All New York City employers will have to mandate COVID-19 vaccinations for their workers under new rules announced Monday by Mayor Bill de Blasio. The vaccine mandate for private businesses will take effect Dec. 22 and is aimed at preventing a spike in COVID-19 infections during the holiday season and the colder months.

Under new mandates for indoor dining, entertainment and gyms, two shots will also be required for people over 12. One shot will be required for children aged 5 to 11, who are not covered by the current mandate, de Blasio said.

The omicron variant is in New York, New Jersey and Connecticut right now. Many questions about the variant remain, including precisely how transmissible it is, how well vaccines will hold up against it and how likely it is to cause severe disease.

A study suggests the omicron variant may overcome immunity protection from previous COVID-19 infection. South African scientists are warning that reinfections among people who've already battled COVID-19 appear to be more likely with the new omicron variant than with earlier coronavirus mutants.

Can we rely on rapid COVID-19 tests?

Is the best strategy against omicron to boost with the original vaccine, or wait? Are there different side-effects we should be concerned about?