Influenza activity typically peaks between the months of December and February, and with flu season in full swing, the Centers for Disease Control and Prevention recommends everyone 6 months and older receive a vaccine.

Included in a report from the CDC on the 2017-18 influenza season and flu vaccines are recommendations from the Advisory Committee on Immunization Practices. Based off this report and other recommendations from the CDC, here are five important things to know about the 2017-18 flu season.

1. No Nasal Spray Flu Shots: The CDC is keeping last year’s recommendation to not use the nasal spray flu vaccine (LAIV) for the 2017-18 season. The CDC recommends to only use injectable flu shots this season.

2. Different vaccines are available for different people: Age, health status and allergies are all factors that determine a person’s aptness for vaccination or a particular vaccine. This flu season, the ACIP recommends either the inactivated influenza vaccine (IIV) or the recombinant influenza vaccine (RIV).

3. There are two main flu vaccines available this season: Trivalent (three component) and quadrivalent (four component) flu vaccines are available this season.
• Trivalent flu vaccines include standard-dose trivalent shots (IIV3) for persons aged 18-64 years, a high does trivalent shot for persons 65 years and older, an egg-free recombinant trivalent shot for people 18 years and older and a new trivalent shot that helps create a stronger immune response for people 65 and older.
• Quadrivalent flu vacinnes include the intradermal shot approved for people 18-64 years, a quadrivalent flu shot made with viruses approved for people 4 years and older and a recombinant quadrivalent shot that is new this season and approved for people 18 years and older.

4. Getting a flu shot does not guarantee protection against the flu: It is still possible to get the flu even after being vaccinated. Age, health status and the type of vaccination can all contribute to a person’s chances of getting the flu. Vaccine effectiveness can be reduced if viruses in the vaccine a person receives are not closely matched with the viruses circulating in the community, according to the CDC.

5. It is not too late to get a flu shot: While the CDC recommends people to get flu shots by the end of October and early fall, people who have not been vaccinated are encouraged to do so up until the end of the flu season and into January or later, as long as vaccines are available and the influenza virus is still spreading.