The CDC COVID-19 Science Update provides peer-reviewed and preprint research on the virus and its variants. A mathematical model shows that even with high vaccine efficacy, the reproduction number (R) remains above 1, leading to potential deaths. Vaccination combined with lifting non-pharmaceutical interventions (NPIs) is needed to prevent future waves. A study found that mRNA vaccines reduce asymptomatic infection risk by 65% and 80% after two doses. The ChAdOx1 nCoV-19 vaccine showed low efficacy against the B.1.351 variant, suggesting the need for boosters. The B.1.1.7 variant is more transmissible and associated with higher mortality. A study found that B.1.1.7 increases mortality risk by 60-70% compared to other variants. A new variant, N.9, with the E484K mutation, is spreading in Brazil and may reduce vaccine effectiveness. A Danish study found 78.8% protection against reinfection, with higher protection for younger individuals. A study on household transmission found that children are less likely to spread the virus. A study on healthcare workers showed that two vaccine doses or natural infection provide strong protection. A study on SARS-CoV-2 antigen tests found that temperature affects their performance. Socioeconomic factors mediate racial disparities in COVID-19 outcomes. Long-term immunity is present in hospitalized patients. Multiple variants, including B.1.1.7, have mutations that increase transmissibility. mRNA vaccines show reduced neutralizing activity against B.1.1.7 with the E484K mutation. Clear masks improve communication during surgical procedures. Vaccination does not worsen long COVID symptoms. Maternal antibodies are transferred to fetuses after mRNA vaccination. The CDC emphasizes that the Science Update is for informational purposes and does not represent official views.The CDC COVID-19 Science Update provides peer-reviewed and preprint research on the virus and its variants. A mathematical model shows that even with high vaccine efficacy, the reproduction number (R) remains above 1, leading to potential deaths. Vaccination combined with lifting non-pharmaceutical interventions (NPIs) is needed to prevent future waves. A study found that mRNA vaccines reduce asymptomatic infection risk by 65% and 80% after two doses. The ChAdOx1 nCoV-19 vaccine showed low efficacy against the B.1.351 variant, suggesting the need for boosters. The B.1.1.7 variant is more transmissible and associated with higher mortality. A study found that B.1.1.7 increases mortality risk by 60-70% compared to other variants. A new variant, N.9, with the E484K mutation, is spreading in Brazil and may reduce vaccine effectiveness. A Danish study found 78.8% protection against reinfection, with higher protection for younger individuals. A study on household transmission found that children are less likely to spread the virus. A study on healthcare workers showed that two vaccine doses or natural infection provide strong protection. A study on SARS-CoV-2 antigen tests found that temperature affects their performance. Socioeconomic factors mediate racial disparities in COVID-19 outcomes. Long-term immunity is present in hospitalized patients. Multiple variants, including B.1.1.7, have mutations that increase transmissibility. mRNA vaccines show reduced neutralizing activity against B.1.1.7 with the E484K mutation. Clear masks improve communication during surgical procedures. Vaccination does not worsen long COVID symptoms. Maternal antibodies are transferred to fetuses after mRNA vaccination. The CDC emphasizes that the Science Update is for informational purposes and does not represent official views.