(CNN) – With a new version of the Omicron coronavirus variant emerging in the United States, up to 28 million elderly people are still at risk of severe illness from Covid-19, because they have not been vaccinated or have been partially immunized, or because it’s been more than five months since they got their second or third dose of the vaccine, according to CNN’s analysis of federal data.
As the United States focuses on the increased cases caused by the subvariable BA.2 in Europe, the immune status of adults over 65 years of age will be a key indicator of how future variants will affect to the United States because the risk of serious outcomes is significantly increased. with age.
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“Really looking at that older age group and their previous level of immunity, from previous infections or vaccinations, which I think is the best indicator by far of the severity of some cases. the merger will end. Stephen Kissler, who specializes in infectious disease modeling at Harvard’s TH Chan School of Public Health, said.
An analysis The British Health Security Agency found that Omicron’s sub-microbe BA.2 is growing about 80 percent faster than BA.1, the virus that caused the last wave of infections in the US during the winter. Cases and hospitalizations are on the rise in the UK and several other European countries, where BA.2 has become the dominant strain.
Although a direct comparison with BA.1 indicates that BA.2 is not more likely to lead to hospitalization, this variant is likely to overwhelm US healthcare resources again if it were to find enough susceptible people.
The most susceptible group is adults over the age of 65, especially those with low immunity against the virus. This is why Pfizer and BioNTech asked the US Food and Drug Administration this week to give the green light for a fourth dose of the vaccine for older adults.
“It is the group that has the most problems when it comes to critical illness and death. That’s not to say young people don’t go to the hospital sometimes; Jeffrey Shaman, who specializes in modeling the spread of infectious diseases at Columbia University’s Mailman School of Public Health, said.
Shaman only come Hong Kong, is being affected by a severe wave caused by BA.2. It has the highest Covid-19 death rate in the world.
“And they haven’t seen the full impact of that yet because it’s a little late, but that’s because they have an under-vaccinated elderly population,” he said.
US officials do not expect BA.2 to have as much of an impact here as in Hong Kong. That’s because the city has pursued a zero-tolerance Covid strategy. That policy has kept cases and deaths low so far, making it a model for Covid control.
But Omicron and BA.2 overwhelmed those defenses and began infecting a population with little previous exposure to the virus.
Hong Kong also relies on a slightly different mix of vaccines than the US and Europe, including the Chinese-made Sinovac and Pfizer Comirnaty vaccines.
Health officials are looking to the UK for clues about how BA.2 might work in the US. But they are not the same in every way; Most notably, the UK is more vaccinated.
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In general, in the UK, 82% of adults injected a third dose of the Covid-19 vaccine, which is crucial to preventing infection and hospitalizations from Omicron because of how likely these variants are to be “highly immunogenic,” Shaman said. In America, that the number is only 36%.
Among Americans over 65 years of age eligible for booster shots, CDC data found that 1 in 3 people didn’t choose to get a third dose — leaving about 15 million older Americans without that important extra protection.
Protection fades over time
Recent studies show that vaccination timing is also important. Data collected by the UK’s Health Security Authority shows that the vaccine’s effectiveness against Omicron drops to 10% for infections, 35% for hospital admissions and 70% for deaths six months or more after the second dose.
Boosters have restored much of that protection, but their benefits have also waned. Four to six months after the third dose, the booster is about 40% to 50% effective in preventing Omicron infections and 75% to 85% in preventing hospitalization, for all adults.
In the UK, around two-thirds of seniors have received a second, third or fourth dose of the Covid-19 vaccine within the past five months, but only about half of seniors in the US have received a dose of the vaccine. – Apply for a second or third within five months.
Comparing the ability of antibodies to protect against Covid-19 infections or vaccinations in the past, the UK is ahead again. At the end of February, 98% of adults in the UK had tested positive for antibodies to Covid-19, according to National Statistics Office. In U.S.A, CDC estimates that 43% of Americans have antibodies from a past infection to fight Covid-19. However, the elderly are the least likely to receive this protection, with only 23% of adults over the age of 65 testing positive for antibodies from a previous infection.
Kissler told CNN: “I still think it’s a potential cause for concern that we could still see a higher case fatality rate and a higher number of Covid hospital admissions in the US than in the UK because of the increased morbidity and mortality associated with the virus. differences in baseline immunity”.
So while the wave of BA.2 in the US may not be as severe as in Hong Kong, it may not be as severe as it is in the UK.
“What we see happening in the UK is probably going to be a better story than what we should expect here,” said Keri Althoff, an epidemiologist at the Johns Hopkins Bloomberg School of Public Health.
With perhaps an important few weeks to prepare, Kissler and Shaman say immunizations and boosters for seniors is an important place to start.
“Every extra layer of protection we get will help, and so I strongly recommend doing so, especially unvaccinated older people because it can really help you get the most out of your life. immunity is as durable and strong as you want it to be. ,” Kissler said. “This is definitely the moment.”
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https://baltimore.cbslocal.com/2022/03/17/this-key-indicator-may-determine-how-bad-a-ba-2-wave-could-be-in-the-us/ This key indicator could determine how bad the US BA.2 wave is – CBS Baltimore