Since the vaccine roll out, research has focused on vaccine safety and efficacy, with large clinical trials confirming that vaccines are generally effective against symptomatic COVID-19 infection. However, breakthrough infections can still occur, and the effectiveness of vaccines against transmission from infected vaccinated people to susceptible contacts is unclear.

Health Technology Wales (HTW) collaborated with the Wales COVID-19 Evidence Centre to identify and examine evidence on the transmission risk of SARS-CoV-2 from vaccinated people to unvaccinated or vaccinated people.

We conducted a systematic literature search for evidence on vaccinated people exposed to SARS-CoV-2 in any setting. Outcome measures included transmission rate, cycle threshold (Ct) values and viral load. We identified a rapid review by the University of Calgary that was the main source of our outcome data. Nine studies published following the rapid review were also identified and included.

In total, 35 studies were included in this review: one randomized controlled trial (RCT), one post-hoc analysis of an RCT, 13 prospective cohort studies, 16 retrospective cohort studies and four case control studies.

All studies reported a reduction in transmission of the B.1.1.7 (Alpha) variant from partial and fully vaccinated individuals. More recent evidence is uncertain on the effects of vaccination on transmission of the B.1.617.2 (Delta) variant. Overall, vaccine effectiveness in reducing transmission appears to increase with full vaccination, compared with partial vaccination. Most of the direct evidence is limited to transmission in household settings therefore, there is a gap in the evidence on risk of transmission in other settings. One UK study found protection against onward transmission waned within 3 months post second vaccination.

Early findings that focused on the alpha variant, showed a reduction in transmission from vaccinated people. There is limited evidence on the effectiveness of vaccination on transmission of the Delta variant, therefore alternative preventative measures to reduce transmission may still be required.

At various stages of the COVID-19 pandemic, face coverings have been recommended and encouraged as one of the interventions to reduce transmission of the SARS-CoV-2 virus. However, in the earlier stages of the pandemic, decisions on face coverings relied primarily on evidence based on other viral respiratory infections. More direct evidence on the use of face coverings with COVID-19 developed in tandem with the pandemic.

Health Technology Wales undertook an ultra-rapid review to inform national guidelines, the work assessed the evidence on the effectiveness of face coverings to reduce SARS-CoV-2 transmission. We also reviewed evidence on the efficacy of different types of face coverings.

We conducted a systematic literature search for evidence to address (i) the effectiveness of face coverings to reduce the spread of COVID-19 in the community, and (ii) the efficacy of different types of face coverings designed for use in community settings. We identified a rapid review in 2021 by Public Health England that closely aligned with our review questions. This provided the main source for identifying relevant studies, supplemented by a search for publications following their search date.

We identified two evidence reviews (including the Public Health England review) that examined the effectiveness of face coverings on reducing transmission of SARS-CoV-2; reporting on 31 and 39 studies, respectively. Two further primary studies were published after the two evidence review searches were included. Overall, the evidence suggested that face coverings may provide benefits in preventing SARS-CoV-2 transmission, although the higher-quality studies suggested that these benefits may be modest. Medical masks appeared to have higher efficacy than fabric masks, although the evidence was mixed.

At the time of this review, evidence on the effectiveness of face coverings remains limited and conclusions rely on low-quality sources of evidence with high risk of bias, although higher-quality evidence points to some benefit. Face coverings may play a role in preventing transmission of SARS-CoV-2, particularly as part of a bundle of other preventative measures.

Updating of health technology assessments (HTAs) is generally more efficient than starting again when new evidence emerges, but there is no clear guidance on how to do this. Health Technology Wales (HTW) has developed a re-assessment process to ensure that HTAs remain current and relevant to best serve the population and health and care providers in Wales.

HTW developed a standard operating procedure (SOP) to create a consistent approach to HTA re-assessment. HTW keep a record of stakeholders who contribute to a HTA and then send them a questionnaire to ascertain whether the research question is still relevant and if there have been any developments to the evidence since publication of the HTA. The input from these stakeholders is collated and taken to HTW’s Assessment Group to decide whether or not the HTA needs updating. If the Assessment Group decides that re-assessment of a HTA is warranted, HTW perform an updated literature search to inform the re-assessment.

The HTA re-assessment SOP developed by HTW was approved by the organization’s Assessment Group. At the time of writing this abstract, HTW sent questionnaires to stakeholders of three HTAs which had HTW guidance published three years ago, and were therefore due routine consideration for re-assessment as detailed in our SOP. HTW also received a request from a clinician for a more recent HTA to be considered for re-assessment as they believed the evidence-base had changed since original publication. These questionnaires have been collated and will be taken to an upcoming Assessment Group to decide whether HTW should proceed with the re-assessments.

HTW has developed a consistent process for HTA re-assessment, which ensures that HTAs done by HTW remain current and relevant to best serve the population and health and care providers in Wales. By utilizing expertise from HTA stakeholders and HTW Assessment Group members, an informed decision can be made as to whether a HTA warrants re-assessment after three years following publication or sooner if requested.

The COVID-19 pandemic has had a dramatic impact on the health and social care landscape, both in terms of service provision and citizen need. Responsive, evidence-based research is essential to develop and implement appropriate policies and practices that manage both the pandemic itself, and the impact COVID-19 has on other health and social care issues.

To address this, the Wales COVID-19 Evidence Centre (WCEC) was launched in 2021 with the aim of providing the best available, up-to-date, and relevant evidence to inform health and care decision making across Wales.

Funded by the Welsh Government, the WCEC comprises of a core team and several collaborating partner organizations, including Health Technology Wales, Wales Centre for Evidence-Based Care, Specialist Unit for Review Evidence Centre, SAIL Databank, Public Health Wales, Bangor Institute for Health & Medical Research in conjunction with Health and Care Economics Cymru, and the Public Health Wales Observatory. Over the last year, WCEC has developed its rapid review processes and methodology informed by best international practice and aims to provide around 50 reviews each year. WCEC works alongside various stakeholder groups from health and social care across Wales, and they form an integral part of the review process, from scoping to knowledge mobilization.

To date, the WCEC has produced reviews on a diverse range of COVID-19 topics, including transmission, vaccination uptake (barriers, facilitators and interventions), mental health and wellbeing, as well as face coverings and other preventative interventions. The topics have also covered a wide range of populations, from general public, to healthcare workers, to children. These reviews have been used to inform policy and decision-making, including the Welsh Government’s Chief Medical Officer 21-day COVID-19 reviews.

The WCEC has brought together multiple specialist centers with a diverse range of skills to produce timely reviews of the most up-to-date research to support decision makers across health and social care. These reviews have informed policy and decision-making across Wales.