A guide to help you keep up with the omicron sub-options
Two years into the coronavirus pandemic, Americans can be forgiven for losing sight of the latest options circulating at home and around the world. We’ve heard about alpha, beta, gamma, delta, and omicron variants, but the new Greek letter version hasn’t hit the scene in almost half a year.
Instead, over the past few months, there has been a seemingly endless stream of “sub-variants” of omicrons, the most recent Greek-letter variant.
How different are these sub-options from each other? Can infection with one subvariant protect someone from infection with another subvariant? And how well do existing coronavirus vaccines that were developed before omicrons deal with the sub-options?
We asked these and other questions to medical and epidemiological experts. Here is a summary.
Q: What are sub-options? How different are they from each other?
The omicron subvariants seem like an alphabetic soup of letters and numbers. The original version of the omicron was called B.1.1.529. The original omicron variant spawned sub-variants such as BA.1; BA.1.1; BA.2; BA.2.12.1; BA.3; and the most recent, BA.4 and BA.5.
“They all differ from each other by having different mutations in the spike protein,” which is the part of the virus that enters host cells and causes infection, said Dr. Monica Gandy, professor of medicine at the University of California, San Francisco. .
Smaller or moderate mutations in these subvariants may make them marginally more transmissible from person to person. As a general rule, the higher the number after “BA” in the name of a sub-variant, the more transmissible that sub-variant is. For example, BA.2 is thought to be 30-60% more contagious than the previous sub-variants.
These mutations allowed the subvariants to spread widely, but within a few weeks they were overtaken by a slightly more transmissible subvariant. Then the process is repeated.
In the United States, for example, BA.1.1 dominated late January, overtaking the original B.1.1.529. But by mid-March, BA.1.1 began to give way to BA.2, which became dominant by early April. By the end of April, another sub-option, BA.2.12.1, was gaining momentum, accounting for almost 29% of infections, according to the Centers for Disease Control and Prevention. (The late 2021 delta wave did not matter in this time frame.)
Q: What about the severity of the disease?
Fortunately, diseases caused by the omicron were generally less severe than those caused by the previous variants, a pattern that seems to hold true for all sub-variants studied so far. One analysis from Denmark found that BA.2 did not cause more hospitalizations than sub-variant BA.1, Gandhi said.
Even the most recently discovered sub-variants, BA.4 and BA.5, show “no evidence that it is more of a concern than the parent omicron, other than a potentially small increase in transmissibility,” said Brooke Nichols, an infectious disease specialist. is a specialist in mathematical modeling of diseases at Boston University.
Dennis Cunningham, systemic medical director for infection control and prevention at Henry Ford Health in Detroit, told NBC News that the symptoms of omicron subvariants “were fairly constant. There are fewer cases where people lose their sense of taste and smell. In many ways, it’s a bad cold, a lot of respiratory symptoms, nasal congestion, coughing, body aches and fatigue.”
Q: If you get infected with one subvariant, will you be protected from the others?
So far, in all variants to date, the ability of the virus to evade existing immune defenses is “only partial, as is the case with seasonal influenza,” said Colin Russell, professor of applied evolutionary biology at the Medical University of Amsterdam. Centre.
While some people who had BA.1 also got BA.2, initial research suggests that BA. 1 “provides strong protection against reinfection with BA.2,” said the World Health Organization.
“This may explain why our BA.2 spike in the US was not as big as the very big BA.1 spike in the winter,” Gandhi said.
The level of protection can vary depending on how sick you were: in mild cases, immunity increases for a month or two, and for recovery from a serious illness, up to a year.
Q: How do current COVID-19 vaccines counter these sub-options?
While current vaccines and boosters are not as successful at protecting against omicrons as they were against earlier variants, they tend to protect people from severe disease if they are infected with one of the newer sub-variants.
“We are stable when she works with the vaccines we use,” said Dr. William Schaffner, professor of preventive medicine and health policy at Vanderbilt University. “I have not seen a single field study that shows a significant difference between vaccine responses to the omicron sub-variants.”
Vaccines generate cells known as “memory B cells” and have been shown to recognize different variants as they appear, Gandhi said. Vaccines also trigger the production of T cells, which protect against serious diseases, she said.
“While B cells serve as memory banks to produce antibodies when needed, T cells enhance the body’s response to a virus and help recruit cells to directly attack a pathogen,” Gandhi said.
The end result is that a breakthrough infection for a vaccinated person “should remain mild with sub-options,” she said.
The widespread spread in the US of a relatively mild strain of the virus has likely paid off, providing many Americans with some immunity, whether or not they have been vaccinated. Studies show that people who were vaccinated and then became infected had even greater protection than people who were vaccinated and did not contract COVID.
“This family of omicrons can really offer a positive side in the course of the pandemic,” Schaffner said.
Looking ahead, vaccine manufacturers are starting to develop vaccines specifically targeting omicron, and some of them will combine the coronavirus vaccine with the seasonal flu vaccine in one shot. But those vaccines are in the early stages, and Schaffner said he suspects they won’t be ready and approved for flu season this fall.
Whether such new vaccines represent the next step in the fight against COVID depends on the FDA and CDC.
Q: Are there any brand new options on the horizon?
Experts agreed that the only newcomers to come out in recent weeks were incremental sub-variants — certainly nothing as game-changing as the delta or omicron when they first came out.
“We don’t yet know anything about what is hiding, and the surveillance is pretty damn aggressive,” Schaffner said.
Gandhi estimates that more than 60% of the world’s population has been exposed to omicrons and more than 65% of the world’s population has received at least one dose of the vaccine, “so I keep my fingers crossed that the development of new options will slow down with this degree of herd immunity.”
Gandhi admitted some surprise at how calm the horizon is now, but she sees that as a positive.
“It’s been five months since we heard about the new option, which I hope reflects the rise in immunity among the world’s population,” she said.
KN (Kaiser Health News) is a nationwide newsroom dedicated to in-depth health journalism. Together with Policy Analysis and Polling, KHN is one of the three major operational programs in KFF (Kaiser Family Foundation). KFF is a charitable non-profit organization providing health information to the nation.