This is what can happen if lockdown eased too quickly

BY October last year, at least three-quarters of people living in the Brazilian city of Manaus were testing positive for Covid antibodies. The novel coronavirus had swept through the region’s population, leading to one of the highest infection rates in the world, partly as a result of Brazilian President Jair Bolsonaro’s denial that the pandemic posed a major threat.

The blood samples, reported in the Lancet, were explicit proof that 76 per cent of residents had been exposed to the virus – but it also led to an assumption they would be largely immune to a second wave.

Manaus was an interesting test case for those who advocated a herd immunity approach.

Hospitalisations for Covid had remained stable and fairly low from May to November, following the peak of the epidemic in April when authorities were forced to carve out mass graves to bury the dead.

It came as a shock therefore – 210,000 deaths later – when the number of patients being admitted to hospital with the disease suddenly started soaring again in January and, at first, no one knew why.

Had antibody prevalence been over-estimated? Was immunity waning already?

We know now that what was really driving the upsurge was a new mutant strain – P.1 – that was first detected in Manaus on January 12 but had begun circulating there in December.

By the end of January, 200 bodies a day were being interred in Manaus compared to the usual 40. Some hospitals ran out of oxygen, and intensive care units were overwhelmed.

Then, on January 29, three oil workers boarded a plane from Brazil to Aberdeen, via Paris and London.

They were employees of Bureau Veritas, a global company that provide services to the offshore industry, and had been working in Brazil since December 23.

All three had tested negative for coronavirus in the 72 hours prior to departure, a mandatory requirement for all international arrivals into the UK.

If they had landed at Heathrow any time from February 15 onwards, all three would have been whisked away into supervised hotel quarantine for 10 days before flying on to Scotland.

But in late January the “red list” country rule was not yet in operation and, instead, they flew on to Scotland, where they self-isolated on arrival.

On February 5, all three tested positive for coronavirus, with two subsequently admitted to hospital, though both have since recovered.

Genomic testing would later reveal their infections were caused by the P.1 variant, which had not previously been detected in the UK. They must have been incubating the virus at the time they boarded the plane from Brazil.

The good news is that, to date, there is no evidence the P.1 variant has escaped into the community.

More worrying, however, is that 34 passengers – more than one-third of those who shared their London to Aberdeen flight – were yet to be traced as of Wednesday (this has been blamed on invalid contact details, which suggests, somewhat bizarrely, that a very high number of air travellers are providing duff details to contact tracers).

Meanwhile, in England – where three P.1 infections were also confirmed last weekend – the search ended yesterday to identify a missing case.

Two of the three had been confirmed as members of the same South Gloucestershire household with recent travel to Brazil, but the third individual was unlinked – and potentially not self-isolating.

It is understood public health officials have now found the person and traced all of their contacts.

The confirmation of the P.1 variant in the UK this week has coincided with an alarming study into the Manaus outbreak by Imperial College London – although the researchers caution that its findings “should not be generalised to other epidemiological contexts” where the strain has been found.

So far, it has been detected in 25 countries, including Japan, Italy, South Korea, America, India, Germany, France and the Netherlands.

The ICL study found the proportion of Covid infections caused by the P.1 variant went from zero to 87% in the space of eight weeks.

They estimate it is 1.4 to 2.2 times more transmissible than the original Wuhan strain thanks to a “unique constellation of mutations”. For comparison, the UK ‘Kent’ variant is thought to be around 50% – 0.5 times – more infectious.

Its mutations include N501Y (which the Kent strain also shares, allowing it to spread more easily), but also one called E484K (shared by the South African variant) which has reshaped the spike protein and means antibodies are unable to bind to them as effectively.

This raises the prospect it could evade vaccines and also explains why herd immunity did not work in Manaus: people were being reinfected.

Dr Nuno Faria, reader in viral evolution at ICL and lead author of the study, told press on Tuesday: “If 100 people were infected in Manaus last year, somewhere between 25 and 61 of them are susceptible to reinfection with P.1.”

The study has not yet been peerreviewed and Professor Sharon Peacock, head of the UK’S genetic surveillance programme, stressed it was too soon to “speculate on vaccine efficacy”.

Pfizer and Moderna are already developing booster shots against the South African variant which would, hopefully, show similar effectiveness against the Brazil variant.

Nonetheless, the experience in

Manaus should serve as a warning against complacency. In the UK, where the Kent variant accounts for more than 85% of cases, vaccines are driving down deaths and serious illness and potentially even slowing transmission.

The risk of a P.1-type variant – whether imported or able to evolve domestically if we lift restrictions too quickly and allow infections to surge – is a bit like an athlete slowing down too close to the finish line, only to be overtaken.

And that would be a bitter blow indeed.

ANALYSIS The city of Manaus is the epicentre of the Brazil variant outbreak – and a warning of the worst-case scenario if we ease lockdown too quickly, writes Helen Mcardle