As of October 28, 2022, a total of 28,244* monkeypox (mpox) cases have been reported in the United States during an outbreak that has disproportionately affected gay, bisexual, and other men who have sex with men (MSM) (1). JYNNEOS vaccine (Modified Vaccinia Ankara vaccine, Bavarian Nordic), administered subcutaneously as a 2-dose (0.5 mL per dose) series (with doses administered 4 weeks apart), was approved by the Food and Drug Administration (FDA) in 2019 to prevent smallpox and mpox disease (2); an FDA Emergency Use Authorization issued on August 9, 2022, authorized intradermal administration of 0.1 mL per dose, increasing the number of persons who could be vaccinated with the available vaccine supply(†) (3). A previous comparison of mpox incidence during July 31-September 3, 2022, among unvaccinated, but vaccine-eligible men aged 18-49 years and those who had received ≥1 JYNNEOS vaccine dose in 32 U.S. jurisdictions, found that incidence among unvaccinated persons was 14 times that among vaccinated persons (95% CI = 5.0-41.0) (4). During September 4-October 1, 2022, a total of 205,504 persons received JYNNEOS vaccine dose 2 in the United States.(§) To further examine mpox incidence among persons who were unvaccinated and those who had received either 1 or 2 JYNNEOS doses, investigators analyzed data on 9,544 reported mpox cases among men(¶) aged 18-49 years during July 31-October 1, 2022, from 43 U.S. jurisdictions,** by vaccination status. During this study period, mpox incidence (cases per 100,000 population at risk) among unvaccinated persons was 7.4 (95% CI = 6.0-9.1) times that among persons who received only 1 dose of JYNNEOS vaccine ≥14 days earlier and 9.6 (95% CI = 6.9-13.2) times that among persons who received dose 2 ≥14 days earlier. The observed distribution of subcutaneous and intradermal routes of administration of dose 1 among vaccinated persons with mpox was not different from the expected distribution. This report provides additional data suggesting JYNNEOS vaccine provides protection against mpox, irrespective of whether the vaccine is administered intradermally or subcutaneously. The degree and durability of such protection remains unclear. Persons eligible for mpox vaccination should receive the complete 2-dose series to optimize strength of protection(††) (5).

In December 2020, two COVID-19 vaccines (Pfizer-BioNTech and Moderna) received Emergency Use Authorization from the Food and Drug Administration.*(,)(†) Both vaccines require 2 doses for a completed series. The recommended interval between doses is 21 days for Pfizer-BioNTech and 28 days for Moderna; however, up to 42 days between doses is permissible when a delay is unavoidable.(§) Two analyses of COVID-19 vaccine administration data were conducted among persons who initiated the vaccination series during December 14, 2020-February 14, 2021, and whose doses were reported to CDC through February 20, 2021. The first analysis was conducted to determine whether persons who received a first dose and had sufficient time to receive the second dose (i.e., as of February 14, 2021, >25 days from receipt of Pfizer-BioNTech vaccine or >32 days from receipt of Moderna vaccine had elapsed) had received the second dose. A second analysis was conducted among persons who received a second COVID-19 dose by February 14, 2021, to determine whether the dose was received during the recommended dosing interval, which in this study was defined as 17-25 days (Pfizer-BioNTech) and 24-32 days (Moderna) after the first dose. Analyses were stratified by jurisdiction and by demographic characteristics. In the first analysis, among 12,496,258 persons who received the first vaccine dose and for whom sufficient time had elapsed to receive the second dose, 88.0% had completed the series, 8.6% had not received the second dose but remained within the allowable interval (≤42 days since the first dose), and 3.4% had missed the second dose (outside the allowable interval, >42 days since the first dose). The percentage of persons who missed the second dose varied by jurisdiction (range = 0.0%-9.1%) and among demographic groups was highest among non-Hispanic American Indian/Alaska Native (AI/AN) persons (5.1%) and persons aged 16-44 years (4.0%). In the second analysis, among 14,205,768 persons who received a second dose, 95.6% received the dose within the recommended interval, although percentages varied by jurisdiction (range = 79.0%-99.9%). Public health officials should identify and address possible barriers to completing the COVID-19 vaccination series to ensure equitable coverage across communities and maximum health benefits for recipients. Strategies to ensure series completion could include scheduling second-dose appointments at the first-dose administration and sending reminders for second-dose visits.