All about the variants of the coronavirus: Omicron, Deltacron, Delta...

 Several variants (Alpha, Delta...) of the SARS-CoV-2 coronavirus have appeared since the beginning of the pandemic. Now, in France, it is the Omicron variant that is in the majority. How many cases? How effective are vaccines against this new variant?

Many variants of SARS-CoV-2 are circulating around the world. Some are referred to as 'variants of concern' (VOCs) or 'variants to be monitored' (VOI) because their impact (transmissibility, contagiousness, potential immune escape) justifies the implementation of special monitoring and specific management measures. Other variants remain classified as 'under evaluation', in the absence of virological, epidemiological, or clinical evidence in favour of a public health impact in France. In France, the Omicron variant became the majority only one month after the detection of the first case in metropolitan France.

The new variant "Deltacron", what is it?

The Delta and Omicron variants are the two strains that are currently circulating very actively in many countries. What if they combined? This is what a Cypriot researcher fears: he claims to have discovered a new strain of the coronavirus that combines Delta and Omicron, as reported by articles in the Cypriot press including the Cyprus Mail, taken up by the Bloomberg News agency. Leondios Kostrikis, professor of biological sciences at the University of Cyprus and head of the Laboratory of Biotechnology and Molecular Virology, says that the "Deltacron" strain, as he has nicknamed it, has already caused at least 25 cases on the island of Cyprus, where the incidence rate of COVID-19 cases is considered the highest in Europe.

Its particularity? The genetic signature of the Omicron variant and the genomes of the Delta variant. "There are currently Omicron and Delta co-infections and we have found this strain which is a combination of both," Said Leondios Kostrikis in an interview with Sigma TV. "We will see if this strain is more pathological or more contagious or if it will prevail over Delta and Omicron," he added. Not without estimating from a personal point of view that this possible new strain will be replaced by Omicron, much more contagious than other strains of SARS-CoV-2. It should be noted that the discovery of this new mutation is awaiting official confirmation since samples have been sent to the GISAID device of the Institut Pasteur for analysis.

The role of this international database is to list all the observed changes and mutations of Covid-19, which are subsequently made available to the global scientific community. The presence of "Deltacron" was updated following analyses of samples taken from both the general population and hospitalized patients. The results showed that its frequency is higher in patients hospitalized due to Covid-19 compared to non-hospitalized patients, which could mean that there is a correlation between Deltacron and hospitalizations. But other details are all the more expected on this subject as the analysis of the genetic sequences of the supposed 25 cases has led some scientists to pronounce themselves for a "false alarm".

The newspaper Libération reveals that the hypothesis of improper handling in a laboratory is evoked on Twitter by some scientists who have had access to Gisaid. This is the case of Tom Peacock, virologist at Imperial College London who explains that "the Cypriot Deltacron sequences seem to be quite clearly a contamination, they do not group on a phylogenetic tree". It would therefore be rather a "mixture" between several laboratory samples. The latter adds that "true recombinations appear a few weeks or even months after the simultaneous circulation of several variants. Omicron has only been circulating for a little over two weeks, I doubt that there could have already been recombinations... So cases to follow.

Variant Omicron (B.1.1.529): symptoms, severity...

This new variant of the coronavirus was detected on November 25 in South Africa, the African country officially most affected by the pandemic. Named 'Omicron' by the WHO (B.1.1.529), it has an extremely high number of mutations, according to South African scientists: no less than thirty, while the Delta variant has only two. This variant is now the majority among Covid-19 infections in France, two months after its appearance in metropolitan France.

What are the symptoms of the Omicron variant?

According to data collected by Public Health France, the most frequent symptoms that appear after Covid-19 contamination are: 

• cough;
• fatigue;
• fever;
• Congestion or runny nose. 

Cases of nausea, vomiting, shortness of breath, and diarrhea have also been reported, but to a lesser extent. During the weekly update of January 6 of Public Health France, the loss of smell and taste is cited by only 10% of the 338 people interviewed by Public Health France.

In France, more than half of covid-19 deaths in hospitals are now linked to this variant

Between 17 and 23 January 2022, the Directorate of Research, Studies, Evaluation, and Statistics (Drees) estimates that the Omicron variant concerns 57% of deaths occurring in hospitals with Covid-19.

The results, published on Friday, Jan. 28, and updated weekly, also indicate that Omicron is responsible for 99 percent of positive PCR tests, 88 percent of conventional hospital admissions, and 79 percent of critical care admissions.

"The lower representation of the Omicron variant in hospitalized people than in those who tested positive therefore remains, even if this difference in prevalence is decreasing week after week," reports Drees. It would be the fact of the 'temporality of these events (which) differs since infections precede hospitalizations by about a week, themselves preceding deaths by about a week'.

A lower hospitalization rate with the Omicron variant than with Delta

According to a study published on January 10, 2022, by the Assistance Publique-hôpitaux de Paris (AP-HP), the probability of using critical care is "three times higher in patients infected with the Delta variant than with the Omicron variant". The AP-HP studied the share of the Delta variant and the Omicron variant in new patients hospitalized in its departments for Covid-19 between December 1, 2021, and January 4, 2022, in critical care and conventional hospitalization.

• "On average over the last week of 2021, about 19% of daily entrants with Omicron in critical care and 54% in conventional hospitalization," notes the AP-HP. 
• Conventional hospitalizations that correspond to stays of less than one day represent '19% of stays for incoming patients infected with Delta and 43% for incoming patients infected with Omicron'.

According to two British studies published on December 22, the risk of hospitalization related to an infection with the Omicron variant is 70% lower than during infection with the Delta variant.

Their results also showed that the Omicron variant would be less dangerous for the elderly than the Delta variant. "First of all, more of them have made their recall. But also for anatomical reasons. The Hong Kong researchers showed that with the Delta variant we had a lot of variants and viruses that went down into the lungs and it makes serious forms. While with Omicron it goes down less into the lungs, there are fewer serious forms," explained Dr. Damien Mascret on the set of France 2 on December 23.

Is the booster dose needed to protect against the Omicron variant?

In an opinion published on 16 December 2021, the Scientific Council confirms that a booster dose of vaccine would increase vaccine efficacy against Covid-19 and the development of a severe form of the disease. The booster dose (3rd dose) restores an immune response to the Omicron variant. It protects, probably at a good level, against the occurrence of severe and severe forms, but only partially protects against infection with the Omicron variant. According to the researchers, vaccine efficacy would remain at 70% after a booster dose.  

Getting out of the pandemic phase?

On Tuesday 11 January, the European Medicines Agency estimated that Omicron would transform Covid-19 into an endemic disease. From now on, we will have to learn to live with it.

"Nobody knows exactly when we will be at the end of the tunnel, but we will get there," said Marco Cavaleri, head of vaccine strategy at the Amsterdam-based European Medicines Agency (EMA). "With the increase in immunity in the population – and with Omicron, there will be a lot of natural immunity in addition to vaccination – we will move quickly towards a scenario that will be closer to endemicity." This is encouraging news that should not make us forget that the world is still in a pandemic.

A higher reinfection rate for the Omicron variant?

WHO Director-General Tedros Adhanom Ghebreyesus had announced that the reinfection rate of the Omicron variant would be much higher than other variants of Covid-19. "Preliminary data from South Africa suggest a higher risk of reinfection with Omicron, but more data are needed to draw firmer conclusions.

A data confirmed by the Scientific Council (opinion published on December 16, 2021): 'The transmission is significantly increased compared to the Delta variant.'

What is known about the Subvariant of Omicron, BA.2, detected in France?

The BA.2 sublineage of the Omicron variant has been detected in several countries, including France. Already the majority in India and Denmark, it has several mutations that could modify the characteristics of the virus. Most of them are found in the Spike protein, the key to the virus' entry into cells. 

"We know neither its origin, nor its virulence, nor its ability to escape immunity, including that conferred by Omicron. On the other hand, it seems to be more contagious," explained Antoine Flahaut, epidemiologist and director of the Institute of Global Health at the University of Geneva.

In France, in mid-January, only about fifteen cases of BA.2 subvariants have been sequenced for the moment. The authorities remain cautious: the subvariant BA.2 'corresponds to the characteristics we know of Omicron (...) It does not change the situation," assured the Minister of Health, Olivier Véran, Thursday, January 20. For its part, the WHO confirms to CheckNews "a trend of increase in BA.2 in recent weeks" and says "monitor the progression of BA.2 and its possible implications".

Effectiveness of vaccines against Omicron: what data are available?

In a new risk analysis of Covid-19 variants published on Friday 7 January, Santé Publique, France reported on the available data on the effectiveness of vaccines against the Omicron variant. 'Vaccine efficacy against infection (37 to 86%), hospitalization (70 to 88%), and severe forms (98%) appear to be maintained against Omicron after administration of a booster dose. Preliminary analyses conclude that Omicron has a reduced risk of hospitalization compared to other variants (up to 81%).' The agency recalls that these data should be interpreted with caution because cases of Omicron infection are still mostly identified in a young population, which is, therefore, less at risk. 

According to a study conducted by the Institut Pasteur and published on December 20, 2021, the Omicron variant would be resistant to the antibodies of a person who received his complete vaccination regimen five months ago with the Pfizer or AstraZeneca vaccine. Scientists find that blood from patients who have had COVID-19, collected up to 12 months after symptoms, as well as from people who have received both doses of the Pfizer vaccine or the AstraZeneca vaccine, almost no longer neutralize the Omicron variant, five months after vaccination. On the other hand, the sera of individuals who received the 3rd dose of Pfizer booster, analyzed one month after injection, remain effective against Omicron', reads the statement.

A few days later, it is Danish researchers who provide more details about the higher ability of the Omicron variant to circumvent the immunity of vaccinated people compared to the Delta variant. By surveying nearly 12,000 Danish households, the researchers found that Omicron was 2.7 to 3.7 times more infectious than the Delta variant is fully vaccinated Danes. This variant would therefore spread mainly faster because it better escapes the immunity obtained through vaccines.

In this study published in the journal "medRxiv" (a version of a scientific article that has not yet been validated by peers), and relayed by the Reuters agency, the researchers say that Omicron is not so much characterized by greater transmissibility, but by a greater ability to "escape" vaccine immunity. "Our results confirm that the rapid spread of the Omicron variant can mainly be attributed to immune evasion rather than an inherent increase in basic transmissibility," they say. Their study also shows that the effectiveness of the vaccine was reduced to about 40% against symptoms and 80% against a severe form of the disease when it came to the Omicron variant.

It also found that people who received a booster dose are less likely to transmit the virus, regardless of the variant, than people who were not vaccinated.

Finally, although more transmissible, Omicron seems to induce a less serious disease, ISS technical director Tyra Grove Krause told local media. "While Omicron will still be able to put pressure on our health care system, all indications are that it is milder than the Delta variant," she said, adding that the risk of being hospitalized with Omicron was halved compared to the Delta variant. "Maybe that's what will get us out of the pandemic so that it becomes the latest wave of COVID-19," she concludes.

Variant Omicron: are laboratories developing new vaccines?

Since the discovery, at the end of November, of the variant 'Omicron', it is the swing of combat on the side of the laboratories. Contacted by BFMTV, the Pfizer-BioNTech laboratory had explained that it was waiting for complete data from South African analysis laboratories before deciding on the possibility of developing a new vaccine.

For its part, "Moderna will rapidly develop a vaccine candidate for a booster dose specific to the Omicron variant," the U.S. company said in a statement on November 26. This announcement is part of a strategy to work on specific recall doses for variants of concern, according to the laboratory. "From the beginning, we have said that to fight the pandemic, it is imperative to be proactive in the face of the evolution of the virus," said Moderna boss Stéphane Bancel, quoted in the statement.

Oxford and AstraZeneca also say they can develop a new serum "very quickly", especially against the Omicron variant. In a statement, AstraZeneca also said it has "developed, in close collaboration with the University of Oxford, a vaccine platform that allows us to respond quickly to new variants that may appear." The British pharmaceutical company announced that it was "already conducting research in places where the variant has been identified".

Despite some claims widely relayed on social networks, variants are not created by vaccines. It is enough to take the example of the British variant that spread long before the vaccination campaign in the United Kingdom began, recalls Inserm.

Delta variant: contagion, diffusion, dangerousness?

The Delta variant was first identified in the fall of 2020, in the Nagpur region of India. To date, all the countries of Europe are confronted with it. According to the latest GISAID data, the majority of B.1.617 cases are identified in India, the United Kingdom, the United States, Germany and Singapore.

This lineage includes three sublineages, characterized by the L452R and P681R mutations: 

• B.1.617.1 (Kappa, VOI), 
• B.1.617.2 (Delta, VOC), the most frequent in France,  
• and B.1.617.3.

What are the differences between the three main Indian variants?

Each of the Indian variants involves a different risk, according to the Scientific Council (opinion of 24 May 2021):

Subline B.1.617.2 (Delta variant), which does not have the E484Q mutation (contrary to what was initially announced), is the most frequently detected lineage in France and Europe. Note that it also has additional specific mutations that can give it a superior transmissibility advantage to the other two lineages (L452R associated with T478K in the absence of E484Q mutation). It has been classified as VOC since May 12 by the WHO.

Subline B.1.617.1, (Kappa variant) which also has the combination of the two mutations, was detected in Europe and France, but at a low frequency compared to lineage B.1.617.2. Of the three viruses, it is the one that has the largest antigenic difference compared to the historical strain 'Wuhan' and therefore a risk of immune escape. It is classified as VOI. 

Subline B.1.617.3, which exhibits the combination of the L452R (which may be associated with an increase in virus transmissibility) and E484Q (responsible for post-infectious and post-vaccine partial immune escape) mutations, has spread very little in and out of India.

The Delta variant '40 to 60% more transmissible' than the Alpha variant

'This variant is characterized by increased competitiveness compared to other variants, including the Alpha variant. It is more transmissible than historical viruses (about 2 times more) and the VOC Alpha (about 40 to 60% more transmissible), Beta (about 60%) and Gamma (about 30%)', indicated Public Health France is a risk analysis published on July 28. And before adding: "Among the possible factors that may explain this increase in Delta's transmissibility, several different data sources indicate an increase in viral load in the nasopharynx in infected people compared to Alpha and other reference viral strains."

'A recent study conducted on a small number of people suggests a shortening of the Delta generational interval compared to the reference strains (4 days versus 6). Data from the UK, Canada, and Singapore indicate an increased risk of hospitalization and severe forms related to this variant compared to VOC Alpha and other reference strains," the organization said.

This variant is characterized by increased competitiveness compared to other variants, including the VOC Alpha. It is more transmissible than historical viruses (about 2 times more) and that THE VOC Alpha (about 40 to 60% more transmissible), Beta (about 60%), and Gamma (about 30%), confirms the risk analysis of Public Health France (August 25).

"The Delta variant is so contagious that it crushes the competition between variants, there is none that has managed to supplant it," explained Yannick Simonin, virologist specializing in emerging viruses, interviewed by Ouest France, October 18, 2021.

Are vaccines effective against the Delta variant?

The effectiveness of mRNA vaccines (Moderna and Pfizer/BioNTech) and Vaxzevria® vaccine (AstraZeneca) on the prevention of severe forms of Covid-19 is established. However, "vaccines save lives, but they do not completely prevent the transmission of Covid-19," said boss Tedros Adhanom Ghebreyesus on Wednesday 24 November.

Since August, the Pfizer-BioNTech laboratory has been working on an updated version of its vaccine that targets the peak protein of the Delta variant, reports BFMTV: "We took measures months ago to be able to adapt the mRNA vaccine within 6 weeks and ship the first batches within 100 days in case of the variant that escapes immunity,  says the Pfizer spokesman. To this end, the companies have begun clinical trials with alpha and Delta variant-specific vaccines to collect safety and tolerability data that can be provided to regulators as part of baseline studies if a specific vaccine is needed."

Having been infected with the coronavirus before being vaccinated would guarantee better protection against variants

Researchers at Imperial College London (study published on April 30 in the journal Science) had compared the immunity of patients who had contracted Covid-19 in the nine months before the injection, and the immunity of patients who had never contracted Covid-19, after administration of a single dose of vaccine. 

Their conclusions? Patients who have already had Covid-19 have significantly improved protection against the English and South African variants after a single dose of the mRNA vaccine. The scientists found that after the first dose of vaccine, a previous infection was associated with an enhanced response of T cells, B cells, and neutralizing antibodies, which could provide effective protection against SARS-CoV-2, as well as against the Kent and South African variants. However, since individuals contracted a moderate form of covid-19 before the first dose of vaccine, the antibody response was much less important vis-à-vis the English or South African variant.

Conversely, in patients who have never had Covid-19, the immune response is less after the first dose of vaccine, potentially making them more at risk of being infected with a variant. The data collected indicate that 90% of vaccinated people who have not previously been infected with the coronavirus have 'not developed detectable neutralizing antibodies against the English variant B.1.1.7 (after the first vaccine injection)'. This observation underlines the importance of deploying second doses of messenger RNA vaccine.

"Our study is reassuring and a warning. We show that current vaccines offer some protection against variants of concern. However, people who have only received the first cycle of a double-dose vaccine have a more attenuated immune response," warns Professor Áine McKnight, of the Queen Mary University of London.

Delta variant has reduced the effectiveness of vaccines against disease transmission to 40%, warns WHO

The Highly Contagious Delta variant has reduced the effectiveness of vaccines against the transmission of Covid-19 to 40%, the head of the World Health Organization (WHO) announced on Wednesday (November 24th). At a press briefing, Tedros Adhanom Ghebreyesus called on people to continue wearing masks and other barrier measures. 

"There is evidence to suggest that before the arrival of the Delta variant, vaccines reduced transmission by about 60%. With the Delta, it dropped to 40 percent," he said. "In many countries and communities, we are concerned that there is this misconception that vaccines have ended the pandemic and that people who are vaccinated no longer need to take further precautions."

What protective measures against omicron and Delta variants?

In order to protect against the Delta variant and other variants of the coronavirus, it is important to maintain barrier gestures and respect the protocol if you are considered a contact case.

What to do when you are a contact case, but already vaccinated?

If a person has a complete vaccination schedule and is not considered immunocompromised, there is no obligation to self-isolate. On the other hand, the contact case person must respect certain health rules to break the chains of transmission of Covid-19:

• immediately perform a screening test (RT-PCR or antigen test);
• inform the people we have met within 48 hours after meeting the sick person and recommend that they limit their social and family contacts;
• respect barrier gestures for 1 week after the last contact with the patient and in particular:
• limit social interactions, especially in establishments open to the public were wearing a mask is not possible;
• avoid contact with people at risk of severe illness, even if they are vaccinated;
• wear a category 1 mask in public spaces;
• if you live with a person who tests positive: wear a mask at home;
• carry out self-monitoring of temperature and the possible onset of symptoms, with immediate screening in case of symptoms, regardless of age;
• Perform a second self-test on Day 2 and Day 4 after the last contact with the positive person.

What to do when you are a contact case and you are not vaccinated?

If the contact case has an incomplete vaccination schedule or if he is immunocompromised it will be necessary to immediately carry out a screening test, RT-PCR, or antigenic (for children under 6 years, a salivary sample may be taken if the nasopharyngeal swab is difficult or impossible). 

• if the test is positive, the person becomes a confirmed case of Covid-19;
• If the screening test is negative, it is necessary to respect isolation at the home of 7 days, from the date of the last contact at risk with the person positive for Covid-19. 

How long should I self-isolate if I am positive for Covid-19?

Faced with the extremely active circulation of the Omicron variant and therefore the fear of disorganization of society, the government has set a new isolation deadline for patients and contact cases regardless of the variant. In order to limit the circulation of the virus as much as possible, the Ministry of Health recommends early isolation.

From 3 January 2022, all people with a complete covid-19 positive vaccination schedule (symptoms or not) must remain isolated for 7 days.

However, after 5 days, the positive person can be released from isolation under two conditions:

• - if it performs an antigenic test or RT-PCR and it is negative;
• - if she has had no clinical signs of infection since 48.

For anyone with an incomplete vaccination schedule or if they are not vaccinated, isolation is 10 days (full) after the date of onset of the signs or the date of collection of the positive test. Nevertheless, after 7 days, the positive person can be released from isolation under two conditions:

• she performs an antigen test or RTPCR and it is negative
• she has had no clinical signs of infection for 48 hours

If the test is positive or the person does not perform a test, isolation is 10 days.

'Contact persons at risk and persons suspected or confirmed to have been infected by a variant should be monitored more closely. Home visits by nurses are systematically offered and the people concerned whose personal situation suggests a high risk of spread must be systematically offered a specific offer of accommodation, "says the Minister of Health.

What behavior to adopt at the end of isolation?

For a positive person who had symptoms:

- In case of temperature on the 7th day, it is advisable to wait another 48 hours after the disappearance of the fever to finish its isolation.

- If you have difficulty breathing, you should call 15 immediately (or 114 for people who are deaf or hard of hearing).

For a positive person who did not have symptoms: 

- If no symptoms appear after 7 days, the isolation ends;

- If symptoms persist or appear after 7 days, the person contacts his doctor. In case of temperature (fever) on the 7th day, the person isolates himself for another 48 hours after the fever has disappeared.

For a person contact cases immunocompromised or with an incomplete vaccination schedule, in case of temperature on the 7th day, it is advisable to wait another 48 hours after the disappearance of the fever to complete its isolation.

At the end of the isolation period, everyone must again respect barrier gestures, such as wearing a mask and physical distancing, and avoid gatherings and contact with vulnerable people for a week.

Reminder: what is a variant?

By definition, viruses mutate constantly to adapt to the hosts they contaminate. The more viruses spread, the more they must mutate in order to always remain 'efficient'. But when viruses multiply in cells, their 'copying' can induce changes in their genetic sequence. We then speak of 'variants' or 'variant strains' to designate viral strains on which several mutations have been fixed. 

While these mutations are not affected most of the time, some can make it easier for viruses to enter cells, multiply faster and become more contagious. Still poorly known by the scientific community, these variant strains of the coronavirus could undermine the immunity developed by patients who have already been contaminated by Covid-19 and impact the effectiveness of vaccines placed on the market.

VOC, VOI, VUM: how are variants classified?

Variants of the coronavirus are classified into three categories, according to the consequences they can cause: 

Variants of Concern (VOCs). These are variants for which it has been demonstrated by comparing with one or more reference viruses:

- an increase in transmissibility or an adverse impact on the epidemiology of Covid-19;

- an increase in severity or a change in clinical presentation;

- a decrease in the effectiveness of the control measures put in place (preventive measures, diagnostic tests, vaccines, therapeutic molecules) OR

Variants to follow, or VOI ('variant under investigation' or 'variant of interest' in English). These are variants characterized by genetic modifications, which are known to affect (or are expected to affect) the characteristics of the virus such as transmissibility, disease severity, immune escape, ability to evade diagnosis or treatment. To be classified as ANI, a variant must also be responsible for significant community transmission in several countries, leading to increasing relative prevalence as well as an increase in the number of cases over time, or other observable epidemiological consequences that raise concerns about an emerging risk to global public health. 

Variants under monitoring (VUM). These are variants for which researchers do not yet have virological, epidemiological, or clinical evidence in favor of an impact in public health, despite the presence of mutations found in one or more VOCs or VOIs.

Other variants of Covid-19, where do we stand?

All about the Alpha variant (20I/501Y. V1)

Reported on December 14, 2020, to the World Health Organization (WHO), the variant 20I/501Y. V1 (Variant Alpha), appeared in England in September 2020. To date in metropolitan France, its prevalence is almost zero. It was replaced by the Delta variant.  

The Alpha variant is more contagious and deadly. "This variant is associated with increased transmissibility (from 43 to 90%) and possibly a more severe form of the disease, a higher risk of hospitalization (40-64%) and higher mortality (30-70%)," said Public Health France in its weekly report of April 29. In addition, this variant can contaminate dogs and cats. The British variant of Sars-CoV-2, called B.1.1.7 was first detected in February 2021 in a dog and a cat from the same household, in Brazos County, Texas (USA). In contrast, the risk of coronavirus transmission from pets to humans is considered low.

All about the Beta variant (20H/501Y. V2)

The beta variant, 20h/501y. V2 was detected in South Africa in December 2020. The results of genetic sequencing indicate its presence since November 2020. However, its presence has been a minority in France and is now almost nil.

Public Health France considered that the Beta variant was of concern because of its high contagion. "Preliminary studies suggest that this variant is associated with a 50% higher transmissibility and a higher risk of immune escape and reinfection. Some research indicates a 20% increased risk of death in hospitals. This variant would have the ability to evade the post-infection and post-vaccination immune response, and could therefore increase the risk of reinfection."

All about the Gamma variant (20J/501Y. V3)

Identified in early February 2021 in France, the Gamma variant, 20J/501Y. V3 would have emerged in December 2020 in Manaus (Brazil). Like the South African variant, it has the E484K mutation that could allow it to partially escape the body's immune response. This variant has remained a minority in France.

'Several studies show greater transmissibility compared to strains other than variants (from 40 to 120%). In addition, this variant would have the ability to escape the immune response induced by the first contact with strains of origin, and could therefore increase the risk of reinfection, "says Public Health France.

The impact of vaccination on this variant is still being studied. According to initial data, this Brazilian variant has two mutations E484K and N501Y on the Spike protein. The first would allow viruses to escape antibodies during reinfection or after vaccination.

Screening tests: how do you know if you are contaminated by a variant?

To combat the spread of variants, any test (antigenic or PCR) giving rise to a positive result must be subject to a second-line screening RT-PCR. "This second test makes it possible to determine if it is a variant," notes the DGS (Directorate General of Health). 

The laboratories use a specific RT-PCR kit, capable of distinguishing mutations from the classic strain and variants of the coronavirus. They must transmit the results within less than 36 hours to the laboratories that carried out the first PCR test.

Note: if you have performed an antigen test and it turns out to be positive, you will need to perform a second PCR test so that it can be screened.