Each COVID-19 vaccine requires a second dose

Moderna - 2nd dose 28 days after the first dose
Pfizer - 2nd dose is 21 days after the first dose

The second dose must be from the same manufacturer.  When you got your first dose they gave you a card telling you which vaccine you received and when you are due for the second dose.

If you receive the first dose at Nassau Community College you will be able to make an appointment for the second dose on the County website.  The site will be updated this weekend (1/10/21) with a link for scheduling the second dose appointment.

Go to this link:
Second Dose Appointment

If you receive the first dose at Nassau University Medical Center, they will assign you the appointment for your second dose at exactly 4 weeks after your first appointment.