How long does it take for the COVID-19 vaccine to work?
It typically takes two weeks after vaccination for the body to build protection (immunity) against the virus that causes COVID-19. That means it is possible a person could still get COVID-19 before or just after vaccination and then get sick because the vaccine did not have enough time to provide protection.
Coronavirus (COVID-19) vaccine: What to know
Millions of people have contracted the virus, and it has contributed to nearly 2 million deaths.
Researchers have been working around the clock to develop effective vaccines, which people started receiving in December 2020.
This article looks at the types of COVID-19 vaccine, how they work, their safety, and how to get one.
Which vaccines have approval?
Different vaccines are now available in various countries. In the United States, vaccines need approval from the Food and Drug Administration (FDA).
First, they need to pass through three phases of tests to prove that they are safe and effective. The last stage, phase 3, involves tens of thousands of participants.
At the time of writing, two vaccinesTrusted Source have FDA approval for use in the U.S.:
The Pfizer-BioNTech vaccine, developed in Germany, received FDA approval in the form of an emergency use authorization on December 11, 2020Trusted Source.
In a phase 3 trial involving more than 43,000 people, around half received a placebo and half received two doses of the vaccine, 21 days apart. The results showed that the vaccine was 95% effective at protecting against COVID-19.
The Moderna vaccine, developed in Cambridge, MA, received approval for emergency use in the U.S. on December 18Trusted Source. In a phase 3 trial, 30,000 volunteers received either a placebo or two doses of the vaccine, 28 days apart. The results indicated that the vaccine was 94% effective.
Other vaccines that have approval for use in various countries include:
- The Oxford AstraZeneca vaccine, in the United Kingdom
- Coronavac, developed by Sinovac, in China
- The Sputnik V vaccine, in Russia
- Covaxin, developed by Bharat Biotech, in India
Meanwhile, the Novavax vaccine is currently undergoing Trusted Source phase 3 trials, as is Janssen’s COVID-19 vaccine. Both were developed by companies based in the U.S.
A person can keep up to date with the latest vaccine developments in the country using the Regulatory Affairs Professionals Society’s COVID-19 vaccine tracker.
Are the vaccines safe?
A vaccine needs to pass through several stages of trials before the manufacturer can apply for approval from a country’s health authority. In the U.S., the FDA gives this approval, and the Centers for Disease Control and Prevention (CDC)Trusted Source also work to ensure public safety.
Vaccine trials involve ever-larger numbers of people. The last stage, phase 3, includes tens of thousands of participants.
At first, the specific long-term effects of any new medical treatment, including a vaccine, are unknown. The key is to balance the potential risks of getting a vaccine that has undergone extensive testing with the known dangers of developing COVID-19.
In the short term, a person who has had a COVID-19 vaccine may experience flu-like symptoms and other side effects, including:
- pain at the injection site
- swelling at the injection site
- headache and muscle pain
- a fever
The side effects may be worse after the second dose of the vaccine because the body’s immune response will be intensified.
The CDC encourage people to use a smartphone-based health checker called V-safeTrusted Source to inform the authorities about any side effects. This helps them monitor the impact of the vaccine and do ongoing work to ensure public safety.
It is essential to receive the vaccine from a licensed healthcare professional and follow every instruction, including getting a second dose. A person may get the vaccine at a local health department, hospital, clinic, or pharmacy.
Getting the vaccine
Vaccine doses are currently limited. For this reason, the first to receive the vaccine will be healthcare workers, residents of long-term care facilities, first responders, and people aged 75 years and olderTrusted Source. As more doses become available, everyone will be able to receive it.
A person may need to pay an administrative feeTrusted Source for the vaccine. Insurance companies will reimburse this, and people without insurance can seek reimbursement from the Department of Health and Human Services’ Provider Relief Fund. Otherwise, the vaccine is free.
To learn when the vaccine becomes available, check with local and state health departments regularly. The CDC provide a directory hereTrusted Source.
Types of COVID-19 vaccine
Researchers have used various approaches to developing vaccines that protect against COVID-19. As a result, they have developed different types of vaccine, including:
- whole virus vaccines
- recombinant protein subunit vaccines
- replication-incompetent vector vaccines
- nucleic acid vaccines
We explore these types in more detail below:
Whole virus vaccine
Also known as an “inactivated” or “weakened” virus vaccine, this type contains dead or inactivated forms of the virus.
These vaccines cannot cause an infection because they do not contain the live virus.
The COVID-19 vaccines made by Sinovac, Bharat Biotec, and the Wuhan Institute of Biological Products are of this type.
Recombinant protein subunit vaccine
This type of vaccine triggers a strong immune response to a key part of the virus. It cannot cause an infection because it does not contain a live pathogen, such as a virus.
Researchers are investigating whether they can make a recombinant protein subunit vaccine that targets a proteinTrusted Source, called the spike protein, that the new coronavirus uses to latch onto and infect cells.
Novavax is one company taking this approach, using nanoparticle technology.
Replication-incompetent vector vaccine
This type acts as a platform for carrying genes that the body can express to provide immunity.
The AstraZeneca vaccine, which has approval in some countries, is a replication-incompetent vector vaccine. It usesTrusted Source a harmless, weakened adenovirus that causes the common cold in chimpanzees to provoke an immune response.
The scientists then changed the virus to make it suitable for use in humans. In other vaccines, this type of virus has safely produced a strong immune response.
In July 2020, an Ebola vaccine of this type received approval, and it may provide the basis for further COVID-19 vaccines.
Nucleic acid vaccine
This type is also called an mRNA-based vaccine. Vaccination involves injecting genetic material called mRNA into live host cells.
Each of these vaccines is designed to target a particular pathogen. In a COVID-19 vaccine, the mRNA contains instructions for producing coronavirus spike protein. The vaccine presents this information to the immune system, and as a result, the body produces antibodies to combat the virus.
Pfizer, BioNTech, and Moderna have developed this type of vaccine. The Pfizer-BioNTech and Moderna vaccines are already available in the U.S.
How do vaccines work?
Vaccines prompt Trusted Source the immune system to make antibodies to defend against specific diseases. In other words — they make the immune system behave as if the body already had this illness.
Vaccines achieve this without making the person sick.
After vaccination, the person develops immunity to the disease. Their body can fight off the infection if exposure to the pathogen, such as the novel coronavirus, occurs.
An effective vaccine stimulates the immune system without kicking it into overdrive. Developing a vaccine that works without causing unwanted side effects is the goal for researchers.
Vaccines also need to be safe for everyone, including people with allergies, young children, people who are pregnant or breastfeeding, older adults, and people with underlying health conditions.
While waiting for a vaccine, people need to take other steps to protect themselves and others from COVID-19.
The CDC recommend the followingTrusted Source ways of reducing the risk of infection:
- wearing a face covering in public
- washing the hands with soap and hot water frequently, for at least 20 seconds at a time
- using a hand sanitizer, with at least 60% alcohol, when washing the hands is not possible
- covering any sneeze or cough with a tissue, disposing of this at once, and washing the hands
- avoiding touching the face
- regularly cleaning and disinfecting surfaces that people frequently touch, such as doorknobs
- limiting or avoiding handshakes
- staying home and away from others if sick
- staying at least 6 feet away from people who are not housemates
- avoiding crowds whenever possible
- avoiding poorly ventilated places whenever possible
- being watchful for any symptoms, including a high fever and a cough
If a person has a mild or asymptomatic form of COVID-19, it is still crucial to limit contactTrusted Source with others, especially older adults and people with weakened immune systems.
Read more about how to prevent COVID-19 here.
If anyone needs medical care for what may be COVID-19 symptoms, call ahead to let the clinic or hospital know about the problem and wear a face mask on the way.
The CDC also recommend that anyone who may have been exposed to the virus:
- contacts a healthcare provider
- keeps track of their symptoms
- isolates at home, staying away from others as much as possible
- seeks emergency medical care for any severe symptoms, such as difficulty breathing
Some common COVID-19 symptoms include:
- a fever
- a persistent cough
- a loss or change in sense of smell or taste
Learn about the early symptoms here.
Maintaining a balanced diet, staying active, and making other healthful choices can also help.
There is no evidence that home or alternative remedies can help prevent COVID-19. Here, learn about these and other coronavirus myths.