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COVID-19 reinfection FAQs

How to approach high-risk exposures in paramedics previously infected with SARS-CoV-2


Can COVID-19 reinfection occur? Will a second infection be mild or more severe? Learn the answers to these questions and more.

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Since the novel coronavirus, now known as COVID-19, was identified in December 2019, several notable variants of the virus have been discovered. Learn what health experts have to say about these new variants and how the newly released COVID-19 vaccines will fare against them: COVID-19 variants: What first responders need to know

By Casey Patrick, MD, FAEMS; and Robert Dickson, MD, FAEMS

As the first anniversary of the COVID-19 pandemic approaches, more questions have developed around the area of potential SARS-CoV-2 reinfection. It is currently unknown how long immunity lasts following infection, but past coronavirus literature suggests that prolonged protection is far from guaranteed.

Additionally, it is unclear if the presence of SARS-CoV-2 antibodies even ensures protection from the disease. This research, like the disease itself, is in its infancy. Over the past few weeks, the initial round of case reports of reinfection has begun rolling out for journal release. Below are the best answers to some practical questions regarding reinfection risk and COVID-19 exposure post-infection.

Can COVID-19 reinfection occur?

Data is accumulating that true reinfection can occur in SARS-CoV-2. In October, Lancet published one of the first U.S. reinfections in a 25-year-old male patient from Nevada [1]. There were 48 days between his illnesses, and his second round was actually much worse than the initial (requiring hospitalization). Other case reports have shown timing between episodes of infection ranging from 63-143 days [2-5].

How are we sure this is reinfection and not relapse?

In all of these case reports, genomic analysis demonstrated different SARS-CoV-2 sequences between the initial infection and the second infection [1-5]. This genetic variation makes relapse of the initial virus highly unlikely. Additionally, all of these case report patients had negative PCR tests between illnesses, and none were immunocompromised.

But the second infection was milder right?

Unfortunately, in two of the genetic sequence confirmed reinfection case reports, the secondary infection was, unfortunately, worse than the initial, and one even required hospitalization [1-5]. Antibody testing in these case reports was incomplete. More data is needed to determine if there is any utility in antibody screening protocols.

Does this mean SARS-CoV-2 is mutating?

These genomic differences between infections are useful to rule out latent infection/relapse, but they do not suggest mutation due to immune evasion. Immunologists still feel that vaccine candidates should match all circulating variants [6].

How should we approach high-risk exposures in a paramedic who previously had COVID-19?

Unfortunately, the most current data suggests that past infection does not reliably confer immunity and that reinfection can occur less than two months from the initial infection [2-5]. Additionally, the secondary infection has the potential to be clinically more severe than the initial illness. This evidence points to the safest approach being one of continued diligence following initial COVID-19 infection.

What exactly does continued diligence mean?

Mask wearing is a must at all times, including while inside the station, unless you’re in your bedroom sleeping. All group activities, such as shared space meals, must be eliminated. Your family must continue to use infection control methods, including masking and hand washing as well. A majority of EMS high-risk exposures are not due to direct patient contact, but from our life outside patient care. With the continued rise in COVID-19 cases, now is not the time to let our defenses slip.

Read next: Mike Taigman’s 5-step wellness check-up to survive and thrive during COVID-19

About the authors

Dr. Casey Patrick is the assistant medical director for Montgomery County Hospital District EMS and is a practicing emergency physician in multiple community emergency departments across Greater Houston. His EMS educational focus is on innovative paramedic teaching via the MCHD Paramedic Podcast. Dr. Patrick’s prehospital clinical research involves the investigation of paramedic use of bolus dose intravenous nitroglycerin for acute pulmonary edema and the implementation of lung protective ventilation strategies for intubated EMS patients. Casey and his wife, Alyssa, work and live in Conroe, Texas, and Spokane, Washington. Together they have five children: Mia, Ainsley, Brock, Dean and Will.

Dr. Dickson graduated with honors from the University of Texas Health Science Center San Antonio in 2001 and completed emergency medicine training at Indiana University in 2004. He serves as the EMS medical director at Montgomery County Hospital District EMS and an assistant professor of emergency medicine at Baylor College of Medicine in Houston, Texas. His academic interests include systems of care in stroke and other time-sensitive emergencies, neurologic emergencies and education. He is board certified in emergency medicine in both the U.S. and Australasia, and has subspecialty board certification in EMS medicine. He has authored multiple professional articles and presented at regional, national and international conferences on emergency medicine and EMS topics.


  1. Iwasaki A. What reinfections mean for COVID-19. Lancet Infect Dis. 2020; (published online Oct 12.)
  2. Tillett RL, Sevinsky JR, Hartley PD, et al. Genomic evidence for reinfection with SARS-CoV-2: a case study. Lancet Infect Dis 2020; published online Oct 12.
  3. To KK-W, Hung IF-N, Ip JD, et al. COVID-19 reinfection by a phylogenetically distinct SARS-coronavirus-2 strain confirmed by whole-genome sequencing. Clin Infect Dis 2020; published online Aug 25.
  4. Van Elslande J, Vermeersch P, Vandervoort K, et al. Symptomatic SARS-CoV-2 reinfection by a phylogenetically distinct strain. Clin Infect Dis 2020; published online Sept 5.
  5. Prado-Vivar B, Becerra-Wong M, Guadalupe JJ, et al. COVID-19 reinfection by a phylogenetically distinct SARS-CoV-2 variant, first confirmed
    event in South America. SSRN 2020; published online Sept 8. (preprint).
  6. Dearlove B, Lewitus E, Bai H, et al. A SARS-CoV-2 vaccine candidate would likely match all currently circulating variants. Proc Natl Acad Sci USA 2020; 117: 23652–62.
Dr. Casey Patrick is medical director for the Montgomery County Hospital District EMS service in Greater Houston, where he helped develop and produces the MCHD Paramedic Podcast. Dr. Patrick is board certified in both Emergency and EMS Medicine and works as a community emergency physician in multiple states. Additionally, he is an active member of the Texas NAEMSP State chapter and the national association, and serves as an EMS1 Editorial Advisory Board member.