Vaccine Effectiveness FAQ


I am nervous about getting the vaccine. Why should I get it?

It is normal to feel uneasy or unsure about getting a new vaccine. But the benefits of getting the COVID-19 vaccine and helping to end the pandemic far outweigh the risks.

  • Worry less: Vaccines are highly protective in preventing severe disease and hospitalization. The vaccines are effective against mild disease with protection ranging from 66-95% depending on the type of vaccine received. You will be helping to protect others around you, both young and old.
  • You will be helping to protect others around you, both young and old.
  • We need about 50% to 80% of the community to get the vaccine in order for it to be effective.

We are all in this together, and for every person that gets the vaccine, we are one step closer to ending the pandemic.

Do I need to continue wearing my mask after I receive the vaccine?

To reduce the risk of breakthrough infection and the possibility of spreading it to others, the CDC recommends those fully vaccinated and in areas of substantial to high transmission rates to continue wearing masks while indoors. Learn about the level of transmission in your county.

In areas of low to moderate transmission, fully vaccinated people can resume activities without wearing a mask or physically distancing, except where required by federal, state, local, tribal, or territorial laws, rules, and regulations, including local business and workplace guidance.

You will still be required to wear a mask in health care settings and on planes, buses, trains, and other forms of public transportation traveling into, within, or out of the United States, and in U.S. transportation hubs such as airports and stations.

Dartmouth-Hitchcock will continue to require mask use at all times in all facilities, without regard to vaccination status. Our policy will continue to apply to all D-H staff, patients, visitors, and any others entering our facilities.

View the full list of CDC recommendations for vaccinated individuals.

According to the CDC, fully vaccinated people can:

  • Resume activities without wearing masks or physically distancing, except where required by federal, state, local, tribal, or territorial laws, rules and regulations, including local business and workplace guidance
  • Resume domestic travel and refrain from testing before or after travel or self-quarantine after travel
  • Refrain from testing before leaving the United States for international travel (unless required by the destination) and refrain from self-quarantine after arriving back in the United States
  • Refrain from testing following a known exposure, if asymptomatic, with some exceptions for specific settings
  • Refrain from quarantine following a known exposure if asymptomatic
  • Refrain from routine screening testing if feasible

Businesses and organizations may continue to require masks in order to keep their customers and employees safe. You should follow the rules established by those entities. In addition, many people have become used to to wearing masks and will choose to continue to ‘mask up’ to keep themselves, and others, safe. Remember that none of the vaccines are 100% protective and there are still large segments of our populations that have not achieved immunity. It is reasonable to choose to continue to wear a mask, even if you are vaccinated.

How effective is the vaccine, and when does the vaccine protection begin?

Based on manufacturer data, Pfizer-BioNTech’s vaccine was found to be 94.6% effective against COVID-19 beginning 7 days after the second dose. Moderna's vaccine was found to be 94.1% effective against COVID-19 after receiving two doses and 100% effective against severe COVID-19 disease. Janssen's vaccine was found to be 66.3% effective against symptomatic COVID-19 and 93.1% effective in preventing hospitalizations at 14 days after vaccination. Additional information about effectiveness can be found on the vaccine fact sheets:

Could I test positive for COVID-19 after receiving the vaccine?

No, not as a result of the vaccine alone. The vaccines won't cause you to test positive on viral tests. If your body develops an immune response, which is the goal of vaccination, there is a possibility you may test positive on some antibody tests.

Will there be a test for immunity as a result of the vaccine?

No, testing for immunity is not recommended. There are two antibody tests currently in use nationally. One test will generally only detect the type of antibody that is produced by natural infection, not antibodies produced by a response to vaccination. The other test is unable to distinguish between antibodies produced by the vaccine or by natural infection. Given the experience with the COVID-19 vaccine so far, experts are confident in the protection provided even if you experience little to no side effects from the vaccine.

Is it better to get natural immunity to COVID-19 rather than immunity from a vaccine?

No. While having the COVID-19 infection does give some immunity, it is a dangerous option, causing serious illness in many, with debilitating symptoms that can last for months. And it kills at least 1-2% of those who get it. Also, experts think immunity from the disease itself may not be long-lasting. Vaccination is the best protection; it is very safe and provides the best immunity.