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Sergio Ramoa MD, MS

Urgent Message: With variant COVID-19 mutations, incomplete herd immunity, and less restrictive government regulatory statues, it is important to remain vigilant with continued testing and prevention even with a full vaccinated history.


In the United States, cases of COVID-19 have passed 32,000,000 and 570,000 for deaths. 141,000,000 cases and 3,000,000 deaths have afflicted the world. Approximately 9.6% of infected individuals are hospitalized and a majority have mild to moderate symptoms.1 As of April 24, 2021, 28% of the U.S. population has been fully vaccinated and 41.8% have received at least one dose, with 81% of that category being over the age of 65.2

Case Presentation

Patient is a 28-year-old male with no past medical history presenting to an urgent care in March 2021 with a 2-day history of clear nasal congestion, dry cough, sore throat, and changes in sensation to smell. The patient is a medical resident and has completed two doses of Pfizer vaccine. He received his doses within the recommended interval, with the first dose on December 20, 2020, and the second dose January 10, 2021. He was followed up 2 days later with resolution of symptoms. Beyond the general exposures of a hospital, his partner was sick 3 days prior to him with similar symptoms. She had completed COVID vaccinations around the same time.

Physical Exam


  • Temperature 98.1⁰F, pulse 61, BP 127/85, 02 saturation 96% RA, BMI 22.2
  • General: Ill-appearing but no apparent distress. Well developed, well nourished
  • ENT: Tympanic membrane without injection and normal position. Nose with increased nasal mucous. Pharynx with mild injection
  • Eyes: Non-injected bilaterally
  • Respiratory: Lungs clear to auscultation bilaterally
  • Skin: Warm and dry


  • Abbott-ID NOW COVID-19 (Molecular)
  • SARS-CoV-2 RdRp gene NAA+ probe QI (resp): positive

Prior to testing, patient already had a high pretest probability of disease based on viral upper respiratory symptoms, anosmia, and increased risk of exposure secondary to his work and partner. False positive rates are low with Abbott testing. COVID-19 symptoms typically present 2 to 14 days after exposure. Average time is 5 days, and by 11 days 95% of people demonstrate symptoms. Of note, the patient’s partner, who had similar symptoms, had negative results on rapid Abbott testing.

The Infectious Diseases Society of America recommends repeat testing 1 to 2 days after if risk and pretest probability is still high.4 By so doing, we attempt to diminish the false negative results. Focus is placed on missing a diagnosis and the threat of spreading to others and the community.


This patient had no concerning risk factors and mild symptoms. Supportive care was recommended. Follow-up in 2 days, by phone, confirmed resolution of symptoms. The patient was recommended to complete the full 10 days of quarantine since symptoms began. His case was reported to the CDC.


Based on previous studies, the Pfizer two-dose vaccine demonstrated 95% effectiveness in preventing COVID-19; efficacy after a single dose is about 52%.5 From the patient’s documented vaccine history, this confirms a COVID-19 breakthrough case. Interestingly, his greatest exposure risk factor was his partner who tested negative. This could be secondary to a false negative. These individuals were at higher risk for infection than the general population due to their occupation in the medical field.

The CDC states that a fully vaccinated person who has received the second vaccine at least 2 weeks prior does not need to quarantine after an exposure. They do not currently have any recommendation on quarantine and length for those that have been fully vaccinated and have been reinfected. There have been a total of 9,000 cases of COVID-19 infection postvaccination. Table 1 reveals related COVID-19–related hospitalization and death.

Table 1. U.S. COVID-19 Cases, Hospitalizations, and Deaths Among Vaccinated Individuals6

Total U.S. vaccinated107,346,533
Total cases9,245 (0.0086%)
COVID-19–related hospitalization594 (6.4%)
Total deaths132 (1.4%)
COVID-19–related deaths112 (1.2%)
*As of April 20, 2021

Studies have shown impressive results with the Pfizer vaccine and risk of infection. In a study with healthcare workers in Israel, the symptomatic infection and asymptomatic infection incidence rate is 0.03 and 0.14, respectively.7

Take-Home Points
Consider testing for COVID-19 even if the patient is fully vaccinated.
Breakthrough COVID infections should be reported to the CDC.
Encourage all eligible patients to be vaccinated.  


  1. Centers for Disease Control and Prevention. COVID Data Tracker Weekly Review. Available at: Accessed May 7, 2021.
  2. Centers for Disease Control and Prevention. CDC COVID Data Tracker. Available at: Accessed April 24, 2021.
  3. Dinnes J, Deeks JJ, Berhane S, et al. Rapid, point-of-care antigen and molecular-based tests for diagnosis of SARS-CoV-2 infection. Cochrane Database Syst Rev. 2021;3:CD013705. Published 2021 Mar 24.
  4. Hanson KE, Caliendo AM, Arias CA, et al. Infectious Diseases Society of America Guidelines on the Diagnosis of COVID-19: Molecular Diagnostic Testing. Infectious Diseases Society of America 2020; Version 2.0.0. Available at Accessed April 23, 2021.
  5. Polack FP, Thomas SJ, Kitchin N, et al. Safety and efficacy of the BNT162b2 mRNA COVID-19 Vaccine. N Engl J Med. 2020;383(27):2603-2615.
  6. Centers for Disease Control and Prevention. COVID-19 breakthrough case investigations and reporting. Available at: Accessed May 5, 2021.
  7. Angel Y, Spitzer A, Henig O, et al. association between vaccination With BNT162b2 and incidence of symptomatic and asymptomatic SARS-CoV-2 Infections among health care workers. JAMA. Published online May 06, 2021.

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