If I have used Omicron before, is it safe from infection by new variants?

When it comes to Omicron, there is one thing that is certain for bioinformatics Shishi Luo. That is another surge.

This is due to the emergence of a new version of Omicron. Not just here in the United States, but in other parts of the world, such as South Africa.

These new variants have a series of important mutations that allow them to spread even faster than previous versions of Omicron.

So people are wondering: If I had Omicron once, can I get it again?

Two preliminary surveys published online this week are now beginning to answer that question. And the results show how quickly Omicron can mutate and overcome the defenses of the immune system.

Subspecies situation in the US and South Africa

Before we dive into the study, let’s take a look at what these variants are doing in the United States and South Africa.

In the United States, a new version of Omicron called BA.2.12.1 Appeared Incidents surged in central New York last month. BA.2.12.1 is now found nationwide and spreads about 50% faster each week than Omicron BA.2, which was the predominant US variant.

“How is this? [new] Variants are currently rising in the United States and will definitely dominate here, “says Luo. How big is the bump? I don’t know the answer. It really depends on what people do. ”

In South Africa, two of these new Omicron variants, known as BA.4 and BA.5, are causing the wave of the fifth case. In the last two weeks, the number of cases has almost quadrupled from about 1,200 per day to 4,600 per day. And the positive rate jumped from about 8% to 18%.

Omicron is a “master player”

These new variants show how smart Omicron is.

“Omicron is a master player in terms of its ability to evade antibody activity, which is much more efficient than all previous variants,” says virologists. Pay Young Sea At the University of Texas School of Medicine in Galveston, who was not involved in the newly published study. “As in this case, you need just a significant mutation that can completely turn things over.”

Two new studies are suddenly beginning to explain why these new variants have begun to spread rapidly. The answer is summarized in one key factor: those mutations allow them to reinfect people who already have Omicron infection. The risk of this reinfection may be higher in unvaccinated people.

In the study, researchers took blood from people infected with the original Omicron variant BA.1 and investigated whether antibodies in the blood could neutralize new versions of Omicron, including those that appeared in New York. (BA.2.12 .2) or two variants (BA.4 and BA.5) that are proliferating in South Africa.

Everyone infected with Omicron BA.1 had antibodies that could neutralize BA.1. However, its potency was dramatically reduced for the new variants (BA.2.12.2, BA.4, and BA.5). And how much it decreased depended heavily on whether people were vaccinated.

Both studies reported that for unvaccinated people, the ability of antibodies to neutralize BA.4 and BA.5 was reduced by almost 8-fold compared to their activity against BA.1. increase.

“Neutralization ability … very low after BA.4 / 5” Immunologist Alex SegalLed one of the studies, I have written On Twitter. Researchers at Peking University reported that the efficacy was about four-fold lower than BA.2.12.1.

“In summary, our results show that Omicron can evolve mutations and specifically avoid BA.1 -induced immunity. [omicron] Infectious diseases “, biophysicist Sunny Xie And his colleague at Peking University write In one of the studies.

What you can and cannot do with vaccines

“The situation was better for the groundbreaking vaccinated cases,” added Cigar of the African Institute of Health. For people immunized with either the Pfizer vaccine or the Johnson & Johnson vaccine, the neutralizing capacity was only 3-fold reduced against BA.4 and BA.5 compared to its efficacy against BA.1. These people also had more neutralizing capacity for BA.1 in the first place. Thus, in the end, it was on average about five times more effective in neutralizing new mutants than those who were not vaccinated prior to infection.

“The data have repeatedly shown that vaccines still offer tremendous benefits,” says Pei-Yong Shi, a virologist in Galveston, Texas.

Nonetheless, Sigal believes that this diminished antibody potency is sufficient to “cause problems and lead to a wave of infection,” as in South Africa, where only about one-third of the population is immunized. I am.

Bioinformatics engineer Tuliode Oliveria I accept. “The previous Omicron BA.1 infection is not enough to prevent a second infection of BA.4 and BA.5,” said de Oliveria at the Epidemic Response and Innovation Center in Durban. .. I have written On Twitter.

“Some scientists and science communicators are convinced that new varieties are needed to create a new wave,” added de Oliveira. “Delta caused long waves in multiple systems. Omicron caused waves in BA.1, BA.2, BA.2.12.1, BA.4, BA.5.”

Both BA.4 and BA.5 are very rare here in the United States. No one knows if it can compete with BA.2.12.2. account The US Centers for Disease Control and Prevention estimates about one-third of all cases in the United States. “The case of BA.2.12.2 is increasing exponentially,” he said. Helix’s Shishi Luo.. “Depending on the rate of its exponential growth, we can see a very rapid increase in cases nationwide next month or so.”

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