How are these different from the other two recommendations?
Adults 18–49 who have underlying medical conditions are at increased risk for severe illness from COVID- 19, as are people 18-64 are in an occupational or institutional setting where the burden of COVID-19 infection and risk of transmission are high. However, that risk is likely not as high as it would be for adults 50 years and older who have underlying medical conditions, or people who live in long-term care settings. With the lower risk, the data do not support that everyone who falls into this group should get a booster
shot. Therefore, CDC’s recommendation is not as strong for these populations, but still allows a booster shot to be available for those who would like to get one. People 18 and older who are at high risk for severe COVID-19 due to underlying medical conditions or their occupation should consider their individual risks and benefits when making the decision of whether to get a booster shot. This recommendation may change in the future as more data become available.