COVID-19 IN FLORIDA 2/9/22
Experts: Herd immunity unlikely
By Caroline Catherman Orlando Sentinel
Morgues overflowed, intensive care patients were treated in hallways and over 60,000 of Florida’s friends, family members, and community leaders died of COVID-19 as of Tuesday. As the pandemic progresses, it’s comforting to imagine there is a point where the virus won’t be a problem anymore.
Some people have touted “herd immunity” as that point. Herd immunity — also known as community immunity — is when a virus is unlikely to spread because a high percentage of the population is immune via infection or vaccination, according to the Association for
Professionals in Infection Control and Epidemiology. In this scenario, people without immunity are protected because they have such low odds of being exposed.
Dr. Anthony Fauci, White House chief medical advisor, initially predicted 60% to 70% vaccination rates could create herd immunity. Those estimates were based on calculations made with the original version of the virus and are no longer correct now that it has mutated, the New York Times reported.
Now, University of Florida researchers estimate around 80% of Floridians have been infected with omicron when taking into account people who may have been infected but not tested positive. Could this end the pandemic?
Probably not, said Tom Hladish, a research scientist in the University of Florida’s Department of Biology and Emerging Pathogens Institute and co-creator of the university’s omicron model, which provided the 80% estimate. He said as the pandemic progressed, scientists learned herd immunity isn’t going to stop COVID-19 surges. The public should stop focusing on herd immunity and instead focus on disease severity, he said.
“I understand why people want to talk about whether we are at some point going to have so much immunity in the population that COVID won’t be a problem anymore. I think that the sane answer is that’s never going to happen,” said Hladish. “A reasonable hope is that we will have enough immunity and enough tools for dealing with COVID that it’s not going to be so scary anymore.”
Why isn’t herd immunity possible for COVID-19?
The U.S. has successfully used herd immunity to fight diseases such as measles, so it wasn’t a wild dream at first, Hladish said. This hope hinged on the idea that immunity from COVID-19 vaccines could be as effective as measles vaccines, and last as long, allowing a sustained low level of transmission; scientists knew eradication was never realistic, he added.
After COVID-19 vaccinations became available to Americans in 2021, it became clear that herd immunity wasn’t a realistic target for this specific virus. The world wasn’t vaccinating enough people, and even if everyone got vaccinated, immunity against reinfection fades over time even though vaccinations protect against severe infection. Herd immunity couldn’t be a one-and-done goal. It would need to be refreshed with regular booster shots or exposure. Omicron then demonstrated that COVID-19’s constant mutations can produce variants that bypass vaccines and previous immunity, Hladish said. He predicts more infectious variants will emerge.
“To a large extent, the general public has been having the wrong conversation about this,” he said.
Fauci, in a May 2021 interview with the New York Times, acknowledged that people may have misunderstood what herd immunity could mean.
“People were getting confused and thinking you’re never going to get the infections down until you reach this mystical level of herd immunity, whatever that number is,” he said. “That’s why we stopped using herd immunity in the classic sense … I’m saying: Forget that for a second. You vaccinate enough people, the infections are going to go down.”
A realistic goal now is that vaccinations help provide a chance at a controlled but still present virus, said Tom Unnasch, a professor at the University of South Florida’s College of Public Health.
Unnasch said there are multiple types of immunity: one prevents you from reinfection with COVID-19. This type, created by antibodies, is highest after a shot or infection, then fades over time, he said.
But infection or vaccination creates other types of immunity that help prevent the virus from becoming severe, caused by T cells or memory B cells. This type of immunity is long-lasting. As more people get infected, he thinks more people will acquire T cells that work against COVID-19, which will thus protect them from severe infection.
“I think … people are going to start to see their immunity wane, and then they’ll get the infection again, but the T cells are going to kick in because they last a really long time,” Unnasch said. “It could be like a cold or flu.”
Unnasch hopes to see a future where we vaccinate, wash our hands more, and stay home while sick during a COVID-19 surge — just as we do during flu season. Influenza is still a serious disease. The flu killed 3,195 Floridians from 2019 to 2020, according to the Florida Department of Health. The flu doesn’t kill 66,000 Floridians in fewer than two years as COVID-19 did.
If we get lucky, the virus could evolve to be milder over time, too, he added. This is in no way guaranteed, according to an AP News article that provides examples of viruses that have evolved to become deadlier, such as those that develop drug-resistant variants.
Impacts of the omicron surge
There’s not enough evidence for conclusions, but people may have omicron-specific immunity for a limited time after infection, said Melanie Ott, a researcher at the nonprofit biomedical research organization Gladstone Institutes.
Ott and her colleagues tested various COVID-19 variants using blood from mice and found that omicron seemed to provide omicron-specific immunity, but not immunity against different variants such as delta. She thinks this could be because omicron is very different from past strains of COVID-19.
Ott said this suggests that Florida’s population may not see another omicron wave for a bit, but COVID-19 isn’t out of the picture.
Vaccination could help. If someone gets vaccinated and gets omicron that person can get “super immunity” to all existing variants, her study suggested.
“I would recommend to [everyone] who had omicron, still get a vaccination, at least one shot to make sure that they take the full benefit of that omicron infection,” she said.
Impacts of technology
The virus may also become less of a threat as doctors and scientists get better at treating it.
At the beginning of the pandemic, hospitals were unprepared, said Dr. Victor Herrera, chief medical officer and infectious disease specialist at AdventHealth Orlando.
“It really felt like driving a car in the middle of the night with no lights,” he said.
AdventHealth has since learned how to track signals in the community, such as its Centra Care urgent care positivity rate, to predict when a surge of COVID-19 patients is coming. This gives the hospital system time to gather supplies such as tests and medications and mobilize its workforce.
“Nobody knows what’s going to happen in the next chapter of the pandemic, but what I will say is … we are better prepared than ever to respond to a surge,” Herrera said. “I feel optimistic about the future.”
That being said, Floridians still need to try to avoid spreading the disease through measures such as vaccination and masks. The time of mild COVID-19, if it comes, is not here yet.
“We are still at that stage where it is circulating, it is making people sick, people end up in the hospital. We are still in the middle of it,” he concluded.
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