The Briefing provides an at-a-glance view of some important developments in the information universe surrounding COVID-19. The views presented here are solely those of ECRI Horizon Scanning and have not been vetted by other stakeholders.

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Caring for long COVID, or post-acute sequelae of COVID-19, is a prime example of patient-centered—or patient-defined—health care. These patients, often called long haulers, demonstrate that even mild COVID-19 can be life-altering. Moreover, research interest in post-viral syndromes and the possible connection to autoimmune diseases is gaining momentum because of strong patient advocacy. The large cohort of individuals experiencing long COVID represents a substantial data set that could reveal much about post-viral conditions and help many patients.

The risks of long COVID to the health care system are growing. Each new case, whether mild or severe, represents a possible patient with long COVID and now children are also reporting long COVID symptoms. If the proposed 10th edition of the  International Classification of Diseases code for post COVID-19 is finalized for use in October 2021, there will be a more trackable prevalence rate. However, it is possible that many patients with long COVID will have left the health care system due to a lack of specialist centers located outside large urban areas.

A third vaccine dose for immunocompromised people and a new potentially preventive therapy for severe disease (see Topics to Watch) are 2 strategies that might ease the spread and the impact of the Delta variant of the coronavirus. These strategies could be of particular importance in high spread areas where health care facilities are often short-staffed.

Additional Dose of mRNA Vaccine to Prevent COVID-19 in Individuals with Compromised Immune Systems

At a Glance

  • A third dose of messenger RNA (mRNA)-based vaccine at least 28 days after the second dose might increase the immune response of COVID-19 vaccines to reduce infection spread, hospitalizations, and mortality rates in individuals with compromised immune systems.
  • The eligible population can receive a third mRNA-based COVID-19 vaccine dose without a clinician referral or antibody testing. The Centers for Disease Control and Prevention (CDC) endorsed administering third doses of the same brand of mRNA vaccine given earlier to individuals with compromised immune systems. If the mRNA product administered for the initial vaccination series is unavailable or not known, then the patient may receive a different mRNA COVID-19 vaccine.
  • Early evidence shows a third dose induces increases in antibody responses among a substantial proportion of persons who are immunocompromised.
  • Some transplant recipients respond substantially better to current COVID-19 vaccines after the third dose. However, responses appear to be highly patient-specific.
  • On August 12, 2021, the US Food and Drug Administration (FDA) expanded the Emergency Use Authorizations (EUAs) for a third dose of mRNA-based COVID-19 vaccines for individuals with compromised immune systems.

Casirivimab and Imdevimab (REGEN-COV) Post-Exposure Prophylaxis to Prevent COVID-19–Related Complications

At a Glance

  • Casirivimab plus imdevimab (REGEN-COV) is a combination monoclonal antibody therapy authorized for post-exposure prophylaxis of patients who are at high risk for progression to severe COVID-19 and are either immunocompromised or not fully vaccinated.
  • REGEN-COV works by targeting the SARS-CoV-2 spike protein to prevent the virus from entering host cells and replicating, limiting the severity of exposure or infection.
  • Recent phase 3 trial data found that REGEN-COV reduced the risk of symptomatic COVID-19 infection by 81% in individuals over the age of 12 who had household exposure to SARS-CoV-2.
  • On August 10, 2021, the FDA revised the EUA for REGEN-COV for use as a post-exposure prophylaxis.
  • REGEN-COV is free to patients, paid for by the US government, but depending on coverage, patients might pay for the cost of administration.

Commentary in this COVID-19 Scan reflects preliminary views of ECRI Horizon Scanning and internal ECRI stakeholders.
The information contained in this document has not been vetted by other stakeholders.

We welcome your comments on this Scan. Send them by email to

Posted: August 27, 2021

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