Fact or Fiction

Debunking common misconceptions about the COVID-19 vaccine in our Fact or Fiction video series.


The vaccine takes time to begin working. It can take around two weeks after each shot for the vaccine to be fully effective. Also, after you’ve been vaccinated you may still catch COVID and have mild symptoms. Because you can still carry the virus, (even if it doesn’t make you visibly sick) it’s important to wear a mask and maintain social distancing to make sure you do not pass the virus to others who are not yet vaccinated. The combination of getting vaccinated and following CDC’s recommendations to protect yourself and others will offer the best protection from COVID-19.


Short-term side effects are similar to other symptoms you may experience after a vaccination and include fever, chills, headache, fatigue, joint and muscle aches, as well as pain at the injection site. These symptoms are common and can range from mild to severe and may occur after the first or second dose of the vaccine. People who receive the vaccine should plan ahead to accommodate expected side effects.

COVID-19 vaccines are still being tested for long-term side effects. To date, no long-term safety issues have been detected. For any vaccine, most side effects are reported within the first six (6) weeks.

Scientists at the Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) continue to monitor the vaccines’ safety, provide information to the public, and take action on any safety concerns if they arise. In addition, Beth Israel Lahey Health is participating in a panel of leading infectious diseases physicians from academic centers across Massachusetts to review the data used by the FDA for each vaccine authorized under Emergency Use Authorization (EUA) to provide an expert and unbiased evaluation of vaccine safety and efficacy.

Your doctor can help answer questions about your personal risks, but here’s what we know for sure: Getting sick with COVID-19 is dangerous. COVID-19 can cause long-term health problems in some people, even in mild cases. It’s unlikely that vaccine-related side effects that are riskier than contracting COVID-19 will emerge.


None of the vaccines contain a live COVID-19 virus. The goal of vaccination is to teach the body’s immune system how to recognize and fight the virus that causes COVID-19. Sometimes this process can cause symptoms, such as fever, but these symptoms are normal and are actually a good sign that the body is building immunity.

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 or another virus just before or just after vaccination and get sick.