SAFER: SARS-CoV-2 Acquisition in Frontline Health Care Workers – Evaluation to Inform Response

Project 26 Mar 2020

The global outbreak of SARS-CoV-2 (also known to the public as ‘coronavirus’) which leads to COVID-19 has reportedly resulted in a 3% case fatality rate globally, making it a more severe infection than seasonal or pandemic 2009 influenza. Patients in hospital are at risk of catching SARS-CoV-2 during their admission since they may share open bays with other patients who have the virus before they are isolated. We have seen that patients who are immunocompromised, immunosuppressed and extremes of age are more likely to have severe illness and even die from Covid-19. We know that some people have SARS-CoV-2 and are asymptomatic. It is not clear whether those people can pass this infection on to others.

Health care workers who work during a pandemic are at risk in two ways:

  • They are at risk of catching the infection from their patients, who may be infected but not suspected or isolated.
  • They are also at risk of carrying the infection during work and passing it to their colleagues or patients.

It is not clear which staff are more at risk; those in A&E or those who work in cohort wards (that is, wards dedicated to patient care of SARS-CoV-2 positive patients). Staffing challenges are experienced due to concerns regarding the risks of acquisition of SARS-CoV-2.


The SAFER study will examine rates of SARS-CoV-2 acquisition in HCWs at the University College London Hospital (UCLH) and at Liverpool University Hospitals NHS Foundation Trust, at Royal Liverpool University Hospital (RLUH). We are also interested to know whether the presence of nasal bacteria (specifically a bacterial called Streptococcus pneumoniae) is associated with increased risk of SARS-CoV-2 infection and Covid-19 disease.


This study will allow us to:

  • Better inform staff of risks from working during a pandemic and better understand how to protect them
  • Help us find ways of reducing the risk of transmission of SARS-CoV-2 to patients
  • Learn about the role of asymptomatic carriage, co-pathogens (including Streptococcus pneumoniae) and host immune responses.


One hundred staff members from A&E and various wards at the RLUH will be invited to take part if:

  • They are 18 years of age or older, and
  • Work in one of the designated areas for at least 5 hours for at least 1 day during the study period

Participants can work in any role (e.g. nurses, clinicians, ward clerks, nursing assistants, pharmacists). Participants will be asked to take part in the study for 3 months. They will:

  • Self-administer nose and throat swabs twice per week and complete a brief symptom and contact checklists. These will be collected from designated collection points at the RLUH.
  • Collect ‘nasosorption’ and saliva samples each week at home. Nasosorption is a small piece of blotting paper held inside the nose for 2 minutes to collect nasal fluid. Participants will spit a small amount of saliva into a tube using a funnel. These samples will be stored in the participants' freezer and returned to the study team each month using a cool bag.
  • Have a blood sample each month taken by a study nurse, arranged at a suitable time for the participant, in hospital.
  • Complete a brief baseline questionnaire, providing information about yourself, your role in the hospital and baseline health status. If you prefer not to share health data, you will be able to indicate that on the form.

Training and instructions will be provided on how to collect samples. We will provide all equipment to enable participants to do this and to store the samples for a period of time at home. We know staff are busy when at work and require undisturbed break times. We will come onto the ward frequently to provide reminders and support.

Project Team:

The study team is being led by Dr. Naomi Walker. If you are interested in taking part, you can contact the Respiratory Clinical Research Group at the Liverpool School of Tropical Medicine by calling 07740 410 290 or emailing

Full study information can be found here.

Thank you for your interest in our study!