2021-02-11 08:59:53
The Covid-19 virus is constantly mutating and many variants of SARS-CoV-2 are circulating around the world. Some are qualified as “variants of concern” (VOC) or “variants to monitor” (VOI) because their impact (transmissibility, contagiousness, potential immune escape) justifies the implementation of specific surveillance and specific management measures. The Omicron variant, and in particular its EG5.1 sublineage (Eris), currently holds the majority in France.
Variant Omicron (B.1.1.529): characteristics, seriousness, vaccine…
The Omicron variant represents today 100% of Covid-19 footage analyzed in France. This variant of the coronavirus has been detected on November 25, 2021 in South Africa. Baptized “Omicron” by the WHO (B.1.1.529), it has an “extremely high” number of mutations. “The three major characteristics of Omicron are its high transmissibilityits immune escape and its lesser severity “according to Public Health France.
A lower hospitalization rate with the Omicron variant than with Delta
The number of intensive care hospitalizations linked to the Omicron variant would be lower than with the Delta variant which circulated last fall and winter. According to a study published on January 10, 2022 by the Assistance Publique-Hôpitaux de Paris (AP-HP), the probability of having recourse to critical care was thus “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 in conventional hospitalization.
A vaccine specific to Omicron
In September 2022, several new vaccines (developed by Pfizer and Moderna) were accepted in Europe and France to fight more specifically against the Omicron variant. These so-called vaccines bivalents target Omicron BA.1 subvariants, as well as BA.4 and BA.5 along with the original strain of Covid-19. In an opinion published on September 20, 2022, the HAS (Haute Autorité de Santé) “recommends using one of the three bivalent vaccines adapted to the Omicron variants recently validated by the European Medicines Agency” as a booster dose. for people at risk and their families (source 1). According to WHO (World Health Organization) Director General Tedros Adhanom Ghebreyesus, the reinfection rate of the Omicron variant is much higher than with other variants of Covid-19.
BA.4, BA.5, Eris… which Omicron sub-variants are circulating? what symptoms?
What are the different Omicron sub-variants? What do we know about their circulation and their symptoms?
Circulation in France, symptoms… what do we know about the Eris variant (EG5.1)?
The sous-variant Omicron Eris (EG5.1), originally spotted in India, would be in the majority today in France, but also in the United States and the United Kingdom in particular. It has been classified as “variant to be followed by the WHO” and would be the cause of an increase in the Covid-19 epidemic this summer 2023. It would therefore be potentially more contagious than the variants that have been circulating so far. It is associated with the symptoms usually encountered with Covid-19: cough, sore throat, fatigue, fever, headache…
BA.4 and BA.5: what is their circulation? what are their symptoms?
In France, the sub-variants of Omicron BA.4 and BA.5 continue to circulate. Faced with the contagiousness of these variants, they are classified as “ variants of concern under WHO supervision.
According to a risk analysis of Covid-19 variants from Santé Publique France published on June 15, the most frequent symptoms in the event of infection with variants BA.4 and BA.5 are:
- the fatigue ;
- cough ;
- fever ;
- headaches ;
- stuffy or runny nose.
Other symptoms not previously reported appear, such as digestive disorders. “The probability of have anosmia (loss of smell) and ageusia (loss of taste), but also nausea, vomiting and diarrhea is higher for cases of BA.4 / BA.5 ”details the health agency. There duration of clinical signs is on average 7 days for the cases of BA.4 and BA.5. After infection with other Omicron subvariants, symptoms lasted an average of 4 days.
© Age and symptoms of BA.4 and BA.5 cases compared to BA.1 cases. French Public Health.
Less or more circulating variants of Covid-19
All about the Alpha variant (20I/501Y.V1)
Reported on December 14, 2020 to the World Health Organization (WHO), le variant 20I/501Y.V1 (Alpha variant), appeared in England in September 2020 and was the majority in France in 2021. To date in metropolitan France, it no longer circulates.
This variant is associated with a increased transmissibility (from 43 to 90%) and possibly a more severe form of the disease, a higher risk of hospitalization (40-64%) and a higher mortality (30-70%)”, indicated Public Health France in its weekly report of April 29, 2021. In addition, this variant can contaminate dogs and cats. On the other hand, the risk of transmission of the coronavirus from pets to humans is considered low.
All about the Beta variant (20H/501Y.V2)
The Beta variant, 20H/501Y.V2was detected in South Africa in December 2020. However, its presence was minor in France in 2021 and is currently nil.
Public Health France considered the Beta variant to be of concern due to its high contagion. “Preliminary studies suggest that this variant is associated with a 50% higher transmissibility and one higher risk of immune escape and reinfection. Some research indicates an increased risk of in-hospital death of as much as 20%. 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 which could allow it to partially escape the body’s immune response. This variant remained a minority in France and is no longer localized.
Delta variant: contagion, diffusion, dangerousness
The Delta variant was first identified in the fall of 2020, in the region of Nagpur, India. To date, this variant is not almost no longer detected.
It is classified as a variant of former concern by the WHO. The highly contagious Delta variant has reduced the effectiveness of vaccines by 40% against the transmission of Covid-19, announced the boss of the World Health Organization (WHO), Wednesday, November 24.
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. Each of the Indian variants involves a different risk, according to the Scientific Council (opinion of May 24, 2021):
- The B.1.617.2 sublineage (Delta variant) was the most frequently detected lineage in France and Europe. Note that it also contains additional specific mutations that can give it a greater transmissibility advantage than the other two lines.
- The B.1.617.1 sublineage, (Kappa variant) which also presents the combination of the two mutations, was detected in Europe and in France, but at a low frequency compared to the B.1.617.2 lineage. Of the three viruses, it is the one with the greatest antigenic difference compared to the historic “Wuhan” strain and therefore a risk of immune escape. It is VOI rated.
- The sublineage B.1.617.3which has the combination of L452R mutations (which may be associated with increased virus transmissibility) and E484Q (responsible for post-infectious and post-vaccination partial immune escape) has spread very little in India and outside India. India.
Variant XD or “Deltacron”: what is it?
You can be infected by two variants of Covid at the same time. This phenomenon is the peculiarity of variant XD. This variant is a recombinant from Delta and Omicron (ex- “Deltacron”). Detected for the first time in January 2022, this variant has almost disappeared in France, it has been detected at low levels since early January 2022 and accounted for less than 0.1% of infections in the country according to Public Health France. His symptoms were the same as with the Omicron variant, with a higher rate loss of taste and loss of smell.
How to explain this phenomenon ? “When two variants are circulating at the same time, some people can be infected with two variants simultaneously. These co-infections can lead to recombination phenomenathat is to say exchanges of genetic material between the two variants » explain French Public Health. The recombinant therefore has a genome corresponding in part to that of the first variant and in part to that of the second variant and this is the case of the XD variant.
What protective measures against variants of Covid-19?
In order to protect against variants of the coronavirus, it is important to maintain barrier gestures. On the other hand, there is no longer any insulation obligation since February 2023.
What to do when you are a contact or positive case for Covid-19?
It is recommended for people with contact and positive cases certain sanitary rules to break the chains of transmission of Covid-19:
- realize immediately a screening test (RT-PCR or antigenic test);
- in the event of a positive test, inform the people you have met within 48 hours after meeting the sick person and recommending that they limit their contact;
- respect barrier gestures ;
- limit social interactions and avoid contact with people at risk severe even if they are vaccinated;
- wear a mask in the presence of other people;
- perform self-monitoring of temperature and possible onset of symptomswith an immediate screening test in case of symptoms, regardless of age.
Reminder: what is a variant?
By definition, viruses constantly mutate to adapt to the hosts they infect. The more viruses spread, the more they must mutate in order to remain “efficient” “. But when viruses multiply in cells, their “recopying” 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.
Although these mutations have no impact most of the time, some may allow viruses to penetrate more easily into cells, to multiply there more quickly and to become more contagious. They can also undermine immunity developed by patients who have already been infected with Covid-19 and impact the effectiveness of vaccines put on the market.
VOC, VOI, VUM: how are the variants classified?
Variants of the coronavirus are classified into three categories by the World Health Organization (WHO), according to the consequences they can cause:
- The variants of concern, or VOC (“variant of concern” in English). 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 (prevention measures, diagnostic tests, vaccines, therapeutic molecules) OR - The variants to follow, or VOI (“variant under investigation” or “variant of interest”). These are variants characterized by genetic changes, which are known to affect (or are expected to affect) characteristics of the virus such as transmissibility, disease severity, immune escape, ability to escape diagnosis or treatment. To be classified as a VOI, a variant must also be responsible for significant community transmission in multiple countries, resulting in increasing relative prevalence as well as an increase in the number of cases over time, or other observable epidemiological consequences that raise concern an emerging global public health risk.
- The variants under evaluation, or VUM (“variant under monitoring”). These are variants for which researchers do not yet have conclusive virological, epidemiological or clinical evidence in favor of a public health impact, despite the presence of mutations found in one or more VOCs or VOIs.
Screening tests: how do you know if you are infected with a variant?
To combat the spread of variants, any test (antigen, self-test) giving rise to a positive result must be subject to Second-line screening RT-PCR. “This second test makes it possible to determine whether it is a variant”, notes the DGS (General Directorate of Health).
The laboratories use a specific RT-PCR kit, capable of distinguishing between mutations of the classic strain and variants of the coronavirus. They must send the results within less than 36 hours to the laboratories that carried out the first PCR test.
Please note: if you have performed an antigen test and it is positive, you will need to perform a second PCR test so that it can be screened.
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