Scientists warn ongoing measures needed to control resurgence in Covid cases

Documents released by the Scientific Advisory Group for Emergencies (Sage) on Monday state that as current measures are lifted, transmission will “almost certainly increase”, with modelling suggesting it is highly likely infections will peak at some point after Steps 3 and 4.

One paper from the Scientific Pandemic Influenza Group on Modelling, the Scientific Pandemic Insights Group on Behaviours (Spi-B) and Environmental Modelling Group (EMG), and dated April 22, says a package of “baseline” measures should be considered, as individual measures are likely to have limited impact.

The document also says: “There is significant risk in allowing prevalence to rise, even if hospitalisations and deaths are kept low by vaccination.

“If it were necessary to reduce prevalence to low levels again (e.g. VoC become more pathogenic for others previously less affected), then restrictive measures would be required for much longer.”

The scientists say another wave would be expected to occur even if the assumed baseline measures reduce transmission by 25%, but that it would be much higher without these.

As well as wearing face coverings, the baseline measures considered include symptomatic testing and isolation (following a positive test), contact isolation, certification to show negative testing or vaccination, and physical distancing.

On physical distancing, the document says: “Close range transmission [is] likely to be highest individual exposure risk, so explicit measures to address are likely to be beneficial.”

It also states: “Even beyond the point when all adults have been offered the vaccine, keeping some level of measures in place both through summer and beyond would significantly decrease ongoing transmission.

“It is notable that countries (e.g. New Zealand) that have near-zero Covid-19 have decided to retain some baseline measures (e.g. wearing of masks on public transport) to reduce the impact of occasional outbreaks.”

On the effectiveness of QR code check-in and collecting contact details the document suggests it is currently ad-hoc and quite limited due to data remaining on individuals’ phones and only a small proportion of people routinely using check-in.

Scientists warn: “It is highly likely that transmission will increase in autumn and winter.

“This may mean that the effectiveness of baseline measures may vary through the year, and they will have to be augmented to have the same impact.

They add: “Lifting restrictions may recreate the conditions for super-spreader events, both person driven (one highly infectious but possibly asymptomatic person going to multiple places) and setting-driven (nightclubs, religious events where crowding is experienced, low ventilation, loud activities etc).”

The document sets out a number of other measures that are also likely to be needed, such as vaccination, border controls, responses to variants of concern (VoC), and local reactive measures to hotspots and outbreaks.

In a document from a Sage meeting on April 22, the Government scientists say ongoing baseline measures and sustained long-term behavioural change “will be required to control a resurgence in infections”.

They say there are three main ways in which baseline measures can reduce transmission – reducing the likelihood that people who are infectious mix with others, for those potentially infectious people who are not isolated, reducing the likelihood that they enter higher risk settings or situations, and decreasing the transmission risk from a potentially infectious person in any given environment.

The most effective baseline measures, if adherence is good, are likely to be those which address the first of these objectives, the researchers say.

The document says: “As there is a move from rules to guidance and individual decision making, sustained behaviour change will also be required for measures to be most effective.”