The CDC issues new guidance for distributing booster shots for adults that have already received their initial COVID-19 vaccine. Individuals that are 65 years of age or older and living in a long term care facility and adults with certain pre-existing health conditions are eligible for a booster shot. An ongoing study related to COVID-19 vaccines by the World Health Organization is looking at the safety and effectiveness of mixing vaccines by various manufacturers. For more on this, here's Matthew Davis.