The recent rise in infections with the Omicron variant of the SARS-CoV-2 is alarming. Equally disconcerting is the fact that individuals who were previously vaccinated (< 6 months) and have co-morbidities that are considered high risk, are getting re-infected...a process referred to as "breakthrough". There is some evidence that in these high risk individuals, the gradual decrease in immunity against the virus as depicted by a drop in anti-SARS-CoV-2 antibodies, is responsible (partially or wholly) for this reinfection. In this study, we intend to give a booster does Pfizer/BioNTech and/or Moderna and ascertain the levels of antibodies at various times pre and post vaccination. The incidence of infection with SARS-CoV-2 after booster vaccination will also be obtained.

Inclusion Criteria:

• Adults 18 years and over that have been fully vaccinated (2 doses) with the Pfizer/BioNTech COVID-19 vaccine (BNT162b2) and with the 1st booster at least 90 days prior to the 2nd booster
• Healthcare workers employed by and/or affiliated with DHR Health, Renaissance Medical Foundation, DHR Partners, Starr County Memorial Hospital
• Any adult with any of the following risk factors for severe COVID-19 disease progression (as outlined by the CDC)

Exclusion Criteria:

• Previous history of allergic reaction to vaccination
• less than or equal to 3 months from last booster dose of vaccine
• active SARS-COV-2 infection
• less than or equal to 21 days of full recovery from SARS-CoV-2 infection
• less than or equal to 14 days of any vaccination
• vaccinated with any other available COVID-19 vaccine other than Pfizer/BioNTech or Moderna
• Healthcare workers not employed by and/or affiliated with DHR Health, Renaissance Medical Foundation, Star County Memorial Hospital or non DHR Partners