People with certain health conditions that make them moderately or severely immunocompromised may get a fourth mRNA Covid-19 shot, according to updated guidelines from the US Centers for Disease Control and Prevention.
The CDC authorized a third dose for certain immunocompromised people 18 and older in August. It said a third dose, rather than a booster -- the CDC makes a distinction between the two -- was necessary because the immunocompromised may not have had a complete immune response from the first two doses.
A study from Johns Hopkins University this summer showed that vaccinated immunocompromised people were 485 times more likely to end up in the hospital or die from Covid-19 compared to most vaccinated people. In small studies, the CDC said, fully vaccinated immunocompromised people accounted for about 44% of the breakthrough cases that required hospitalization. People who are immunocompromised are also more likely to transmit the virus to people who had close contact with them.
The US Food and Drug Administration has also authorized booster shots of all three available vaccines for certain people and that would include the immune compromised, the CDC says.
Research showed that a booster dose enhanced the antibody response to the vaccine in certain immunocompromised people.
That would make for a fourth shot at least six months after completing the third mRNA vaccine dose. At this time, the CDC does not have a recommendation about the fourth shot. People should talk to their doctors to determine if it is necessary, the CDC says.
Moderately to severely immunocompromised people include those who are in active cancer treatment for cancers of the blood or for tumors, certain organ transplant and stem cell recipients, people with advanced or untreated HIV, and those who take a high-dose corticosteroids or other drugs that may suppress their immune systems. The CDC estimates about 9 million people who live in the US, or about 2% of the population, fall into this category.
People who are immunocompromised who got the single-dose Johnson & Johnson shot should get a booster at least two months after their initial vaccine. People who choose a Moderna vaccine as a booster, even if they received a different vaccine as the first dose, should get the half-dose sized shot that was authorized as a booster for Moderna's vaccine, the CDC said.
Even if they are vaccinated, the CDC recommends people with conditions that compromise their immune systems should still try to avoid crowds and poorly ventilated spaces, and should wear a mask in indoor public spaces.
History of vaccine mandates in the US
History of vaccine mandates in the US
1777: George Washington mandates smallpox vaccines for all his soldiers
1809: Massachusetts institutes the first vaccine mandate
1813: Congress establishes the US Vaccine Agency
1855: Massachusetts institutes the first school vaccine mandates
1867: The Urbana, Ohio, board of health passes a law requiring citizens to get available vaccines in the event of future epidemics
1898: The UK’s Vaccination Act allows objections and exemptions to vaccine mandates
1902: Congress passes the Biologics Control Act
1905: The US Supreme Court decides Jacobson v. Massachusetts
1922: The US Supreme Court decides Zucht v. King
1944: The US Supreme Court decides Prince v. Massachusetts
1977: The nationwide Childhood Immunization Initiative begins
1980: All 50 states have laws requiring vaccines for children to attend public schools
1987: The Arizona Court of Appeals decides Maricopa County Health Department v. Harmon
2015: California becomes the first state to eliminate personal belief exemptions to vaccines for children in public and private schools
2021: President Biden announces a sweeping COVID-19 vaccine mandate
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