Omicron Bristol: More cases could be undetected due to low monitoring of PCR test results

Fewer than one in six PCR tests in Bristol checked for new variants
A coronavirus test kit is passed through a car window at a temporary testing centre at The MallA coronavirus test kit is passed through a car window at a temporary testing centre at The Mall
A coronavirus test kit is passed through a car window at a temporary testing centre at The Mall

More cases of the Omicron variant in Bristol could be undetected because a large proportion of PCR tests in the city are not being tested for the variant.

Today (December 8), Mayor Marvin Rees revealed there had been a confirmed case of the variant in the city.

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It is the first and only report of a case after the UK Health Security Agency (UKHSA) stopped publishing local authority-level figures last week.

However, patchy monitoring, particularly in the South West, and a time lag in the data means scientists have been left believing the variant of coronavirus is more widespread nationally than reported.

Monitoring for suspected cases of a variant, including Omicron, can be done through a check on a positive PCR test to see if the coronavirus S-gene is detectable. If it is not, the case is a suspected variant.

But S-gene testing ‘varies by geography with lower coverage since July 2021 in local authorities in the south-west of England’, the UKHSA said in an report on Friday.

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Figures supplied by UKHSA showed that in areas like Hartlepool, as much as 72 per cent of tests were checked for the S-gene, while in Bristol that proportion dropped to 16 per cent - the equivalent of fewer than one in six.

Across England, the proportion is 30 to 35 per cent.

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On Monday, Health Minister Sajid Javid told the Commons new testing methods were being brought in to detect suspected Omicron cases, adding all testing centres would be able to pick it up ‘very soon’.

Another, and more accurate, way of testing cases for Omicron is through genome sequencing of PCR test - but this can take up to a week.

Speaking to the Guardian, Dr Nicholas Davies, of the London School of Hygiene and Tropical Medicine, said it was likely there were more Omicron cases than those detected nationally.

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He said: “It is almost certainly more widespread. Even if Omicron wasn’t growing in frequency, cases take time to detect and S-gene coverage is not complete.”

Today, with the rise in confirmed Omicron cases to 333, Boris Johnson is said to be considering a move to Plan B of the Government’s strategy for dealing with Covid this winter.

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It would see the introduction of COVID vaccine passports and a return to the work from home order for millions of people.

Mr Johnson has previously told ministers that the Omicron variant appeared to be more transmissible than the Delta variant.

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In Bristol, the city’s director for public health, Christina Gray, urged people to take ‘preventative and protective measures’ to stop the spread of Omicron in the city.

She reminded people to wear a face covering and take lateral flow tests before attending gatherings.

She added: “Every action, however small, makes a difference. We will keep you up to date with any further information or action.”

While in relation to testing for the new variant, Mayor Marvin Rees told a press conference that the council had to ‘work with the data as we have it’.

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He added: “I would say we work very closely with community development workers across the city as well so where those national tools are not necessarily able to give us the full picture we do have our frontline resources of intelligence.”

A spokesperson for the UKHSA said local authority level figures on confirmed Omicron cases would be published later this week.

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