Coronavirus (COVID-19) vaccine certification: evidence paper update

6. Alternative mitigation measures

A number of baseline measures are still in place in Scotland including:

• Wearing face coverings in public indoor settings including public transport.
• Providing your contact details when you go to places like pubs, cafes and restaurants.
• International travel – testing and quarantine requirements^[88].

In addition guidance is still in place recommending working from home if possible.

In their latest paper on transmission, environmental and behavioural mitigation strategies, EMG and NERVTAG report that Mitigations need to be applied together; enhancing one measure such as ventilation cannot fully compensate for the removal of other measures, especially if they address different transmission routes. There are no silver bullets. (high confidence).

They go on to identify the environmental and behavioural interventions that are likely to be most effective as:

• Ensuring good airflow by interacting outdoors and improving poor indoor ventilation can mitigate airborne transmission (high confidence).
• Maintaining a greater distance between people can mitigate direct exposure to aerosols and droplets at close range where they are more concentrated (high confidence). Consideration and avoidance of small spaces or close interactions remains important. It is likely to be beneficial to reiterate the importance of physical distancing even in settings where restrictions on numbers of people have been removed.
• Promoting high levels of wearing face coverings or face masks can potentially reduce transmission through all transmission routes, especially via close range and long-range airborne transmission (high confidence).
• Ensuring good hand and respiratory hygiene, limiting face touching and using face coverings are likely to reduce the small risks of fomite transmission. As transmission via surfaces is most likely to occur in a short time period following contamination, hand and respiratory hygiene is likely to be more effective than enhanced cleaning in most settings (medium confidence).^[89]

This mirrors the advice included in the SPI-M/SPI-B/EMG review of the UK Plan B which advises^[90]

• Face coverings are likely to reduce transmission and are likely to be more effective when they are good quality and well-fitting [High confidence].
• Mandating the use of face coverings in appropriate situations is likely to increase usage [High confidence].
• Increasing vaccine uptake (including boosters) continues to be the most important measure to mitigate the health impacts of the SARS-CoV-2 epidemic in the UK.
• Other measures are available - for example encouraging wider use of rapid antigen testing in workplaces and the community, and ensuring self-isolation of those who test positive by providing sufficient support [High confidence].

SAGE also emphasise the importance of testing when symptomatic and staying at home with flu like symptoms^[91].

The Juniper consortium analyse other measures that could be used during a high rise in infections, and considered that some will take longer (but have a lasting impact) which are listed first below, whilst other measures are more immediate (but less sustainable) listed last^[92].

1. Improved ventilation in schools and workplaces

2. Improved public awareness

3. Boosters and increased vaccine uptake

4. Test, Trace and Isolate (TTI) (test and protect in Scotland)

5. Changes to restrictions and potential lockdowns

6. Antivirals 2 and pharmaceuticals.

7. Travel restrictions.

The current baseline measures and all those suggested by others aim to reduce the likelihood of infectious people mixing with others and infecting them. In a context where social contacts are rising as shown by recent results of the Scottish Contact survey^[93], reducing the risk from social interaction is essential.

We know that vaccinated individuals can still transmit the virus but we also know that vaccinated individuals are less likely to become infected or to become seriously ill and require hospitalisation.

SAGE noted in April 2021 that:

there are three main ways in which baseline measures can reduce transmission (from most to least effective) ^[94]:

1. Reducing the likelihood that people who are infectious mix with others.

The most effective baseline measures are likely to be ones which reduce infected people mixing, such as an effective test, trace and isolation system (high confidence)^[95].

2. For those potentially infectious people who are not isolated, reducing the likelihood that they enter higher risk settings or situations

EMG SPI-M advises that the next most effective baseline measures aim to eliminate or substitute some of the higher risk situations where transmission could occur. This could be by using a certification scheme based on negative testing, vaccination, or proof of prior infection^[96]. Other important ways would be by minimising the frequency and duration of exposure such as encouraging outdoor interactions, working from home, and generally reducing the number, size, and duration of interactions^[97].

3. Decreasing the transmission risk from a potentially infectious person in any given environment^{[98] [99]}

EMG SPI-M advises that to decrease the risk of transmission from an infectious person the following non pharmaceutical interventions (NPIs) should be considered: ^[100]

• Physical distancing (to reduce risk from respiratory droplets and short-range aerosols)^{[101] [102] [103]}
• Ventilation (to reduce risk from long duration exposure and far-fields aerosol transmission)^{[104] [105] [106]}
• Face coverings (to reduce emission of virus and exposure to droplets and larger aerosols)^[107]. Other forms of barriers (e.g. Perspex screens) may provide some protection from droplets in some circumstances though consideration needs to be given to airflows, as in some cases they may increase risk of aerosol transmission.
• Hand hygiene and surface cleaning (to reduce risk from fomites)^[108].

The 4 harms approach aims to develop the right package of measures that draws on the advice above but limits impacts on individual rights and broader societal or economic harms.

We already have in place measures such as vaccination and boosters, testing and isolation, mask wearing and hand hygiene. These address the first and third groups of mitigations and restrictions set out by SAGE. However, to address the second we have a choice of limiting social contacts by closing venues, limiting group sizes and advising people not to meet others or we can enable people to meet up in a lower risk way by using certification to reduce the risk that an infectious person will be present in a higher risk setting.

The vaccine certification scheme as proposed for Scotland is targeted towards higher risk settings or events and will be used in conjunction with the NPIs listed above^[109] to further enhance the overall preventative impact. As part of this package of mitigation measures, a vaccine certification scheme should ensure that only fully vaccinated individuals are present at these events reducing the risk of infection and severe illness leading to hospitalisation amongst the attendees.

SAGE considered with a medium confidence that a certification scheme could potentially have medium effectiveness^[110]. However they also warned that "certificates should also not be used to replace other measures to protect high-risk individuals"^[111].

Notably SAGE has suggested that "the prevalence of infection in the community will have an important impact on the level of risk and effectiveness of certification which may be very effective when prevalence is low, but less effective at high prevalence"^[112]