?

The first dose will signal the production of ‘memory’ cells that will protect the body from future infection. A second dose will trigger those ‘memory’ cells again and will make the protection more effective.

Can I get COVID-19 from the vaccine?

No, the different types of vaccines have different materials in them that will signal our bodies to produce the proteins or antibodies to protect us from the virus. NONE of these vaccines contain the active virus.

The immune response that is initiated in the body might lead to symptoms, such as fever. This does not mean the person is infected with the virus. Learn more on how the Serum Institute and Bharat Biotech vaccines work.

It typically takes a few weeks for the body to build immunity after vaccination. That means it’s possible a person could be infected with the virus that causes COVID-19 just before or just after vaccination and get sick. This is because the vaccine has not had enough time to provide protection.

If I have already had COVID-19 and recovered, do I still need to get the COVID-19 vaccine when it becomes available?

There is not enough information currently available to say if or for how long after infection someone is protected from getting COVID-19 again. Early evidence suggests that this protection may not last very long, but it seems to vary by individuals. It is advisable to receive the complete schedule of the COVID-19 vaccine irrespective of the past history of infection with COVID-19. This will help in developing a strong immune response against the disease.

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

Persons with confirmed or suspected COVID-19 infection may increase the risk of spreading the virus to others at the vaccination site, hence infected individuals should defer vaccination for 14 days after symptoms resolution

Will a COVID-19 vaccine need to be given every year?

While testing has ensured that the COVID-19 vaccine is safe and effective at preventing illness in the short-term, we currently do not know how long its protection will last.  It is possible that protection will last for many years, but it is also possible that a COVID-19 vaccine will need to be given again in future years.  Repeat vaccination could be necessary if the vaccine’s protection decreases over time or if the virus that causes COVID-19 changes over time.

Do I need to wear a mask and avoid close contact with others if I have received two doses of the vaccine?

Yes. While experts learn more about the protection that COVID-19 vaccines provide under real-life conditions, it will be important for everyone to continue using all the tools available to us to help stop this pandemic. These tools include covering your mouth and nose with a mask, washing hands often, and staying at least 2 meters away from others. Together, the COVID-19 vaccine and everyone following the COVID-19 safety guidelines will offer the best protection from getting and spreading COVID-19.  Experts need to understand more about the protection that COVID-19 vaccines provide before deciding to change recommendations on steps everyone should take to slow the spread of the virus that causes COVID-19.

What are the ingredients in vaccines?

Today’s vaccines use only ingredients that are safe and effective. Each ingredient in a vaccine serves a specific purpose. For example, vaccine ingredients may:

  1. Help provide immunity (protection) against a specific disease
  2. Help keep the vaccine safe and long lasting
  3. Be used during the production of the vaccine
Ingredients provide immunity-

Vaccines include ingredients to help your immune system respond and build immunity to a specific disease. For example:

  • Antigens are very small amounts of weak or dead germs that can cause diseases. They help your immune system learn how to fight off infections faster and more effectively. The flu virus is an example of an antigen.
  • Adjuvants, which are in some vaccines, are substances that help your immune system respond more strongly to a vaccine. This increases your immunity against the disease. Aluminum is an example of an adjuvant.
  • Messenger ribonucleic acid (mRNA), in some new COVID-19 vaccines, is the active component that generates an immune response in the recipient.
Ingredients keep vaccines safe and long lasting-

Some ingredients help make sure a vaccine continues to work like it’s supposed to and that it stays free of outside germs and bacteria. For example:

  • Preservatives protect the vaccine from outside bacteria or fungus. Today, preservatives are usually only used in vials (containers) of vaccines that have more than 1 dose. That’s because every time an individual dose is taken from the vial, it’s possible for harmful germs to get inside. Most vaccines are also available in single-dose vials and do not have preservatives in them.
  • Stabilizers, like sugar or gelatin, help the active ingredients in vaccines continue to work while the vaccine is made, stored, and moved. Stabilizers keep the active ingredients in vaccines from changing because of something like a shift in temperature where the vaccine is being stored.
Ingredients used during the production of vaccines-

Some ingredients that are needed to produce the vaccine are no longer needed for the vaccine to work in a person. These ingredients are taken out after production so only tiny amounts are left in the final product. The very small amounts of these ingredients that remain in the final product aren’t harmful. Examples of ingredients used in some vaccines include:

  • Cell culture (growth) material, to help grow the vaccine antigens.
  • Inactivating (germ-killing) ingredients, like formaldehyde, to weaken or kill viruses, bacteria, or toxins in the vaccine.
  • Antibiotics, like neomycin, to help keep outside germs and bacteria from growing in the vaccine.
The claim that these vaccines contain a microchip or tracker is FALSE. The claim that these vaccines contain mercury is also FALSE.

For more information about the ingredients and possible allergens, please ask your provider before getting the vaccine.

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Please follow the links below for more information:

Ministry of Health & Family Welfare. Frequently Asked Questions on COVID-19 vaccine. Published December 2020.

World Health Organization

Center for Disease Control and Prevention

New York Times COVID-19 Vaccine Resources

Ministry of Health & Family Welfare. COVID-19 operational guidelines. Published 28 December 2020.


This material was curated by Viswanath Lab of Harvard Chan School of Public Health and the Dana-Farber Cancer Institute (DFCI) with the help of the Health Communication Core  of Dana-Farber/Harvard Cancer Center (DF/HCC). These are  not the official views of Harvard Chan  or DFCI. For any questions, comments or suggestions reach out to