Overview of the most important SARS-CoV-2 variants:
Overview of the most important SARS-CoV-2 variants:
How effective is the vaccine protection?
How infectious is the variant??
Risk for severe courses? How virus mutations occur. How can they make the virus more dangerous?Unlike bacteria, viruses cannot survive for long on their own. They need cells into which they can insert their genetic information and which they can use for reproduction. In the case of SARS-CoV-2, human somatic cells serve as hosts for the viruses. Here they multiply. The genetic material is also copied in the process -. Small errors keep happening during this copying process. The resulting changes in the genome are called mutations.
Many of these mutations are not noticeable at all, they have no significant effect. However, there are also mutations that have greater effects. Some take away the ability of the virus to survive. For example, by making it more susceptible to the body's defense mechanisms, the viruses lose their ability to invade other cells. These newly formed variants perish rapidly.
Other mutations, on the other hand, give the virus advantages in spreading: they may be better able to avoid the immune cells of the human body or penetrate host cells more quickly.
Explainer video: How mutations occur in viruses?
The law of evolution also applies to viruses
The variants that have such an advantageous mutation are more likely to spread. Darwin's law of evolution is at work here: survival of the fittest. A mutation is a random change, nothing more. But: the incessant wandering helps the virus, with its changes and their effects, to eventually adapt to environmental conditions that are also changing.
"It is quite natural that corona viruses, just like influenza viruses, mutate again and again", says Roman Wolfel, senior physician and head of the Institute for Microbiology of the German Armed Forces, Munich. "Corona viruses are even rather slow in terms of mutation, by the way, because they strive to incorporate comparatively few errors into their genome." Nevertheless, their rate of mutation has been sufficient to repeatedly produce new variants since the beginning of the pandemic, giving the viruses important advantages.
Which variants are considered "variants of concern"??
Among the variants currently circulating, the World Health Organization (WHO) has classified the delta variant and the omicron variant as "variants of concern". [1] In the case of the Omikron variant, subvariants are also explicitly classified as a concern, including BA.1, BA.2, BA.3, BA.4, BA.5 as well as the recombinant form XE.
Since the beginning of 2022, the Omikron variant has consistently dominated in Germany. In January, the omicron sub-variant BA released.1 replaced the delta variant as the dominant variant, then in February BA.2 the dominant variant in this country. Currently (as of 22.4.2022) is BA.2 still the predominant variant.
The alpha, beta and gamma variants of the coronavirus are also considered of concern by the WHO, but they have already been displaced by the delta variant in 2021 and have not been detected in recent weeks. [2]
What is known about the predominant omicron variant?
Since the beginning of the year, the focus has been on the Omikron variant, which was first discovered in South Africa. Omicron has been the predominant variant worldwide since January and has various subvariants such as BA.1 and BA.2. These subvariants in turn have combined with each other again. The variant Omikron XE, for example, discovered in the UK in January, is caused by a combination of BA.1 and BA.2 emerged. So far, however, Omikron XE has not spread.
The currently dominant omicron sub-variant BA.2 has two major differences from the Delta variant, which was displaced by Omikron at the turn of the year.
BA.2: Omicron variant predominant
BA.2 is a subtype of the Omikron variant, which now dominates the infection incidence in Germany. What does this mean for the further course of the pandemic??
First, a BA.2 infection more contagious than the Delta variant. Overall, Omikron is already spreading much faster than any of its predecessors – including Alpha, Beta and Delta. And the BA sub-variant.2 spreads probably once again faster than BA.1. Even vaccination offers only limited protection against infection: for triple-vaccinated persons, the risk of contracting the disease from a person infected with SARS-CoV-2 in the household is more than three times higher with omicron than with the delta variant. Compared to the risk of unvaccinated individuals, however, it is of course still quite substantially reduced.
This all suggests that Omikron's mutations appear to have enhanced its ability to bypass the human defense system to some extent. At the same time – since vaccination no longer protects against infection as efficiently – more people have again become susceptible to the virus.
Second, the courses of omicron infection are probably milder. So far it looks like it is also in BA.2 the case, taking into account that vaccination protection also influences the course of the disease. According to a study from the United Kingdom, the risk of death in people between the ages of 60 and 69 is about 86 percent lower with omicron infection than with the previously prevalent delta variant. [3]
How well do vaccinations protect against omicron and its subvariants? Current vaccinations provide only limited protection against infection with omicron -. The protective effect wears off again some time after vaccination. But vaccination provides good protection against a severe course even in the case of omicron infection -. This can be crucial for health. In the weeks after the last vaccine dose, protection against hospitalization for a severe course is 82 percent in boostered individuals. But even 15 weeks after the last vaccination dose, the protection is still 54 percent. However, these are figures from a pre-released. Thus, not yet second-assessed investigation in adults up to the age of 64 years. [5]
Now, given the decline in vaccine protection, one might get the idea of keeping one's immune system alert with regular booster shots. However, this approach may quickly reach its limits: According to a study from Israel, which has also only just been published, antibody levels probably rise as expected after the fourth vaccination, but this has resulted in only a small amount of additional protection against infection with the virus. [6] A second booster vaccination is therefore so far only recommended for certain groups of people with a particular risk of severe courses.
Omikron: questions and answers
How Omikron differs from other SARS-CoV-2 variants and what is known about subtypes such as BA.2 are known
Which important variants are still? Currently, the Omikron variant dominates. Its sub-variants the event. Earlier variants such as alpha, beta, gamma and increasingly also delta hardly occur anymore.
Researchers are therefore paying particular attention to possible new sub-variants of Omikron:
Omikron XE – a combination of the BA subvariants.1 and BA.2 is currently underway in the UK.
It apparently has another spreading advantage over BA.2, it is about 10 percent, estimates epidemiologist Maria Van Kerkhove of the World Health Organization. [7] However, whether this advantage is sufficient to make BA.2 to be suppressed in the coming weeks and months is questionable. For example, the first case of Omikron XE was reported as early as 19. January in the United Kingdom, but even in early April, Omikron XE was still less than one percent of new infections. [8]
What is the new variant Omikron XE all about??
More than 1000 cases of the new Corona subtype have been found in the UK. Will it prevail?
Omikron XD and XF – both are combinations of Delta and BA.1.
Therefore, they are sometimes laxly referred to as delta crones. Omikron XD is being monitored by the WHO; individual cases have been observed here, especially in France. For both variants, however, there is so far no definite evidence of a greater prevalence or differences in progression.
Increasing the risk of reinfection by the new variants?
In experiments with the blood of recovered Covid-19 patients, it was observed that the antibodies contained therein often did not prevent infection of cells with the newer variants very efficiently. Researchers therefore suspect that the new variants could result in a higher risk of a second infection after a person has already been through covid-19 disease.
Similar to vaccine efficacy, however: An infection that has already run its course is also likely to protect against a new infection to a certain extent – but by no means completely. "Even if mutations have changed the proteins of the virus to such an extent that the antibodies formed during a previous infection no longer recognize them, then the T cells are still there to recognize small sections of the virus and provide a cellular immune response," says Professor Christine Falk, president of the German Society for Immunology (DGfI).
Can I particularly protect myself against new variants?
It is still important to consistently adhere to the AHA+L recommendation: Keep your distance, observe hygiene, wear mouth-nose protection in everyday life, and ventilate regularly. And keep contacts to a minimum.
A complete vaccination series is also important in order to have the best possible protective effect, especially against severe courses of the disease. The Standing Commission on Vaccination (Stiko) recommends a third vaccination, the so-called booster vaccination, for all people over 18 years of age, as the vaccination protection against severe disease also decreases over time. People over 70 years of age are also recommended to receive a fourth vaccination. The same applies to certain other groups of people with an increased risk of a severe course of the disease.
Questions and answers about booster vaccination
The Standing Committee on Vaccination recommends booster vaccination against Covid-19 now for all adults. Who should be vaccinated and when, and what applies to certain groups of people
What is being done about the new variants?
Experts are trying to tackle the mutations on three levels.
First – Test: mutations in the viral genome must first be found. This requires more sophisticated testing of the virus than the normal PCR test for detection.
Second – understand: Researchers worldwide are currently working to better understand the mutations of the virus. That also includes finding any vulnerabilities. The vaccines then try to adapt them to new mutations as quickly as possible.
Third – protect: To prevent the emergence of new variations, scientists recommend something else that sounds as simple as it is difficult: the number of new infections worldwide should be kept as low as possible. Because the more viruses circulate, the more mutations occur. And every mutation is a chance for the virus to produce an optimal variant that can spread better.
According to experts, in order to reduce the number of new infections worldwide, it is important that the vaccines finally reach regions where they have been lacking up to now and where the vaccination rate is therefore still negligibly low. "It is now high time to distribute the vaccines worldwide now, and no longer to think only – this applies especially to the industrialized countries – of our own supply. Because we won't be safe until the world is vaccinated," says Professor Norbert Suttorp, Director of the Medical Clinic with a focus on infectious diseases and pneumology at Charite Universitatsmedizin.
How will it continue?
While it's impossible to say for sure, there is at least some hope that the virus will morph into a variant that may be more contagious, but more harmless. There are obvious reasons for this: An aggressive variant that quickly makes those it infects seriously ill is less likely to be passed on, precisely because those affected have symptoms and then hopefully isolate themselves or become less mobile.
The recent course of the pandemic confirms this principle: the delta variant was displaced by the omicron variant a few months ago – the latter spreads faster but probably has a milder course of disease.
When it comes to the further course of the pandemic, the so-called spike protein of the virus is also likely to play a supporting role. It sits on the surface of the viruses and fulfills an important function: With the spike protein, a virus can dock onto the cell surface of human cells, for example in the nasopharynx, and infect these cells.