Many people haven't had a vaccine dose in months, which means their immune protection against the virus is waning off with some studies showing three shots of the original vaccines were just 19% effective at preventing Covid infection after five months. At the same time, more transmissible omicron subvariants are spreading. It's creating a perfect storm ahead of the cold weather months and holidays that force people indoors in close proximity to each other and a highly contagious airborne pathogen. Even with all the tools the U.S. has available, Covid infections, hospitalizations and deaths have plateaued at stubbornly high levels over the summer.
The U.S. is gearing up for a booster campaign after Labor Day with reformulated vaccines that target both the original strain of the virus that emerged in Wuhan, China, in 2019 and omicron BA.5, the dominant variant in circulation. Public health officials believe the reformulated boosters will provide more durable protection against infection and help avert a major surge that taxes hospitals. "It's going to be really, really important for people to get this updated, new, very specific Covid vaccine because I think it's going to help a lot in preventing infections, and I think it is going to help a lot in keeping people out of the hospital," Jha said. The U.S. has so far secured 171 million doses of Pfizer's and Moderna's new boosters shots that target omicron.
New boosters
The reformulated boosters could reduce infections by 2.4 million, hospitalizations by 137,000 and deaths by 9,700 from August through May of 2023 if a new variant doesn't emerge, according to a projection by a team of scientists who forecast the trajectory of the pandemic, called the Covid-19 Scenario Modeling Hub. But the projection is based on optimistic assumptions about booster coverage and efficacy, according to the scientists. The model assumes that the shots will prove 80% effective at preventing illness, the vaccination campaign will ramp up quickly and the public will broadly embrace the new boosters. But many people in the U.S. still haven't gotten their first booster with the old vaccine yet, and it's not clear that these individuals will be more willing to take the new shots. About 76% of people ages 12 and older have received their first two vaccine doses, according to CDC data. Out of those people, about half have gotten their third shot. It's also not clear how effective the new omicron boosters will be in the real world yet. The Food and Drug Administration authorized the shots on Wednesday without results from human trials on the BA.5 shots. But Dr. Peter Marks, head of the FDA office responsible for reviewing vaccines, said the available data suggests the shots will provide substantially better protection. Public health officials are working under the assumption that the U.S. will face some version of omicron in the fall, which is why the new vaccines target BA.5. But there is always the risk that a new variant outside the omicron lineage will emerge that can evade the new shots. If Covid mutates in a way that gives life to a new, dominant variant and boosters are slow to get out to the public, the U.S. could suffer 1.3 million hospitalizations and 181,000 deaths over the next nine months, according to the scientists' most pessimistic scenario. But Michael Osterholm, director of Center for Infectious Disease Research and Policy at the University of Minnesota, said the reality is that nobody really knows what will happen in the fall. "We don't know," he said.
Most Americans have antibodies
Ali Mokdad, an epidemiologist at the Institute for Health Metrics and Evaluation at the University of Washington, said his group is predicting a rise in Covid cases, deaths and hospitalizations this fall. "But the rise in mortality and hospitalization will not be similar to what we have seen before, simply because most people have some kind of immunity against illness," Mokdad said. About 95% of people ages 16 and older in the U.S., in fact, have Covid antibodies of some sort — either from vaccination or prior infection, according to a CDC survey of blood donor data. This means more people in the U.S. have at least some protection against severe disease and death from Covid than at any other point in the pandemic. Previous infection, vaccination alone and vaccination plus infection didn't necessarily keep people from getting sick, but they all showed more than 70% effectiveness against developing a really severe case or dying from omicron BA.2 , according to a study published in the New England Journal of Medicine by Weill Cornell Medicine in Qatar. The study examined the medical records of 100,000 individuals in Qatar from December 2021 through February 2022.
But the Qatar study may not translate well to the U.S. population, which has a large elderly population and many people with preexisting medical conditions, like obesity or diabetes. Qatar on the other hand has a very young population — only 9% of its residents are age 50 or older compared with more than a third of all Americans. Omicron has also continued to evolve into more transmissible and immune-evasive subvariants. The BA.5 subvariant became dominant this summer, pushing out BA.2. Though BA.5 has not been associated with more severe disease, it is more effective at evading immunity and infecting people who are vaccinated or who have recovered from Covid. "BA.5 is the most contagious, certainly the most immune evasive variant we've seen," Jha told NBC News in July. "That means if you were infected earlier this you're still at very high risk of reinfection. It means if you've not been vaccinated recently you have a very high risk of having a breakthrough."
Waning immunity
While the CDC previously thought that infection provided about 90 days of protection, Jha told reporters in July that breakthrough infections have become more common and are happening earlier with BA.5. He said it's unclear how long immunity lasts after recovering from a BA.5 infection. Osterholm said the pandemic has entered another unprecedented period. Previously, infections have surged to high peaks and then steeply declined before the next wave. But for the past three months, infections, hospitalizations and deaths have plateaued at a high level with no sign of another variant displacing BA.5, he said. "We're seeing now more and more people are on their second and third episodes of this," Osterholm said. "What is the interaction between increasing vaccination, natural infection and immunity related to infection? We just don't know," he said. It's unclear whether the current pattern of transmission will continue or if the U.S. will face another wave, Osterholm said. Right now, the U.S. is averaging more than 88,000 new infections daily, which is likely a vast undercount because people testing positive at home isn't picked up by the official data. More than 32,000 people total are hospitalized across the U.S. with Covid right now, and an average of nearly 400 people are still dying every day from the virus, according to data from the CDC and the Health and Human Services Department. That's a significant improvement from the peak of the outbreak in the winter of 2021 when more than 3,000 people died a day on average. Though milder today than those early days of the pandemic, Covid is still killing at four or five times the fatality rate of the flu, Jha told the Chamber. "If everybody was up to date on their vaccines and people got treated with Paxlovid as they're supposed to deaths would go to close to zero across America," Jha said. Hospitalizations are down 75% and deaths are down 85% from the peak of last winter's omicron surge. But if deaths remain at their current level through next year, more than 140,000 people would succumb to the virus, which would still make Covid one of the 10 leading causes of death in the U.S. "Will we continue to see this kind of activity maintained for some time? People will say it can't go on endlessly because people will be infected and develop immunity. But what happens with waning immunity?" Osterholm said.
Focus on the vulnerable
Many elderly people and individuals with weak immune systems remain vulnerable to the virus. The rate of hospitalization and death from Covid has increased among those ages 65 and older since April despite high levels of vaccination in this age group, according to CDC data. Jennifer Nuzzo, an epidemiologist at the Brown University School of Public Health, said she is worried about the elderly and those with weak immune systems who are not up to date on their vaccines heading into the fall. Nuzzo said the public health response this fall should be laser focused on making sure these people are protected. "I have some worry that unless we put that at the top of our list, our efforts are just going to be diluted, spread out over a number of different areas," Nuzzo said. "If we fail to make sure the highest risk people are fully protected, that's when we're going to see the deaths and that's the most important thing we could try to prevent." Although 92% of those ages 65 and older received the first two doses of the vaccine, many of them have not stayed up to date with their boosters. About 70% received their third dose and only 40% have gotten their fourth shot since the FDA authorized it in February. People ages 50 and older who received a second booster dose were 14 times less likely to die from Covid than the unvaccinated, and three times less likely to die than people who had one booster dose, according to CDC data. Dr. Paul Offit, an infectious disease expert at Children's Hospital Philadelphia, said people ages 75 and older, people with serious medical conditions and those with compromised immune systems would benefit the most from getting a booster right now. Deaths from Covid have risen in particular among people ages 75 and older, according to CDC. The CDC has also emphasized the importance of using therapeutics to protect people who simply cannot mount a strong immune response to the virus even with vaccination. Nearly 3% of U.S. adults have compromised immune systems, or about 7 million people ages 18 or older, according a survey published in 2016 in the Journal of the American Medical Association. The CDC has emphasized the importance of administering an investigational antibody therapy called Evusheld for people ages 12 and older with moderate and severely compromised immune systems. Evusheld is administered as two injections, before Covid infection, every six months to prevent severe illness, according to the FDA. But only 450,000 courses of the medicine have been administered so far, according to the health and Human Services Department.
"The goal moving forward here for this year, next year, five years and 10 years down the road is protecting the vulnerable," Offit said.
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