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Ninety-sixth SAGE meeting on COVI D-19, 14 October 2021.

(1 Post)
PippaZ Sat 23-Oct-21 14:04:24

Impact of potential Plan B mitigations considering the impact of the Delta variant and the behavioural response to reimposition of measures.
23. The proposed Plan B measures set out in the Government's autumn/winter plan are likely to be most effective when used in combination. Measures are not likely to be simply additive but to interact, resulting in a greater cumulative effect.
24. That effect is influenced by the context in which they are introduced, how they are introduced and by adherence. Measures have associated harms and potential for unequal impacts that should be considered prior to implementation.
25. There has been a decrease in self-reported precautionary behaviours such as wearing a face covering. Effective reintroduction of measures would require clear and positive public communications (providing sufficient time for implementation), setting out expected impacts as well as scope, exemptions and approach to enforcement.
26. Reintroduction of working from home guidance is likely to have the greatest individual impact on transmission out of the proposed measures. Impact would be dependent on effectiveness of communication and guidance, employer response, and the proportion of workers able to work from home who were not already doing so at the time of implementation. It was noted that “presenteeism” may become an increasing reason for spread in the workplace and that it will be important to communicate effectively to avoid this.
27. There is some evidence that vaccine certification may have a positive impact on vaccine uptake, particularly in younger age groups, but data are not directly comparable between countries which have used different approaches to certification. Introduction should consider vaccine effectiveness, evidence on waning immunity, and legal and ethical issues around equity, data security and interoperability. The range of settings involved is likely to affect both the potential impact on vaccine uptake and transmission. Public support is likely to influence effectiveness and is lower for approaches applied to wider ranges of settings.
28. Face coverings are expected to have some effect to reduce transmission through all routes by partially reducing emission of and exposure to aerosols and droplets carrying the virus, reducing transmission risk at both close proximity (even for short periods of time) and over longer range. Effectiveness is dependent on the quality of the covering, the fit and ensuring both the nose and mouth are covered. Mandating face coverings in some settings is likely to also have benefits for reducing transmission of other respiratory viruses.
29. There is no evidence that the fundamental mechanisms of transmission are different with the Delta variant, although it is more transmissible than the Alpha and other variants. It is unlikely that different mitigations are required, but there are some examples of large outbreaks occurring in settings with mitigations in place, highlighting the importance of ensuring measures are implemented rigorously and in combination following risk assessment of each mechanism of transmission.
30. As for other variants, household transmission, while reduced, continues to occur between vaccinated individuals infected with Delta. A significant proportion of transmission occurs in households and additional public guidance on mitigating this would be helpful. Transmission can occur through a number of routes, including through exposure to aerosols/droplets or contaminated surfaces. Although inhalation is a more likely route of transmission in shared indoor air or at close range, hand washing, and other environmental mitigations remain important. There is recent evidence of a correlation between hand swab positivity and transmission within households.
31. Other measures beyond those proposed as part of Plan B are available to mitigate the need for further measures over winter. Availability of asymptomatic and symptomatic testing for SARS-CoV-2 remains an important measure, as well as contact tracing and self-isolation.
32. SAGE advised that policy work on the potential reintroduction of measures should be undertaken now so that it can be ready for rapid deployment, stressing the importance of reintroducing measures in combination, supported by clear communication; consistent implementation that avoids creating barriers to adherence; and clear triggers for deployment.

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