World Records First Ever Double Covid Infection As Patients Test Positive For Two Different Variants

Two patients in Brazil have tested positive for more than one strain of coronavirus at the same time in what is believed to be the world's first double Covid infection.

Researchers at Feevale University made the discovery after swabbing 90 infected people in Rio Grande do Sul, southern Brazil.

One of the patients tested positive for two Brazilian strains which evolved separately in different states, known as P.1 and P.2.

P.1 has caused international alarm because it appears to be somewhat resistant to vaccines, which has led to Britain banning all travel from South America.

Another patient tested positive for P.2 and the B.1.91 strain, which first appeared in Sweden, at the same time.

Fernando Spilki, the lead researcher on the study, said he feared the co-infections would 'generate combinations and generate new variants even more quickly'.

Dr John McCauley, director of the Worldwide Influenza Centre at the Francis Crick Institute in London, told MailOnline it was possible for someone to get infected by two strains at the same time, which can happen with the flu.

He warned that, while unlikely, it was biologically possible the two strains could interfere with one another and swap genetic code.

'Getting one strain up a nostril and another up another nostril doesn't matter...but (the risk is) if they get to the back of the throat and then go into the same cell - then there's an opportunity for this to happen.'

Another senior scientist, who asked to remain anonymous, said it was possible the Brazilian scientists had contaminated their samples during sequencing, leading to incorrect results.

Brazil is in the middle of a devastating second wave of Covid, with more than 1,000 deaths a day, and the second highest fatality toll worldwide.

At least two variants have spawned there, which experts believe is due to such a high level of sustained transmission, and multiple others are in circulation.

Dr Julian Tang, a professor in respiratory sciences at the University of Leicester, said it was 'not uncommon' for two strains of a virus to infect the same person.

'It is perfectly possible for a child attending a primary school to get infected with one variant of Covid-19, and an older sibling to attend secondary school and get infected with a different Covid-19 variant - and for both children to bring their viruses home to infect each other - and their parents with both variants,' he told MailOnline.

What variants are causing panic around the world?

Kent variant

Real name: B.1.1.7

When was it discovered? The variant was first found in the South East of England and can be traced back to September 2020.

What mutations does it have? It has 23 mutations, some of which change the shape of the spike protein on its outside. The main mutation is known as N501Y. This appears to make it better able to stick to the cells inside the body and makes it more likely to cause infection and faster to spread.

Why is it causing worry? UK studies have shown it is between 50 and 70 per cent more infectious than the regular strain, which has made it harder to control. Preliminary studies also show it is about 30 per cent more deadly than previous versions.

How many people have caught it in the UK? It is the dominant strain in Britain and accounts for the majority of new cases.

Brazil variant

Real name: P.1

When was it discovered? In Tokyo, Japan, in four travellers arriving from Manaus, Brazil, on January 2.

What mutations does it have? P.1 has 17 mutations, three of which are particularly concerning to scientists.

Like the Kent variant, it also has the N501Y mutation which suggests it's more infectious and possibly more lethal.

It also has a spike alteration named E484K, which scientists believe may be associated with an ability to evade parts of the immune system called antibodies.

Researchers suspect this is the case because strains with this mutation have been shown to reinfect people who caught and beat older versions of Covid.

Another key mutation in the variant, named K417T, has the potential to 'possibly escape some antibodies', according to British experts.

This mutation is less well-studied and the ramifications of this are still being researched.

Why is it causing worry? There have been a number of proven cases of people catching this variant after beating older versions of the virus. It strongly suggests the variant can evade natural immunity and possibly even vaccines.

How many people have caught it in the UK? It's not. Public health officials and scientists randomly sample around 1 in 10 coronavirus cases in the UK and they have not yet reported any cases of the variant, but this doesn't rule it out completely.

South African variant

Real name: B.1.351

When was it discovered? Nelson Mandela Bay, in South Africa's Eastern Cape Province, in mid-December.

What mutations does it have? The South African variant carries 21 mutations, including E484K and N501Y.

Why is it causing worry? Those two mutations suggest it is more infectious than the older version of Covid and raise the possibility of antibody resistance. However, Sir Patrick Vallance has said there is no reason the South African or Brazilian strains would become dominant in the UK, because they don't have any evolutionary edge over the Kent strain currently plaguing the country, which is just as transmissible.

How many people have caught it in the UK? At least 77 Brits have been infected with this variant, though the number is likely to be far higher because PHE is only testing random positive samples.

Professor Lawrence Young, a virologist at the University of Warwick, said it was unlikely that two strains of Covid-19 could infect a cell at the same time.

'If one virus gets in it takes over that cell, and it's difficult for another to get in,' he told MailOnline.

He added changes in the virus were being driven by random mutations: 'It does mutate at a very very low rate and a lot of (its mutations are) in response to the low pressure that we put on it.'

He said it was through this mechanism that changes in the virus were occurring and new strains were evolving, and there was no proof that variants had emerged after swapping genes between different viruses.

Professor Keith Neal, an infectious diseases expert at the University of Nottingham, said if there's a lot of transmission 'you can pick up two different viruses around the same time'.

But he cautioned that when there is a predominant strain - such as the Kent version in large parts of the UK - people are only likely to catch this one.

Covid-19 has been evolving using mutations during the pandemic, which are triggered when the virus makes mistakes while making copies of itself.

The N501Y change, which makes the virus more infectious, is one example. It has occurred separately on the Kent, South African and Brazilian variants.

The variants have sparked fears the virus could mutate to get around immunity triggered by the vaccines, based on the original form identified in Wuhan, China.

But studies show that while the strains appear to make the current crop of vaccines less potent, the jabs are still enough to kill off the mutant variant.

Nonetheless, vaccine developers are already working on booster shots to ensure they are 'ahead of the curve' should a variant emerge that can dodge jab immunity.

The samples from patients were sequenced in a lab to confirm whether patients had been infected with the virus, with the results published as a pre-print, meaning they haven't been checked by other scientists.

It comes as health chiefs began door-to-door mass testing in parts of England today after 11 people tested positive for the South African variant of the virus.

In a desperate attempt to keep track of the mutated virus that experts fear could hamper the current crop of vaccines, health officials will visit homes in Woking in Surrey, Walsall in the West Midlands, as well as parts of London, Kent, Hertfordshire and Lancashire.

More than 80,000 over-16s will be targeted as part of the huge surveillance scheme and residents will be asked to take a test regardless of whether or not they have symptoms. Local health workers will go door-to-door, as well as police officers, firefighters and council workers.

As well as knocking on doors and asking residents to take tests there and then, extra mobile swabbing units will be deployed to all eight postcodes and home testing kits will be available to order online for residents to do themselves.

Public Health England has already spotted 105 cases of the 'B.1.351' South African variant since December 22, including at least 11 people — scattered across the eight areas receiving extra testing — who were struck down with the virus but had no history of international travel.

Health Secretary Matt Hancock said 'enhanced contact tracing' had been carried out to isolate the 11 patients' close contacts. There is currently no evidence that the variant causes more severe illness and early studies suggest the current crop of jabs are good enough to protect against it.