Why doesn’t the US consider natural immunity?

key takeaways

  • Some data suggest that people who have recovered from COVID-19 may be as protected from future infections as those who have been vaccinated.
  • At this point in the pandemic, validating an infection and counting it in an individual’s vaccine dose may be logically overcomplicated.
  • Public health leaders insist that vaccination is the best way to prevent infection from the virus.

From the early days of a COVID-19 vaccine rollout, the question of whether prior infection should count as the equivalent of a dose of vaccine has arisen and resurfaced in both the scientific and political circles.

Countries such as Israel, Canada, and the United Kingdom consider past infections to be an individual’s immune status. Some experts also point to growing evidence that immune protection against natural infection is at least as protective as vaccination.

But in the U.S., immunity status is entirely dependent on vaccination. There is no indication of where to recover from a previous infection on the vaccine card. Many agencies and employers require workers, students or visitors to be fully vaccinated and sometimes boosted. In trying to boost vaccination rates, the White House has repeatedly expressed frustration with those who refuse to get vaccinated.

Still, many people in the United States are developing mixed immunity, a combination of vaccination and infection.

CDC: Previous COVID-19 infection prevents Delta

According to CDC estimates, as of September 2021, more than 146 million people in the United States (more than 44% of the country’s population) have been infected with COVID-19 since the pandemic began. That percentage could be higher during a nationwide surge in cases caused by the Omicron variant.

With recoveries rising and data emerging on the persistence of natural immunity, should the U.S. view people as immunized or non-immunized, not vaccinated or unvaccinated?

Vaccines are standardized and more reliable than natural immunity, said Peter Chin-Hong, MD, professor of infectious diseases at the University of California, San Francisco.

“We know what to expect based on the experience of millions of vaccinated people and thousands of people now, and these trials are really tightly controlled,” Chin-Hong told VigorTip.

What is the difference between infection antibodies and vaccines?

Consider the case of natural immunity

The CDC maintains that people should be vaccinated against COVID-19 regardless of whether they have been previously infected, and says the level of protection against natural immunity may vary depending on the severity of the disease, age and time since infection. “There is currently no test available that can reliably determine whether a person is protected from infection,” the CDC said.

In discussions of immunity, the focus often falls on the importance of antibodies. At the same time, memory T cells and B cells are often overlooked. Once these antiviral cells are ready to recognize the invader—whether by vaccination or infection—they can wake up defenses against subsequent viral infections.

Antibodies are naturally cleared from the blood after the body has successfully fought off an infection. T cells and B cells stay for months, sometimes years or longer, ready to make new antibodies and attack future antigens.

A study published in a journal science The 2021 study showed that antibodies remained relatively stable for at least six months after infection with COVID-19, and that participants had more virus-specific B cells six months after infection than one month later.

In an investigative article published british medical journalsome experts believe that natural immunity should be considered as protective as vaccine-based immunity.

A preprint study in Israel found that people who recovered from COVID-19 fared better with both symptoms and severe COVID-19 than people who never had the vaccine. A preprint study from another group of researchers in Israel found that people who recovered from COVID-19 for three months were as protected from reinfection and severe consequences as those who were vaccinated. (Keep in mind that preprint research has not been peer-reviewed by outside experts.)

While the data underscore the capabilities of the body’s immune system, experts warn that the risk of contracting COVID-19 is high.

The surge in Omicron cases has prompted many to question whether it’s best to “end it.” It’s a dangerous approach that could lead to more hospitalizations and deaths, said Paul Gopfeldt, a professor of medicine and microbiology and director of the Alabama Vaccine Research Clinic.

Does Omicron increase the risk of reinfection with COVID-19?

“You don’t want people to go out and get infected thinking that’s how they’re going to be protected,” Goepfert told VigorTip. “You’re going to get a lot of people, and they’re going to get very sick like this, and some people are going to die.”

Most of the data showing antibody persistence was collected before the Omicron variant became dominant in the U.S. According to a preprint of a December study in South Africa, the risk of reinfection with Omicron was more than three times higher than with previous variants.

In addition, there is little data on how well infection with one variant, such as Delta, affects other variants.

Immune responses vary among naturally infected individuals

The caveat with natural immunity is that not all infections stimulate the immune system equally.

Generally, the severity of the disease determines a person’s antibody levels. For example, a person with a high fever for several days may produce more antibodies to the virus than someone with only a scratchy throat.

COVID-19 antibodies only last about 3 months, study finds

But that wasn’t always the case, Goepfert said. In a recent study, Goepfert’s team found that despite developing symptoms during the infection, 36 percent of participants who tested positive for COVID-19 produced few antibodies.

“I know a lot of people who are testing their antibodies after being infected and say, ‘Okay, I have these antibodies, so I’m fine.’ But we know that’s not necessarily the case,” Goepfert said.

FDA: Don’t use antibody tests to check if your COVID vaccine is working

Large amounts of antibodies are key to producing a good immune response, but scientists don’t yet have an easy way to tell the level of antibodies a person needs to protect against the consequences of a serious infection.

Furthermore, antibody levels are only part of the equation. Knowing a person’s T cell and B cell levels can provide key information about their immune protection against reinfection. A study of symptomatic and asymptomatic COVID-19 cases found similar levels of T cells in both groups, even with weakened antibodies.

However, testing T cells can be difficult – there is only one commercially available test.

Because immune responses to infection can be so different and antibody tests are relatively difficult to obtain, health officials continue to tout vaccination as the surest way to boost the body’s immune system against COVID-19.

These vaccines have proven time and time again to be highly effective in preventing the severe consequences of COVID-19 and greatly reduce the risk of infection and transmission.

timing matters

In order for a vaccine or infection to best stimulate the immune system, there must be a period of rest during which antibodies can be cleared from the blood. When a new dose of antigen is introduced, the immune cells are awakened again and perform another exercise to protect the body from the attacker.

“The more you alert the enemy’s immune system, the better it will perform in the future,” said Jin Hong, who specializes in infectious diseases.

People are eligible for booster shots five months or more after completing their primary treatment, the CDC said. Vaccination and booster programs are designed to boost the immune system when antibody levels drop in most people.

On the other hand, natural immunity does not adhere to a set schedule. It is impossible to know when a person will become infected, so the immune boost that comes with an infection may not be the best time.

Will the fourth COVID-19 vaccine prevent Omicron?

For example, a person receiving a two-dose regimen on a normal schedule could become infected a month after the second dose. In this case, their antibody levels may not have a chance to wane and reactivate, meaning the individual won’t get much of a boost.

If a person becomes infected later — say six months after the second injection — Goepfert said they may wait until the next surge to get a boost.

While it’s not unsafe to get a booster shot soon after recovering from COVID-19, some people experience more serious side effects and the vaccine’s effectiveness may be reduced.

“You can’t be activated by the same thing over and over again — your body has some sort of defense mechanism or regulatory mechanism that works against it,” Goepfert said.

But Jinhong advises not to wait more than three months after recovery to get a booster dose. Recovery from COVID-19 can only be considered equivalent to a dose of vaccine, or possibly less. People who are naturally infected but not vaccinated may not be able to prevent reinfection or spread the virus to their community, he added.

Already complex deployment

U.S. health officials have made vaccine-focused recommendations and mandates, opting for vetted vaccinations over antibody tests or accepting PCR test results as proof of immunity.

“Do we have systems in place to understand and verify documented infections? If we want to, we probably can. It might be logically easier to look at the card and look at the lot, date and vaccine to verify exposure,” Chin-Hong said.

With the popularity of Omicron and other variants likely to emerge in the future, an easily editable mRNA vaccine could be the key to a more targeted approach to immunization than natural immunization can provide. Pfizer, Moderna and Johnson & Johnson are developing Omicron-specific vaccines. Pfizer said it began a Phase 1 clinical trial last week.

Can mRNA boosters prevent Omicron?

“Vaccines can keep up with the development of variants, but natural immunity can’t,” Goepfert said.

Mixed immunity may help in the long run

Chin-Hong said that mixed immunity — a combination of natural and vaccine-induced immunity — is the “holy grail” of immune responses, both at the individual level and in larger populations.

Due to the high incidence in the United States, most people likely have some degree of natural immunity to COVID-19. Coupled with relatively large vaccination coverage, the country is developing a mixed immune system.

In the future, when the disease becomes endemic, Chin-Hong said, documentation showing some prior infection or antibody status may be sufficient to demonstrate immunity.

‘Flurona’ isn’t new: COVID-flu coinfection explained

“My prediction is that we’re going to drop off Omicron and this country quickly and hopefully the world will have more immunity. When the dust settles, people will feel more relaxed about what it means to relax some immunity,” Chin-Hong said. .

Until then, he said, “we want to maximize the protection of people in the best way we know.”

what does this mean to you

Experts warn against knowingly contracting COVID-19, which could have serious short- and long-term health consequences. Getting vaccinated and receiving booster immunizations is the best way to protect yourself and others from disease.

The information in this article is current as of the date listed, which means that you may have updated information as you read this article. For the latest updates on COVID-19, visit our Coronavirus news page.