For individuals who previously received a Johnson & Johnson COVID-19 vaccine, data reveal that mRNA vaccines provide the most effective and safe protection against infection with the virus that causes COVID-19 and severe illness. A new CDC report shows that adults who received the Johnson & Johnson COVID-19 vaccine as both their primary dose and booster dose had lower levels of protection against COVID-19-associated emergency department and urgent care visits during Omicron compared to those who received an mRNA booster dose. CDC has recommended a second booster dose for people who received both a primary dose and a booster dose of the Johnson & Johnson vaccine at least 4 months ago.