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Pre-print: Understanding Outcomes of COVID-19 Treatments including Antivirals and Antibodies across Scotland

March 2023: Scottish study looks at the risk of people experiencing serious COVID-19 illness after being treated with antivirals and/or neutralising monoclonal antibodies, and estimates how effective these treatments are compared to one another

Real-World Severe COVID-19 Outcomes Associated with Use of Antivirals and Neutralising Monoclonal Antibodies: A Population-Based Retrospective Cohort Study in Scotland

Tibble, H; Mueller, T; Proud, E; Hall, E; et. al.

preprints with The Lancet

Published online on: 2 March 2023

Available online at: https://papers.ssrn.com/sol3/papers.cfm?abstract_id=4356763

Summary in plain English

Why did we carry out this work?

In response to Covid-19 pandemic, a number of drugs have been introduced or used in different ways. These drugs include antivirals (virus fighting medicines) and neutralising monoclonal antibodies (laboratory made antibodies that mimic natural ones).  Over the course of last two years UK guidelines for Covid-19 therapeutics have been updated on the basis of research results. We analysed, collected and linked data to describe clinical outcomes after treatment with the two types of drugs named above. Patients and the public have helped us with the design and interpretation of this study.

What data did we do this?

This was a study which looked back and observed clinical outcomes of hospitalisation, Intensive Care Unit (ICU) admission and death in people treated for Covid-19 in Scotland. The data used in the study on drug exposure were linked to additional datasets:

  • The Scottish Morbidity Records inpatient dataset (SMR01)
  • Rapid Preliminary Inpatient Data (RAPID)
  • SICSAG episode-level ICU admissions data
  • National Records of Scotland (NRS) mortality records
  • SARS-CoV-2 testing data (from the ECOSS)
  • Covid-19 vaccinations (Turas Vaccination Management Tool and GP records)
  • SARS-CoV-2 virus sequencing (combining qualitative and quantitative) data

Comorbidities (presence of two or more illnesses) were estimated from data on:

  • In-hospital-conducted medical procedures (e.g. transplants and chemotherapy)
  • GP records
  • Primary care prescription data (PIS)

In this study the drugs of interest were: molnupiravir, Paxlovid, remdesivir, sotrovimab, sarilumab and tocilizumab. Information on the prescription or administration of these drugs was provided directly from 13 of 14 Health Boards. Additional data was received by 6 Health Boards from the Hospital Prescribing and Medicines Administration System (HEPMA).

Clinical outcomes we analysed, included hospital and ICU admissions, and deaths (of any cause and Covid-19) within 28 days of starting treatment. The population groups involved in this study were assigned to 1 of 4 groups:

  • Group 1 – people hospitalised for acute Covid-19
  • Group 2 – people who were in hospital for more than 2 weeks or with concurrent (at the same time) Covid-19
  • Group 3 – people treated outside of a hospital
  • Group 4 – uncoded hospital patients who could not be classified as Group 1 or 2

Not all Covid-19 patients were eligible for treatment. Therefore, we did not compare clinical outcomes between the treated and untreated. Eligibility depended on those who had existing health conditions, medication taken and severity of Covid-19.

What did we find?

There were 14,635 Covid-19 treatment events identified in datasets coming from Scotland. 80% of them were in the outpatient or community setting for non-severe Covid-19.

21.8% of those treated for acute Covid-19 in a hospital setting and released within 28 days of starting treatment were admitted again within 28 days. There were only 2.8% patients treated in hospital with hospital-onset or concurrent Covid-19.

Of those people treated outside hospital, only 1.1% had an admission within 28 days. Group 3 patients who were treated with combination of therapies (likely to be the highest risk patients) had the highest chances of hospital admission or dying within 28 days of starting treatment.

Factors such as having fewer than 3 Covid-19 vaccinations, a diagnosis of blood cancer or chronic kidney disease, taking immunosuppressants, previous chemotherapy or a solid organ transplant were all linked with higher odds of Covid-19 hospitalisation.

During the period in which BA.5 has been the most predominant variant in the UK, sotrovimab was associated with the lowest risk of severe outcomes in Group 3 patients.

Why is this important


The number of patients given each treatment type have changed over time. It is safe to assume that the characteristics of patients treated with each medication have changed in response to new guidelines and evidence.

This study has its limitations. This includes exploring comparisons of clinical outcomes between different treatments may not identify differences in patient characteristics. For example severity, comorbidities and medications taken at the same time.

Due to the lack of data on Covid-19 symptoms, we were unable to compare untreated patients. For instance, high-risk patients who did not show symptoms or those who refused treatment. As a result, we could not provide a strong and meaningful evaluation of improvement in clinical outcomes.


This summary was written by Research Administrator Laura Gonzalez Rienda, and reviewed by members of our analyst team and Patient Advisory Group.