If you have taken one of my courses, you have likely heard me talk about the Académie Française, the "Supreme Court of the French language," as I like to call it. It is a council that decrees what is officially correct in the French language. When new words arise, the council makes decisions about their use. One new term that we are all certainly using on a daily basis is Covid-19. In French all words have either a masculine or feminine article (le or la) that precede them. Which would Covid be? The Académie has spoken: Covid is officially a feminine word and should be referred to as "la Covid." Prior to the official ruling, many French news organizations had been calling the disease "le Covid," using the masculine article. You can read more about it in this article from The Guardian.
Masculine and feminine articles aren't an issue in English, of course, but I've found myself wondering about proper capitalization of Covid-19. For English we have no official governing body to inform us of how to correctly use new terms. The AP Stylebook recently put out guidelines, however, and they assert that the disease should be written with all capital letters: COVID-19. This is how the WHO writes it. Despite this, the New York Times is spelling it Covid-19, following their editorial guidelines that say acronyms of five or more letters require the capitalization of only the first letter. The Washington Post, meanwhile, uses all lowercase letters: covid-19. The Denver Post is following the WHO and is using COVID-19. All three versions are clearly in widespread use, so it's up to individual preference at this point.
And speaking of the WHO, it should be pronounced as an initialism, that is, saying each letter, rather than as an acronym. The organization refers to itself without the article the (e.g., "WHO guidelines will be released today.") However, news organizations routinely use the article the when referencing the organization in English (e.g., "The WHO will release guidelines today.") One last thing, style guides disagree on using periods with initialisms. The AP Stylebook recommends using them after the letters in only two letter initialisms (e.g., U.N.), but some news organizations use them for three letter abbreviations as well, and will print W.H.O.