Date to MMWR Disease Week — mmwr

Following CDC MMWR schema, calculate week number based on input date.

Usage

mmwr_week(date)

Arguments

date: Input date i.e. episode date, specimen collection date.

Value

Epidemiological week per MMWR schema.

Details

From CDC: The first day of any MMWR week is Sunday. MMWR week numbering is sequential beginning with 1 and incrementing with each week to a maximum of 52 or 53. MMWR week #1 of an MMWR year is the first week of the year that has at least four days in the calendar year. For example, if January 1 occurs on a Sunday, Monday, Tuesday or Wednesday, the calendar week that includes January 1 would be MMWR week #1. If January 1 occurs on a Thursday, Friday, or Saturday, the calendar week that includes January 1 would be the last MMWR week of the previous year (#52 or #53). Because of this rule, December 29, 30, and 31 could potentially fall into MMWR week #1 of the following MMWR year.

Examples

episode_date = as.Date("2020-01-14")
mmwr_week(episode_date)
#> [1] 3