• For surveillance purposes, COVID Data Tracker counts people as being "fully vaccinated" or as having "completed a primary series" if they received two doses on different days (regardless of time interval) of the two-dose mRNA series or received one dose of a single-dose vaccine. When the vaccine manufacturer is not reported, the recipient is considered fully vaccinated with two doses.

• For surveillance purposes, the count and percentage of people who received a first booster dose includes anyone who is fully vaccinated and has received another dose of COVID-19 vaccine since August 13, 2021. This includes people who received a first booster dose and people who received an additional primary series dose as this metric does not distinguish if the recipient is  immunocompromised and received an additional dose.
• First booster dose eligibility:
  • CDC counts people as being " eligible for a first booster dose" if it has been at least 5 months since completion of a Pfizer-BioNTech or Moderna primary series or at least 2 months since receipt of a Janssen (Johnson & Johnson) singe-dose vaccine.

• For surveillance purposes, the count and percentage of people who received a second booster dose includes anyone who is fully vaccinated and has received two subsequent doses of COVID-19 vaccine since August 13, 2021. This includes people who received two booster doses and people who received one additional dose and one booster dose. 
• The count of people who received a second booster dose and the percentage of people with a first booster who received a second booster dose does not account for whether a person is immunocompromised or time interval since first booster dose.
• Second booster dose eligibility:
  • CDC counts people as being  "eligible for a second booster dose"  if it has been at least 4 months since receiving a first booster dose.
• Limitations to counting people with a second booster dose:
  
  • Due to the aggregate vaccination record reporting method used by Idaho for its residents under the age of 18 years and by Texas for all its residents, CDC counts all 4th doses received by these populations as a second booster dose. This includes immunocompromised individuals who received a three-dose primary series and only one booster dose. This limitation may lead to an undercount of people who received the single-dose J&J/Janssen vaccine as their primary series and two booster doses.
  
  

The Vaccine Adverse Event Reporting System (VAERS) online database on CDC WONDER provides counts and percentages of adverse event case reports after vaccination, by symptom, vaccine product, manufacturer, onset interval, outcome category, year and month vaccinated, year and month reported, age, sex and state / territory. The Vaccine Adverse Event Reporting System is a cooperative program for vaccine safety of the Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA). VAERS is a post-marketing safety surveillance program, collecting information about adverse events (possible side effects) that occur after the administration of US licensed vaccines. Data are from the US Department of Health and Human Services (DHHS), Public Health Service (PHS), Food and Drug Administration (FDA)/ Centers for Disease Control (CDC), Vaccine Adverse Event Reporting System (VAERS).