Coronavirus

Trial will explore whether tests for contacts of infected people reduce the need for them to isolate

Daily testing of the contacts of people who test positive for Covid is to be trialled, the government has announced, in an effort to reduce the need for people to self-isolate unnecessarily.

People who test positive for Covid and their close contacts currently have to isolate for 10 days, but recent research has suggested compliance may be low. One study found that only about 50% of people who had Covid symptoms said they fully adhered to self-isolation.

The trial, which launches on Sunday and is led by Public Health England (PHE) and NHS test and trace, will explore whether the use of daily testing of close contacts could reduce the need for people to isolate.

“We know that isolating when you have been in contact with someone who has tested positive for Covid-19 is challenging, but it remains vitally important to stop the spread of infection,” said Prof Isabel Oliver, PHE’s national infection service director and the study lead. “This study will help to determine whether we can deploy daily testing for contacts to potentially reduce the need for self-isolation, while still ensuring that chains of transmission are stopped.

“Contacts of cases are at higher risk of infection, so testing them is a very effective way of preventing further spread. This study will play an important part of our evaluation of daily contact testing and how the approach to testing might evolve.”

The government’s Scientific Advisory Group for Emergencies (Sage) had previously noted the potential for daily testing.

“Modelling indicates that daily testing of contacts of confirmed cases of Covid-19 may offer a supplement or alternative to quarantine strategies. In some scenarios, daily testing offers a similar level of effectiveness to quarantine in reducing transmission,” the minutes of an 11 March Sage meeting note.

“The modelled impact is highly dependent on behavioural factors [in particular, levels of adherence for each approach], much of which is currently unknown and which would need careful consideration.”

The study will involve two types of Covid test: lateral flow and PCR tests. The former are faster and cheaper. People can take them themselves at home with results in 30 minutes. They are less accurate than PCR tests. Twice-weekly lateral flow tests are currently available to everyone in England for free.

The trial will offer a subset of people identified as a close contact of someone with Covid the chance to take daily lateral flow tests for a week rather than automatically self-isolate, provided they are over 18, not in full-time education, live in England, do not have Covid symptoms and their Covid-positive contact is not infected with certain variants.

If the tests are negative, the individual will not have to isolate on those days. PCR tests will be carried out at the start and end of the seven-day period, and if a lateral flow test is positive.

Prof John Ashton, a former regional director of public health and regional medical officer for the north-west of England, who is not involved in the study, said lateral flow tests were an important way of giving people agency.

“At this stage where the virus is circulating at very low levels, I am in favour of carrying out experiments,” he said, adding that there needed to be adequate support available, whether financial or otherwise, to enable people to isolate should they test positive.

The health secretary, Matt Hancock, welcomed the trial. “This new pilot could help shift the dial in our favour by offering a viable alternative to self-isolation for people who are contacts of positive Covid-19 cases, and one that would allow people to carry on going to work and living their lives,” he said.

“Alongside the phenomenal progress of our vaccination rollout, with over 48 million vaccines administered so far, rapid testing is allowing us to get back to doing the things we all love.”

Robert West, emeritus professor of health psychology at University College London and a participant in the behavioural science subgroup of Sage (SPI-B), raised concerns over the study, including that there may be too few Covid cases at present to draw strong conclusions about the relative merit of the daily testing approach, and that results from a trial where people can decline the option of daily testing may not be generalisable to a situation where daily testing is routine.

“From the limited information available, I would be very doubtful as to whether the trial will provide useful results,” he said.

But David Heymann, chair of the World Health Organization’s strategic and technical advisory group for infectious hazards and an epidemiologist with the London School of Hygiene and Tropical Medicine, praised the UK’s proactive attitude around studying the effectiveness of new strategies for outbreak control.

“If this strategy is proven effective it will likely lead to a more acceptable means of controlling Covid-19,” he said.

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