It is normal for virus-fighting antibodies—such as those that are stimulated by a COVID-19 vaccine—to wane over time. Monitoring antibody levels in the blood is one way to measure vaccine efficacy and research has found that protection remains high for six months after the second shot of a Pfizer or Moderna vaccine.Mar 30, 2022
Antibodies able to block the omicron coronavirus variant last four months after a third dose of Pfizer-BioNTech's vaccine, according to a study published Jan. 22 by bioRxiv.Jan 25, 2022
Quarantine: If you have received all vaccine and booster doses recommended by CDC, you do not need to quarantine. You should wear a well-fitting mask around others for 10 days from the date of your last close contact with someone with COVID-19 (the date of last close contact is considered day 0).
Most people who get COVID-19 are unvaccinated. However, since vaccines are not 100% effective at preventing infection, some people who are fully vaccinated will still get COVID-19. An infection of a fully vaccinated person is referred to as a “breakthrough infection.”
At this time, it is unknown for how long antibodies persist following infection and if the presence of antibodies confers protective immunity.Jan 31, 2022
Vaccines work by stimulating your immune system to produce antibodies, exactly like it would if you were exposed to the disease. After getting vaccinated, you develop immunity to that disease, without having to get the disease first.
People who are up to date with their vaccine should still monitor for symptoms of COVID-19 for 10 days after being around someone with COVID-19. You should also wear a well-fitting mask in public indoor settings and monitor for symptoms for 10 days. Do not go to places where you are unable to wear a mask.
People who have tested positive for COVID-19 within the past 3 months and recovered do not have to quarantine or get tested again as long as they do not develop new symptoms.
If you come into close contact with someone with COVID-19, you should quarantine if you are not up to date on COVID-19 vaccines. This includes people who are not vaccinated.
Because vaccines are not 100% effective, as the number of people who are fully vaccinated goes up, the number of vaccine breakthrough infections will also increase. However, the risk of infection remains much higher for unvaccinated than vaccinated people.
COVID 19-vaccines are effective and can lower your risk of getting and spreading the virus that causes COVID-19. COVID-19 vaccines also help prevent serious illness and death in children and adults even if they do get COVID-19.
See full answerRecent data[1 MB, 68 pages] suggest COVID-19 vaccines become less effective at preventing infection or severe illness over time, especially for people ages 65 years and older. This is why booster shots are recommended for people ages 12 years and older who have completed their primary vaccination series. However, even as the vaccine's ability to prevent infection decreases with time, COVID-19 vaccination continues to reduce the risk of hospitalization and death when people become infected with COVID-19. People who have certain medical conditions or who are taking medications that weaken their immune system may not be completely protected even if they completed the primary vaccination series.