Government scientists have warned of a “developing situation” over people bringing coronavirus into the UK after travelling abroad and returning home without being tested.
People who travel overseas are required to quarantine for two weeks on their return unless they have visited a country on the official list of nations considered low risk for Covid-19.
But poor compliance with quarantine and the lack of testing at airports and other borders mean infected travellers can spread the virus when they get home, even if they test positive and self-isolate later.
Experts on the disease modelling subgroup of Sage, the government’s scientific advisory committee, warned that while imported infections were a small proportion of UK cases, they still posed a threat.
In a statement dated 2 September, but released in a bundle of Sage documents on Friday, the expert group concede that testing at borders was unlikely to prevent returning travellers from starting fresh outbreaks. But the measures could provide valuable surveillance for inbound infection and help remind people of the need to quarantine, they say.
According to the report, the modelling operational subgroup, known as SPI-M-O [the scientific pandemic influenza group on modelling], is “concerned about the developing situation around the importation of infection from people arriving in the UK”. The document goes on to warn that “whilst this is a small minority of infections in the UK it poses a threat”.
Speaking to MPs on the parliamentary science and technology committee this week, Lord Bethell, the minister for innovation, said work on testing arriving travellers was ongoing with the Department of Transport, airlines and airports, but that the quarantine advice from Prof Chris Whitty, England’s chief medical officer, was clear. “We’ve already had very tough outcomes from people coming into the country bringing disease with them, and we have to rely on people complying with quarantine, and the evidence suggests that that is a very difficult thing to rely upon,” Bethell said.
There have been calls from the travel industry and some Tory MPs to bring in airport testing and reduce quarantine times to allow more travel for holidays and business.
In the summer, science advisers realised that thousands of cases, mostly from France and Spain, had been imported into the UK in February and March, seeding outbreaks around the country.
“Although testing at borders is unlikely to have significant impact on importation rates, it would provide important epidemiological surveillance data and potentially reduce onwards transmission if it results in higher adherence to quarantine periods and activating onwards contact tracing,” the statement adds.
Public Health England said it did not publish numbers of likely imported cases.
In another document released on Friday, the minutes of a Sage meeting on 3 September, advisors cautioned that the proportion of people with antibodies against coronavirus, about 6% nationally, was unlikely to reduce the impact of a winter resurgence.
With the second wave building, the committee called for public-health messaging to explain that people are at risk of getting Covid-19 twice and must still isolate even if they have had the virus before.
Further minutes from a Sage meeting on 27 August called for caution over mass testing. The advisors said the approach was mostly likely to work in well-defined, high-risk settings, such as care homes and meat processing plants, where large outbreaks could be caught early. But mass testing, through pooled saliva samples, could backfire in areas with little virus around because false positive rates could reduce public confidence in testing.