Feb 23, 2021 2:00 PM

Getting vaccinated for COVID-19 is a big step toward protecting yourself, your family, and your friends from the virus that causes this potentially deadly disease. In the larger picture, vaccinations will get us that much closer to corralling COVID-19 nationwide. In fact, as more of the population gets the COVID-19 vaccine, we will be closer to getting back to our normal, everyday lives.

But we may still have a long way to go before we can change our behaviors in public and shop, socialize, and travel without using face masks and practicing social distancing, says Hannah Imlay, MD, assistant professor in the Division of Infectious Disease at University of Utah Health. Here are a few reasons why.

COVID-19 vaccines are highly effective

The three vaccines that are currently available in the U.S.—Moderna, Pfizer-BioNTech and Johonson & Johnson—each give substantial protection against severe illness from COVID-19. They cannot guarantee complete immunity for every person, but large clinical trials showed that the vaccines nearly prevent hospitalization and death from COVID-19.

It takes time to reach full protection

Vaccines don’t provide immediate protection against COVID-19. Our bodies need time to develop immunity to the virus. The Johnson & Johnson vaccine is a single-dose vaccine. Studies show that this vaccine offers some protection two weeks after vaccination and achieves maximal protection after four weeks. The Moderna and Pfizer-BioNTech vaccines require two doses and it takes two weeks after the second dose to be protected. With that in mind, be aware that it’s still possible to get infected in the time until immunity develops.

COVID-19 booster shots are also recommended following your primary vaccine series. A booster dose is recommended two months after the first dose of the J&J vaccine (Pfizer-BioNTech or Moderna are preferred), five months after the second dose of the Pfizer-BioNTech vaccine, and six months after the second dose of the Moderna vaccine. A booster shot provides additional protection from emerging virus variants of COVID-19.

Vaccines and viral spread

Even though COVID-19 vaccines are very effective at preventing you from getting sick, we don’t yet know how well they prevent you from spreading the virus to others. A person’s interactions can have ripple effects and this could be of concern if the virus is spread to unvaccinated people at high risk for becoming seriously ill with COVID-19. Imlay says gathering in large groups during high community spread is not in line with the goal of decreasing community transmission. “We think the risk of asymptomatic transmission is less if you are vaccinated, but we don’t know how much, and that’s based on a small amount of data,” Imlay says. Until we get more data, it’s important to continue using all the tools available to protect others who might be at risk for becoming hospitalized or dying from COVID-19.

The journey to herd immunity

This threshold, called “herd immunity,” means it is extremely difficult for the virus to spread from person to person. Scientists project that 75 to 80 percent of us will need to be vaccinated before that can happen. Until then, it will be important to keep masking up, physically distancing, and avoiding crowds.

The variant variable

Like all viruses, the virus that causes COVID-19, called SARS-CoV-2, mutates. Since the original virus, more variants have acquired changes that allow the virus to spread more easily. The COVID-19 vaccines authorized for use in the U.S. still offer protection against these variants. However, the longer the pandemic lasts, the more likely it is for more variants to arise. It is possible that our current vaccines may not work as well against future variants. Luckily, new technology means it is relatively easy and fast to create new vaccines. It could be that similar to an annual flu shot, we may need an annual COVID-19 vaccine booster to protect against additional variants.

One weapon in the fight against COVID-19

Imlay describes vaccination as a public health intervention—and another tool in helping control the pandemic. “It’s helpful to think of each particular health measure (masking, physical distancing, hand washing, avoiding crowds) as a tool to help with COVID-19 transmission,” Imlay says. “Layering these together, they add up to be very effective.” If people continue to use these tools and get vaccinated, the number of COVID-19 cases will decrease. When community transmission slows and the population becomes healthier, interventions can be peeled back.


This information was accurate at the time of publication on December 1, 2021. Due to the changing nature of the COVID-19 pandemic, some information may have changed since the original publication date. 

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