In November 2022, the SARS-CoV2 Immunity and Reinfection Evaluation Study, or SIREN for short, was expanded to study influenza and respiratory syncytial virus (RSV).
The COVID-19 pandemic provided a masterclass in how to rapidly shape understanding of the virus, with new studies, unprecedented levels of data collected, and multiple units of dedicated researchers tasked with transforming this data into answers about the virus.
What is SIREN?
SIREN is a nationwide survey involving more than 44,000 healthcare workers in 135 NHS organisations. The SIREN study was set up at the start of the COVID-19 pandemic and we have been following participants for two years now, collecting regular PCR swabs and blood samples from an incredibly dedicated group of NHS staff who volunteer their time.
Influenza or influenza is a highly contagious respiratory virus. Flu season in the UK runs from roughly October to March, with most cases occurring between December and February.
Every year, flu is the focus of health workers and researchers aiming to protect the UK population. This includes developing and introducing a vaccine, providing a seasonal information campaign about the virus, and treating those who do get sick.
We saw a decrease in influenza transmission, which led to a decrease in influenza rates during the COVID-19 pandemic, thanks to social distancing measures and the widespread use of face coverings. The weakening of these measures means that influenza is circulating at higher levels, increasing the burden on healthcare facilities.
SIREN will also study the impact of RSV infection on healthcare workers as part of this extension. Like the flu, RSV is a highly contagious respiratory virus and accounts for more than half a million doctor appointments and more than 40,000 hospitalizations each year, mostly affecting young children and the elderly.
Gaps in our knowledge
It’s been a tough winter for the NHS and we know that flu takes its toll on the system every year. It is important to learn more about the burden of influenza and other respiratory viruses on both the NHS and the wider population. We currently do not have accurate estimates of the level of influenza circulating among healthcare workers.
One reason for this is that we don’t know how many people have the flu without symptoms. In addition, we do not yet understand how the flu interacts with COVID-19 and what impact this may have. This is especially important now that we have entered a phase of the pandemic where protective measures have been reduced and influenza and COVID-19 are circulating simultaneously.
Knowing more about influenza, along with RSV and COVID-19, can help hospitals and policymakers plan effectively for future winters. It is critical to understand the extent of the burden of respiratory viruses on healthcare workers so that employers can take care of the health and well-being of staff, which in itself is important and is the foundation of high-quality patient care.
How the SIREN study attempts to fill these knowledge gaps
Analysis of SIREN samples has helped the UK assess the immune response to COVID-19, provided insight into re-infections of COVID-19 and helped us understand the level of protection offered by vaccines. SIREN has helped answer some of the most pressing questions about COVID-19, enabling decision-makers, both nationally and locally, to control the spread of the disease.
SIREN is now focusing on influenza and RSV as well as COVID-19. SIREN is uniquely placed to study the impact of additional respiratory viruses, making the most of the samples provided by our fantastic team, the data systems we have built and the research collaborations we have established in the UK to help answer the most pressing questions.
Some of the key questions we hope to answer are:
- What are the flu rates in healthcare workers?
- How many people with the flu have no symptoms?
- How effective is the flu shot against infection?
- What symptoms do participants experience with respiratory infections?
- How many sick days do respiratory viruses cause in healthcare workers?
We would like to thank the NHS organisations, research teams and laboratory staff across the UK who made the SIREN Influenza and Winter Pressure sub-study possible, in addition to every NHS staff who took part; we couldn’t do it without you.
The SIREN influenza and winter stress sub-study is funded by the UKHSA with support from Public Health Scotland, Public Health Wales and the Public Health Agency of Northern Ireland. We are pleased to share that the substudy has also recently received grant funding from Health Data Research UK (HDR UK). SIREN is one of 16 research studies selected to investigate how to mitigate the winter pressures facing the NHS.
More information about the SIREN study can be found here.