The Centers for Disease Control and Prevention reported that as of April 29, 60% of the entire United States population has been infected with COVID-19. What does this mean in terms of immunity?

Immunity levels vary: There is not one answer when it comes to COVID-19 immunity. The length and strength of immunity from the virus depends on many different factors, such as vaccination status and individual health levels.

  • “Some people develop more antibodies after an infection than others. It’s also not clear exactly how antibody levels correlate with protection against infection, so a positive antibody test doesn’t necessarily mean you’re immune to the virus,” Dr. Kristie Clarke, co-lead for the CDC’s COVID-19 Epidemiology and Surveillance Taskforce Seroprevalence Team, told Time magazine.

For those who haven’t been vaccinated: Johns Hopkins Medicine states that those who are not vaccinated are more than two times as likely to be infected with COVID-19, as opposed to those who have been vaccinated, even after they had been recently infected with COVID-19.

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  • There is no long-term study that can give a definite answer, but the CDC recommends that those who aren’t up to date on vaccinations should quarantine for at least five days after exposure to someone with COVID-19, even if they have already been infected.
  • The University of South Carolina reported that even people who have been infected with COVID-19 should get vaccinated to ensure the best protection against the virus.
  • Bruce Farber, chief of infectious diseases at Northwell Health in New York, told Time magazine that it would be “‘very unusual’ to get COVID-19 within 90 days of a previous case.”

For those who are fully vaccinated: The CDC states that people who have had a confirmed case of COVID-19 in the last 90 days and are fully vaccinated do not need to quarantine if they’ve come into contact with someone who has tested positive for COVID-19.

  • A study in the New England Journal of Medicine states that “hybrid immunity” — immunity from a COVID-19 infection, along with full vaccination and booster status — can last up to one year.
  • Although vaccinations have been shown to reduce chances of COVID-19 infection, a study published in the Lancet states that vaccine effectiveness waned by about 20-30% within six months.

Children have longer immunity: Time magazine cited a study that found that more children than adults carried antibodies six months after infection.