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. 2025 Aug 21;74(31):484–489. doi: 10.15585/mmwr.mm7431a3

TABLE. Number and percentage of infants immunized against respiratory syncytial virus through receipt of nirsevimab monoclonal antibody or maternal vaccination, by demographic characteristics — 33 states and District of Columbia,* October 2023–March 2024.

Characteristic No. (%)
Infants who received nirsevimab Pregnant women who received RSV vaccine§
Total, no.
213,659
119,879
Infant’s age at nirsevimab receipt
0–3 days
44,510 (20.8)

4–6 days
36,818 (17.2)

7 days–<1 mo
65,009 (30.4)

1 mo
33,160 (15.5)

2–5 mos
34,162 (16.0)

Mother’s age at RSV vaccine receipt, yrs
18–24

13,105 (10.9)
25–34

70,921 (59.2)
35–49

35,853 (29.9)
Immunization month and year
Sept 2023

501 (0.4)
Oct 2023
9,096 (4.3)
10,235 (8.5)
Nov 2023
39,324 (18.4)
27,866 (23.2)
Dec 2023
44,095 (20.6)
37,938 (31.6)
Jan 2024
43,245 (20.2)
43,339 (36.2)
Feb 2024
43,142 (20.2)

Mar 2024
34,757 (16.3)

Vaccines for Children program eligibility
Eligible
91,817 (43.0)

Ineligible
74,907 (35.1)

Unknown
46,935 (22.0)

Infant’s birth month and year
Oct 2023
47,020 (22.0)

Nov 2023
46,507 (21.8)

Dec 2023
40,941 (19.2)

Jan 2024
34,008 (15.9)

Feb 2024
27,377 (12.8)

Mar 2024 17,806 (8.3)

Abbreviation: RSV = respiratory syncytial virus.

* Includes Alaska, Arizona, Arkansas, California, Connecticut, Delaware, Florida, Illinois, Indiana, Iowa, Kentucky, Louisiana, Maine, Maryland, Michigan, Minnesota, Mississippi, Missouri, Montana, Nevada, New Mexico, New York, Ohio, Oklahoma, Pennsylvania, South Dakota, Tennessee, Utah, Vermont, Washington, West Virginia, Wisconsin, and Wyoming.

Includes infants born during October 1, 2023–March 31, 2024, who received at least 1 dose of nirsevimab during October 1, 2023–March 31, 2024.

§ Includes women (defined in the Immunization Information Systems as persons whose sex was female) who were aged 18–49 years at the time of RSV vaccination and received the vaccine (Abrysvo) during September 1, 2023–January 31, 2024. These women were presumed to be pregnant because RSV vaccination is only recommended for women in this age group if they are pregnant.

The Vaccines for Children program provides vaccines at no cost to uninsured and underinsured children through enrolled public and private health care providers.