Two years after the coronavirus pandemic, Americans could be forgiven for forgetting about the latest variant circulating across the country and around the world. We’ve heard of alpha, beta, gamma, delta, and omicron variants, but no new Greek variants have appeared in nearly half a year.
Instead, over the past few months, a seemingly endless stream of “sub-variants” of omicron, the latest variant of the Greek alphabet, has emerged.
How do these sub-variants differ from each other? Can infection with one subvariant protect someone from infection with another subvariant? How well do existing coronavirus vaccines (developed before omicron) work against subvariants?
We asked medical and epidemiological experts these and other questions. Here is an outline.
Q: What are subvariables? How different are they from each other?
The omicron subvariant looks like an alphabet soup of letters and numbers.The original omicron variant was called B.1.1.529. The original omicron variant gave rise to sub-variants such as BA.1; BA.1.1; BA.2; BA.2.12.1; BA.3; and more recently, BA.4 and BA.5.
“The difference between them is that spike protein,” which is the part of the virus that penetrates the host cell and causes an infection, said Dr. Monica Gandhi, a professor of medicine at UCSF.
Slight to moderate mutations in these subvariants can make them slightly more likely to spread from person to person. In general, the higher the number after “BA” in the subvariant name, the more transmissible the subvariant is.For example, BA.2 is think it is Transmissibility is improved by approximately 30% to 60% compared to previous sub-variants.
These mutations allow subvariants to spread widely, only taken over Via a slightly more transmissible subvariant within a few weeks. Then the process repeats.
For example, in the US, BA.1.1 dominated in late January, surpassing the original variant B.1.1.529.But by mid-March, BA.1.1 started to lose BA.2, became dominant by early April. By late April, another sub-variant, BA.2.12.1, began to circulate, accounting for nearly 29% of infections, According to data From the Centers for Disease Control and Prevention. (The triangle wave in late 2021 has been a non-factor in this time frame.)
Q: What is the severity of the disease?
Fortunately, diseases caused by omicron are often less severe than those caused by previous variants—a pattern that appears to hold for all subvariants studied so far. A Danish analysis showed that BA.2 Does not lead to more hospitalizations Gandhi said, than the BA.1 sub-variant.
Even the recently discovered sub-variants, BA.4 and BA.5said Brook Nichols, a mathematical modeler of infectious diseases at Boston University, “there is no evidence that it is more worrisome than the original omicron, other than a possible slight increase in transmission rates.”
Dennis Cunningham, Medical Director, Infection Control and Prevention System, Henry Ford Health Center in Detroit, tell NBC News Symptoms from the omicron sub-variants “are very consistent. People have a lower incidence of loss of taste and smell. In many ways, it’s a bad cold, a lot of respiratory symptoms, stuffy nose, cough, body aches and fatigue.”
Q: If you are infected with a submutant, will you be protected by others?
In all variants to date, the ability of the virus to evade existing immune protection”only partiallylike seasonal flu,” said Colin Russell, professor of applied evolutionary biology at the University Medical Center Amsterdam.
While some people with BA.1 are also infected with BA.2, preliminary studies suggest infection with BA. 1 “Robust protection against reinfection through BA.2”, World Health Organization Say.
“This may explain why our BA.2 surge in the US was not as large as the winter BA.1 surge,” Gandhi said.
The level of protection may vary depending on your condition, with mild cases likely to build up immunity for a month or two, and recovery from severe illness up to a year.
Q: How do existing covid-19 vaccines work against these sub-variants?
Although current vaccines and boosters are not as successful at preventing omicron as targeting earlier variants, they often protect people from severe disease if they become infected with a new subvariant.
“We’re pretty stable when she’s using the vaccine we’re using,” said Dr. William Schaffner, a professor of preventive medicine and health policy at Vanderbilt University. “I haven’t seen a single study in this area that shows that vaccines are effective in There were significant differences between the responses of the omicron sub-variants.”
vaccine generative cells known as “memory B cells” and has been shown to identify different variants When they appear, Gandhi said. The vaccine also triggers the production of T cells, prevent serious illnessshe says.
“While B cells act as a memory bank to produce antibodies when needed, T cells amplify the body’s response to viruses and help recruit cells to attack pathogens directly,” Gandhi said.
The end result, she said, is that breakthrough infections in vaccinated individuals “should remain mild in subvariants.”
The widespread spread of a relatively mild strain of the virus in the United States may have provided some immunity to many Americans, whether they had been vaccinated or not, which may have provided benefits. Studies have shown that people who have been vaccinated and then become infected have greater protection than people who have been vaccinated but not infected with the new coronavirus.
During the pandemic, “this omicron line can really offer a bright side,” Schaffner said.
Going forward, vaccine makers are starting to design vaccines specifically for omicron, and some will combine the coronavirus vaccine with the seasonal flu vaccine all at once. But it’s early days for those vaccines, and Schaffner said he suspects they won’t be ready and approved by this fall’s flu vaccination season.
Whether this new vaccine represents the next step in the fight against the new coronavirus will depend on the FDA and the CDC.
Q: Are there any brand new variants coming soon?
Experts agree that the only newcomers in recent weeks have been delta sub-variants—certainly nothing like delta or omicron when they first appeared.
“We didn’t know anything about what was lurking, and the surveillance was very aggressive,” Schaffner said.
It is estimated that More than 60% of the world’s population Exposure to omicron and above 65% of the world’s population Gandhi said he has received at least one dose of the vaccine, “so I’ve been praying that the development of new variants will slow down with this level of population immunity.”
Gandhi admits it’s a little surprising how calm the horizon is now, but she sees it as a positive development.
“It’s been five months since we heard about a new variant, which I hope reflects the increased immunity of the world’s population,” she said.
KHN (Kaiser Health News) is a national newsroom that provides in-depth news coverage on health issues.Along with policy analysis and polling, KHN is one of the top three operating programs in the U.S. KFC (Kaiser Family Foundation). KFF is a donating non-profit organization that provides information on health issues to the state.