CNN – “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…” [h/t Pete Weiss]