The COVID-19 vaccine does not prevent a person from contracting SARS-CoV-2, the virus that causes the disease. However, it does help protect against serious illness, hospitalization, and death. It also helps reduce the spread of SARS-CoV-2.

This article addresses whether the COVID-19 vaccine offers full protection against the disease. It also provides information on how the vaccine protects people and how long the effects last. Finally, it advises on how to get the vaccine and offers some additional tips for prevention against COVID-19.

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The COVID-19 vaccine does not prevent COVID-19. A person who is fully vaccinated can still contract the SARS-CoV-2 virus, which causes COVID-19, and may go on to develop the disease.

However, a 2021 science brief from the Centers for Disease Control and Prevention (CDC) outlines recent scientific evidence demonstrating the benefits of the COVID-19 vaccine. These include reducing rates of SARS-CoV-2 infection and transmission and reducing the risk of severe disease, hospitalization, and death.

A person’s susceptibility to COVID-19 following full vaccination may depend on the variant of SARS-CoV-2 they have exposure to.

At present, the most prevalent variant of SARS-CoV-2 in the United States is the Omicron variant.

A person who develops an Omicron infection can still spread the virus to others if they have received the vaccine. However, the risk of this variant causing severe symptoms and complications is reduced in someone who is fully vaccinated compared with a person who is not.

Viral antigens are molecular structures that sit on the surface of viruses. Each virus has its own specific viral antigens. When a person contracts a virus, their immune system makes antibodies that bind to and destroy the viral antigens.

Vaccines work by conditioning the immune system to produce virus-specific antibodies without making the person sick. They do this by exposing the body to the inactive parts of a virus that trigger an immune response.

This teaches the immune system how to fight the virus by making virus-specific antibodies. Therefore, if someone goes on to contract the virus, their body is able to respond more effectively.

Different types of vaccine condition the immune system in different ways. Some examples are below.

  • Weakened or inactive vaccines: These vaccine types use a weak or inactive form of the virus to generate an immune response without causing the person to become ill.
  • Viral vector vaccines: These vaccines use a modified version of a harmless virus to produce coronavirus proteins. Exposure to these proteins triggers the immune system to produce SARS-CoV-2 antibodies. For example, the AstraZeneca vaccine uses a virus that would normally cause a cold in chimpanzees but not humans, making it safe for human use.
  • Protein-based vaccines: These vaccines use sections of coronavirus proteins to mimic the SARS-CoV-2 virus. Examples include Nuvaxovid or NVX-CoV2373.
  • DNA and RNA vaccines: These vaccines use genetically modified DNA or RNA to produce proteins that trigger an appropriate immune response. Examples include the Pfizer vaccine, which is an RNA vaccine, and the Moderna vaccine, which is an mRNA vaccine.

The COVID-19 vaccine does not guarantee protection for everyone who takes it. However, it does reduce the risk of contracting the virus and helps protect against severe COVID-19 symptoms and complications.

Despite continual research, it remains unclear exactly how long the COVID-19 vaccines provide protection from the disease. However, the World Health Organization (WHO) states that the vaccine appears to provide strong protection against serious illness and death for at least 6 months.

To increase a person’s protection, booster doses are available every 4–6 months after a person receives their initial two doses of the vaccine.

Protection from the vaccine is likely to fade more quickly in people who:

  • are older
  • have underlying health conditions
  • have greater exposure to the virus

The WHO also recommends that people take the following precautionary measures to maximize their protection against COVID-19:

Several different vaccines currently have WHO approval. Examples include the:

  • Pfizer/BioNTech Comirnaty vaccine
  • SII/COVISHIELD and AstraZeneca/AZD1222 vaccines
  • Janssen/Ad26.COV 2.S Johnson & Johnson vaccine
  • Moderna COVID-19 vaccine, or mRNA 1273
  • Sinopharm COVID-19 vaccine
  • Sinovac-CoronaVac vaccine
  • Bharat Biotech BBV152 COVAXIN vaccine
  • Covovax (NVX-CoV2373) vaccine
  • Nuvaxovid (NVX-CoV2373) vaccine

Vaccines with WHO approval help provide protection against all variants of the SARS-CoV-2 virus.

In the U.S., a person can get the COVID-19 vaccine by going to a COVID-19 vaccination location. The CDC offers the following advice on finding a location:

  • searching online, using vaccines.gov
  • texting the local zip code to the number 438829
  • calling the number 1-800-232-0233

Additionally, a person can:

  • speak to a healthcare professional
  • contact their state healthcare provider
  • check with a local pharmacy

Most people are eligible to receive the COVID-19 vaccine. However, the following people should check with a doctor beforehand:

  • people with a history of allergy to the vaccine
  • anyone with a fever over 38.5ºC (101.3ºF) on the day of the vaccination
  • anyone who has tested positive for the virus on the day of the vaccination

Besides receiving the full course of vaccinations against COVID-19, other steps a person can take to help prevent the spread of the SARS-CoV-2 virus include:

  • continuing with physical distancing measures, such as avoiding nonessential travel and minimizing contact with others
  • maintaining personal hygiene
  • washing the hands thoroughly and regularly
  • frequently applying strong, alcohol-based hand sanitizers
  • disinfecting surfaces
  • keeping rooms well ventilated

Isolation is no longer necessary in most countries. However, a person who has an upcoming surgery or medical appointment may consider going into quarantine the week beforehand to minimize their chances of contracting the virus.

The rollout of the COVID-19 vaccine has helped reduce rates of infection with the SARS-CoV-2 virus, which causes the disease. While the vaccine does not provide complete protection against COVID-19, it helps reduce the severity of its symptoms. Researchers have associated the vaccine with an overall decrease in hospitalizations and deaths.

The COVID-19 vaccine has also helped reduce transmission of the SARS-CoV-2 virus, meaning fewer people are contracting the infection. Other ways to help prevent transmission include washing the hands thoroughly and regularly, continuing to physically distance, and wearing a face mask in public.

Scientists are still unsure how long the COVID-19 vaccine will remain effective in a person’s body. Strong protection is likely to last for at least 6 months, after which a person can receive booster vaccines every 4–6 months to top up their protection.