After your final COVID-19 vaccine dose, it takes about two weeks for your body to build up protection. After those two weeks, you have good protection against illness for yourself. However, we’re still learning how vaccines will affect the spread of COVID-19.
Though the vaccines work very well, they do not work 100% of the time. There is a small chance that fully vaccinated people could still get COVID-19. It is important to continue to follow all public health guidance to reduce the spread of COVID-19 even after you have been fully vaccinated.
Continue to wear a mask that fits well and stay at least 6 feet away from other people whenever you are:
Visiting with unvaccinated people from multiple households.
Wash your hands often.
Stay home if you are sick, especially if you have been around someone who has COVID-19. If you have symptoms of COVID-19, you should get tested. Learn more at CDC: Symptoms of Coronavirus.
Do not visit people who have had close contact to someone with COVID-19 and are in quarantine.
Avoid crowds and poorly-ventilated spaces.
If you travel, follow CDC requirements and recommendations: Domestic Travel During COVID-19.
Follow guidance specific to your workplace.
At this time, we do not know if this will be a vaccine that people need to get again, like needing a tetanus shot every 10 years or getting a flu shot every year.
The COVID-19 vaccine cannot give you COVID-19 disease. The vaccine does not provide instant and complete protection. It takes about two weeks after getting fully vaccinated for your body to build up protection from COVID-19 disease. You could be exposed during this time. Although your protection is pretty good after those two weeks, there is still a small chance you could become infected with COVID-19 and develop symptoms. If you do get sick, it is likely that your symptoms will be milder than if you didn't get vaccinated.
While the available vaccines have been shown to be very effective at preventing COVID-19 illness in those who are vaccinated, we are still learning to what degree the vaccine may prevent someone who is vaccinated from passing along the virus to other people. Someone who is vaccinated might be exposed to COVID-19 but have no symptoms. We do not know if that person could still spread COVID-19 to others and not know it. We are also still learning how long protection from the vaccine lasts.
This is why it is important for everyone, whether vaccinated or not, to continue to follow other public health recommendations to prevent the spread of COVID-19: wear a mask, stay 6 feet from others, wash your hands often, and stay home if sick.
We will continue to evaluate these recommendations as more people in the community get vaccinated and we see how this impacts spread of disease.
Some side effects are common after vaccination. They are a result of your body responding to the vaccine (it's also OK if you don't have any side effects at all). Common side effects from the vaccine can include pain, swelling, or redness where the shot was given, and sometimes feeling achy and tired. Some people may have a headache or fever. Side effects happen within a day or two of vaccination and go away one to two days later.
Some side effects can be the same or similar as symptoms of COVID-19 or other illnesses. The COVID-19 vaccine cannot give you COVID-19 disease. For example, these symptoms after vaccination could be from the vaccine or other illness:
Other symptoms are less likely to be side effects of the vaccine but are signs of possible illness. If you have any of the below symptoms, or if you have worsening symptoms, you should get tested for COVID-19 and other illnesses as recommended by your health care provider:
Loss of taste or smell
Shortness of breath
Nasal congestion, or stuffy or runny nose
Serious adverse events
A serious adverse event is something that results in hospitalization or is life-threatening. Most adverse effects occur in the six weeks after getting a vaccine.
If you have a severe reaction, contact your health care provider. If it is an emergency, go to a hospital or call 911.
A few people who have received the Johnson & Johnson COVID-19 vaccine have developed blood clots involving blood vessels in the brain, abdomen, and legs along with low levels of platelets (blood cells that help your body stop bleeding). Most people who developed these blood clots and low levels of platelets were adult women younger than 50 years old. The chance of having this occur is very rare. For women 50 years and older and men of all ages, this adverse event is even more rare. This condition is treatable. For three weeks after receiving the Johnson & Johnson COVID-19 vaccine, be on the lookout for these symptoms:
Shortness of breath
Abdominal/stomach pain that doesn't go away
Severe headaches or headaches that won't go away
Easy bruising or tiny blood spots under the skin beyond the site of the injection
If you have any of these symptoms after getting the vaccine, you should seek medical attention right away. Tell the health care provider that you recently received the Johnson & Johnson vaccine.
Three weeks after vaccination, the risk of developing a blood clot is very low.