Skip to contents

Get the first date of an epidemiological year ("epiyear")

Source: R/epiweek_to_date.R
epiyear_first_date.Rd

For the ISO, the epidemiological year ('epiyear') YYYY begins on the Monday of the Monday to Sunday week that includes January 4.

Usage

epiyear_first_date(epiyear, epiweek_standard = "USA")

Arguments

epiyear

The epidemiological year for which to get the first date.

epiweek_standard

One of "USA" (USA epiweek, starts on Sunday) and "ISO" (ISO week, starts on Monday). Not case-sensitive. Default "USA".

Value

The first date of the epiyear, as a 'lubridate::date object

Details

The US CDC / MMWR epiyear is analogous but with a Sunday to Saturday week. That is, it begins on the Sunday of the Sunday to Saturday week that includes January 4.

Both of these definitions ensure that an epiyear always starts on the first day of a seven day week (Monday for ISO, Sunday for US CDC/MMWR), and specifically on whichever first day of the week falls nearest to 1 January.