For more information: www.cdc.gov/COVID19

Interim Clinical Considerations for

Pfizer-BioNTech COVID-19 Vaccine 

Booster Doses

Kathleen Dooling, MD, MPH

September 23, 2021
Definition of ‘fully vaccinated’

 For public health purposes, people who have completed a primary vaccine 

series (i.e. 2-dose mRNA vaccine series or a single dose of the Janssen 

vaccine) are considered fully vaccinated ≥2 weeks after completion of the 

primary series

 The above definition applies to all people including those who receive an 

additional dose as recommended for moderate to severely 

immunocompromised people and those who receive a booster dose

https://www.cdc.gov/coronavirus/201 9-ncov/vaccines/fully-vaccinated.html
Administration- Booster dose

 Pfizer-BioNTech COVID-Vaccine (BTN162b2), 0.3ml, intramuscular 

administration

 Timing: ≥6 months after completion of the primary series

– Immunity wanes gradually over time, therefore a booster may be given 

at an interval greater than 6 months

 Co-administration: a Pfizer-BioNTech COVID-Vaccine booster dose may be 

given with other vaccines, without regard to timing. This includes 

simultaneous administration of COVID-19 and other vaccines on the same 

day.
Groups at risk for severe COVID-19 or

SAR-CoV-2 infection after primary series 

vaccination
Age-Based Group: people aged ≥ 65 years

 Increased risk of severe COVID-19 (including hospitalization and death) this 

age group of fully vaccinated people compared to younger fully vaccinated 

people

 Waning of COVID-19 vaccine effectiveness against severe disease has been 

observed in people aged ≥65yrs
Risk-Based Group: Long Term Care Facility (LTCF) residents 

 Residents of LTCFs, aged ≥18 years

 Likely increased risk of severe COVID-19 (including hospitalization and death) 

among fully vaccinated residents compared to fully vaccinated people living 

independently

 Waning of COVID-19 vaccine protection against infection has been observed 

in LTCF residents

 Congregate living setting associated with increased risk of COVID-19
Risk-Based Group: occupation or setting

 Aged ≥18 years

 Fully vaccinated persons may be at increased risk of SARS-CoV-2 infection due 

to occupation or setting 

 Absence from occupation due to SARS-CoV-2 infection may hinder societal 

functions

Examples

 Essential workers* (frontline and non-frontline)

 Unpaid caregiver of a frail or immunocompromised person

 Paid and unpaid workers who interact within <6ft of others

 Live in a congregate setting (e.g. homeless shelter, correctional facility)

* Guidance on the Essential Critical Infrastructure Workforce | CISA
Risk-Based Group: underlying medical conditions 

 Aged ≥18 years

 Fully vaccinated persons with underlying medical conditions may be at risk of severe 

COVID-19 if they become infected with SARS-CoV-2

Examples:

• Cancer

• Cerebrovascular disease

• Chronic kidney disease

• COPD (chronic obstructive pulmonary 

disease)

• Diabetes mellitus, type 1 and type 2

• Heart conditions (such as heart failure, 

coronary artery disease, or 

cardiomyopathies)

• Obesity (BMI ≥30 kg/m2)

• Pregnancy and recent pregnancy

• Smoking, current and former

Underlying Medical Conditions for Clinicians (cdc.gov)
Considerations for the individual level 

assessment of benefits and risks of a 

COVID-19 booster dose
Considerations for the individual level assessment of 

benefits and risks of a COVID-19 booster dose

Potential Benefits

 May confer reduced risk of severe disease

– Strongest evidence in older adults

– Vaccine effectiveness of an mRNA primary series remains high in younger age groups

 May confer reduced risk of SARS–CoV-2 infection

– Waning of vaccine protection via a combination of time since vaccination and delta 

variant has been observed in most age groups

– Infection may be symptomatic or asymptomatic

– May reduce work absence and preserve capacity of important sectors

– May reduce transmission of SARS-CoV-2 infection to other at-risk persons 
Considerations for the individual level assessment 

of benefits and risks a COVID-19 booster dose

Potential risks

 Myocarditis and myopericarditis, although very rare, may occur following mRNA 

vaccination. It is more common in younger age groups, particularly males aged <30 

years.

– Most patients with myocarditis have been hospitalized for short periods, with the 

majority achieving resolution of acute symptoms

– The rate of myocarditis following a booster dose is not yet known

 Anaphylaxis, although rare, may occur following mRNA vaccination. The rate of 

anaphylaxis following a booster dose is not yet known

 Reactogenicty, including transient local and systemic symptoms, are common 

following mRNA vaccines. The 3rd dose of Pfizer-BioNTech COVID-19 vaccine appears 

to have similar reactogenicity as the 2nd dose.
Considerations for the individual level assessment 

of benefits and risks a COVID-19 booster dose

Consider individual risk of SARS-CoV-2 exposure

 Risk of exposure in occupational, living and transportation settings

 Ability to consistently wear a mask, maintain social distance, and other mitigation measures

 Rates of SAR-CoV-2 infection in the community

Consider individual risk of developing severe COVID-19, if infected

 Underlying medical conditions, particularly if not well controlled

Consider personal characteristics

 Living with or caring for a frail or immunocompromised person

 Consequences of inability to meet personal or occupational obligations due to SARS-CoV-2 

infection
Contraindications, Precautions &

other Adverse Events Following Immunization
Contraindications & Precautions

 Severe allergic reaction (e.g., anaphylaxis) after a previous dose or to a 

component of the Pfizer BioNTech COVID-19 vaccine

 Immediate allergic reaction of any severity to a previous dose or known 

(diagnosed) allergy to a component of the vaccine

 Known polysorbate allergy is a precaution to mRNA COVID-19 vaccination
Myocarditis or myopericarditis after a dose of mRNA 

COVID-19 vaccine:

 Recommend deferral of a subsequent dose

 People who choose to receive a sequent dose should wait until myocarditis 

or myopericarditis has completely resolved
Anaphylaxis

 Anaphylactic reactions 

have been rarely 

reported following 

receipt of COVID-19 

vaccines. 

 https://www.cdc.gov/

vaccines/covid19/downloads/Interm

Consid-Anaphylaxiscovid19-vaccinesites.pdf
Additional resources
CDC Resources

Learn more with CDC’s COVID-19 vaccine tools and 

resources. Find information for COVID-19 vaccination 

administration, storage, reporting, patient education, 

and more.

• COVID-19 Vaccination: 

https://www.cdc.gov/vaccines/covid-19/index.html

• For Healthcare Professionals: 

https://www.cdc.gov/vaccines/covid19/hcp/index.html

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Thank you