Antibody Testing Alone is Not the Key to Re-Opening Society
[Editor's Note: We asked experts from different specialties to weigh in on a timely Big Question: "How should immunity testing play a role in re-opening society?" Below, a virologist offers her perspective.]
With the advent of serology testing and increased emphasis on "re-opening" America, public health officials have begun considering whether or not people who have recovered from COVID-19 can safely re-enter the workplace.
"Immunity certificates cannot certify what is not known."
Conventional wisdom holds that people who have developed antibodies in response to infection with SARS-CoV-2, the coronavirus that causes COVID-19, are likely to be immune to reinfection.
For most acute viral infections, this is generally true. However, SARS-CoV-2 is a new pathogen, and there are currently many unanswered questions about immunity. Can recovered patients be reinfected or transmit the virus? Does symptom severity determine how protective responses will be after recovery? How long will protection last? Understanding these basic features is essential to phased re-opening of the government and economy for people who have recovered from COVID-19.
One mechanism that has been considered is issuing "immunity certificates" to individuals with antibodies against SARS-CoV-2. These certificates would verify that individuals have already recovered from COVID-19, and thus have antibodies in their blood that will protect them against reinfection, enabling them to safely return to work and participate in society. Although this sounds reasonable in theory, there are many practical reasons why this is not a wise policy decision to ease off restrictive stay-home orders and distancing practices.
Too Many Scientific Unknowns
Serology tests measure antibodies in the serum—the liquid component of blood, which is where the antibodies are located. In this case, serology tests measure antibodies that specifically bind to SARS-CoV-2 virus particles. Usually when a person is infected with a virus, they develop antibodies that can "recognize" that virus, so the presence of SARS-CoV-2 antibodies indicates that a person has been previously exposed to the virus. Broad serology testing is critical to knowing how many people have been infected with SARS-CoV-2, since testing capacity for the virus itself has been so low.
Tests for the virus measure amounts of SARS-CoV-2 RNA—the virus's genetic material—directly, and thus will not detect the virus once a person has recovered. Thus, the majority of people who were not severely ill and did not require hospitalization, or did not have direct contact with a confirmed case, will not test positive for the virus weeks after they have recovered and can only determine if they had COVID-19 by testing for antibodies.
In most cases, for most pathogens, antibodies are also neutralizing, meaning they bind to the virus and render it incapable of infecting cells, and this protects against future infections. Immunity certificates are based on the assumption that people with antibodies specific for SARS-CoV-2 will be protected against reinfection. The problem is that we've only known that SARS-CoV-2 existed for a little over four months. Although studies so far indicate that most (but not all) patients with confirmed COVID-19 cases develop antibodies, we don't know the extent to which antibodies are protective against reinfection, or how long that protection will last. Immunity certificates cannot certify what is not known.
The limited data so far is encouraging with regard to protective immunity. Most of the patient sera tested for antibodies show reasonable titers of IgG, the type of antibodies most likely to be neutralizing. Furthermore, studies have shown that these IgG antibodies are capable of neutralizing surrogate viruses as well as infectious SARS-CoV-2 in laboratory tests. In addition, rhesus monkeys that were experimentally infected with SARS-CoV-2 and allowed to recover were protected from reinfection after a subsequent experimental challenge. These data tentatively suggest that most people are likely to develop neutralizing IgG, and protective immunity, after being infected by SARS-CoV-2.
However, not all COVID-19 patients do produce high levels of antibodies specific for SARS-CoV-2. A small number of patients in one study had no detectable neutralizing IgG. There have also been reports of patients in South Korea testing PCR positive after a prior negative test, indicating reinfection or reactivation. These cases may be explained by the sensitivity of the PCR test, and no data have been produced to indicate that these cases are genuine reinfection or recurrence of viral infection.
Complicating matters further, not all serology tests measure antibody titers. Some rapid serology tests are designed to be binary—the test can either detect antibodies or not, but does not give information about the amount of antibodies circulating. Based on our current knowledge, we cannot be certain that merely having any level of detectable antibodies alone guarantees protection from reinfection, or from a subclinical reinfection that might not cause a second case of COVID-19, but could still result in transmission to others. These unknowns remain problematic even with tests that accurately detect the presence of antibodies—which is not a given today, as many of the newly available tests are reportedly unreliable.
A Logistical and Ethical Quagmire
While most people are eager to cast off the isolation of physical distancing and resume their normal lives, mere desire to return to normality is not an indicator of whether those antibodies actually work, and no certificate can confer immune protection. Furthermore, immunity certificates could lead to some complicated logistical and ethical issues. If antibodies do not guarantee protective immunity, certifying that they do could give antibody-positive people a false sense of security, causing them to relax infection control practices such as distancing and hand hygiene.
"We should not, however, place our faith in assumptions and make return to normality contingent on an arbitrary and uninformative piece of paper."
Certificates could be forged, putting susceptible people at higher exposure risk. It's not clear who would issue them, what they would entitle the bearer to do or not do, or how certification would be verified or enforced. There are many ways in which such certificates could be used as a pretext to discriminate against people based on health status, in addition to disability, race, and socioeconomic status. Tracking people based on immune status raises further concerns about privacy and civil rights.
Rather than issuing documents confirming immune status, we should instead "re-open" society cautiously, with widespread virus and serology testing to accurately identify and isolate infected cases rapidly, with immediate contact tracing to safely quarantine and monitor those at exposure risk. Broad serosurveillance must be coupled with functional assays for neutralization activity to begin assessing how protective antibodies might actually be against SARS-CoV-2 infection. To understand how long immunity lasts, we should study antibodies, as well as the functional capabilities of other components of the larger immune system, such as T cells, in recovered COVID-19 patients over time.
We should not, however, place our faith in assumptions and make return to normality contingent on an arbitrary and uninformative piece of paper. Re-opening society, the government, and the economy depends not only on accurately determining how many people have antibodies to SARS-CoV-2, but on a deeper understanding of how those antibodies work to provide protection.
Tiny, Injectable Robots Could Be the Future of Brain Treatments
In the 1966 movie "Fantastic Voyage," actress Raquel Welch and her submarine were shrunk to the size of a cell in order to eliminate a blood clot in a scientist's brain. Now, 55 years later, the scenario is becoming closer to reality.
California-based startup Bionaut Labs has developed a nanobot about the size of a grain of rice that's designed to transport medication to the exact location in the body where it's needed. If you think about it, the conventional way to deliver medicine makes little sense: A painkiller affects the entire body instead of just the arm that's hurting, and chemotherapy is flushed through all the veins instead of precisely targeting the tumor.
"Chemotherapy is delivered systemically," Bionaut-founder and CEO Michael Shpigelmacher says. "Often only a small percentage arrives at the location where it is actually needed."
But what if it was possible to send a tiny robot through the body to attack a tumor or deliver a drug at exactly the right location?
Several startups and academic institutes worldwide are working to develop such a solution but Bionaut Labs seems the furthest along in advancing its invention. "You can think of the Bionaut as a tiny screw that moves through the veins as if steered by an invisible screwdriver until it arrives at the tumor," Shpigelmacher explains. Via Zoom, he shares the screen of an X-ray machine in his Culver City lab to demonstrate how the half-transparent, yellowish device winds its way along the spine in the body. The nanobot contains a tiny but powerful magnet. The "invisible screwdriver" is an external magnetic field that rotates that magnet inside the device and gets it to move and change directions.
The current model has a diameter of less than a millimeter. Shpigelmacher's engineers could build the miniature vehicle even smaller but the current size has the advantage of being big enough to see with bare eyes. It can also deliver more medicine than a tinier version. In the Zoom demonstration, the micorobot is injected into the spine, not unlike an epidural, and pulled along the spine through an outside magnet until the Bionaut reaches the brainstem. Depending which organ it needs to reach, it could be inserted elsewhere, for instance through a catheter.
"The hope is that we can develop a vehicle to transport medication deep into the body."
Imagine moving a screw through a steak with a magnet — that's essentially how the device works. But of course, the Bionaut is considerably different from an ordinary screw: "At the right location, we give a magnetic signal, and it unloads its medicine package," Shpigelmacher says.
To start, Bionaut Labs wants to use its device to treat Parkinson's disease and brain stem gliomas, a type of cancer that largely affects children and teenagers. About 300 to 400 young people a year are diagnosed with this type of tumor. Radiation and brain surgery risk damaging sensitive brain tissue, and chemotherapy often doesn't work. Most children with these tumors live less than 18 months. A nanobot delivering targeted chemotherapy could be a gamechanger. "These patients really don't have any other hope," Shpigelmacher says.
Of course, the main challenge of the developing such a device is guaranteeing that it's safe. Because tissue is so sensitive, any mistake could risk disastrous results. Over the past four years, Bionaut has tested its technology in dozens of healthy sheep and pigs with no major adverse effects. Sheep make a good stand-in for humans because their brains and spines are similar to ours.
The Bionaut device is about the size of a grain of rice.
Bionaut Labs
"As the Bionaut moves through brain tissue, it creates a transient track that heals within a few weeks," Shpigelmacher says. The company is hoping to be the first to test a nanobot in humans. That could happen as early as 2023, Shpigelmacher says.
Once the technique has been perfected, further applications could include addressing other kinds of brain disorders that are considered incurable now, such as Alzheimer's or Huntington's disease. "Microrobots could serve as a bridgehead, opening the gateway to the brain and facilitating precise access of deep brain structure – either to deliver medication, take cell samples or stimulate specific brain regions," Shpigelmacher says.
Robot-assisted hybrid surgery with artificial intelligence is already used in state-of-the-art surgery centers, and many medical experts believe that nanorobotics will be the instrument of the future. In 2016, three scientists were awarded the Nobel Prize in Chemistry for their development of "the world's smallest machines," nano "elevators" and minuscule motors. Since then, the scientific experiments have progressed to the point where applicable devices are moving closer to actually being implemented.
Bionaut's technology was initially developed by a research team lead by Peer Fischer, head of the independent Micro Nano and Molecular Systems Lab at the Max Planck Institute for Intelligent Systems in Stuttgart, Germany. Fischer is considered a pioneer in the research of nano systems, which he began at Harvard University more than a decade ago. He and his team are advising Bionaut Labs and have licensed their technology to the company.
"The hope is that we can develop a vehicle to transport medication deep into the body," says Max Planck scientist Tian Qiu, who leads the cooperation with Bionaut Labs. He agrees with Shpigelmacher that the Bionaut's size is perfect for transporting medication loads and is researching potential applications for even smaller nanorobots, especially in the eye, where the tissue is extremely sensitive. "Nanorobots can sneak through very fine tissue without causing damage."
In "Fantastic Voyage," Raquel Welch's adventures inside the body of a dissident scientist let her swim through his veins into his brain, but her shrunken miniature submarine is attacked by antibodies; she has to flee through the nerves into the scientist's eye where she escapes into freedom on a tear drop. In reality, the exit in the lab is much more mundane. The Bionaut simply leaves the body through the same port where it entered. But apart from the dramatization, the "Fantastic Voyage" was almost prophetic, or, as Shpigelmacher says, "Science fiction becomes science reality."
Every weekend since January, pediatrician Cora Collette Breuner has volunteered to give the COVID-19 vaccine to individuals from age 12 to 96 in an underserved community in Washington state.
Even though the COVID-19 vaccines have been shown to be incredibly safe and effective, there's still quite a bit of hesitancy among parents to vaccinate their teenage children, says Breuner, an adolescent medicine specialist at Seattle Children's Hospital and a past chair of the American Academy of Pediatrics' Committee on Adolescence. "They have questions and they have questions," she says.
Breuner patiently answers them all. Even then, parents—who have the final say in whether their child gets the vaccine—may be reluctant to sign off on it.
In 41 states, parents must consent for minors under age 18 to receive a COVID-19 vaccine. One state—Nebraska—requires parental consent for individuals under age 19, according to the Kaiser Family Foundation. Healthcare workers can't legally give teens COVID-19 vaccines otherwise. In a May report, the nonprofit healthcare organization highlights that from a legal perspective, "the landscape may be shifting slightly as more jurisdictions seek to encourage vaccination of young people."
Meanwhile, as the Delta variant creates a new surge in cases, some ethicists and pediatricians argue that state laws should be amended or loosened to allow minors to consent to COVID-19 vaccination on their own, without the need for parental permission.
"COVID-19 has killed millions of people around the world and disrupted the global economy," says pediatrician John Lantos. "It's a global catastrophe that requires special rules."
There are compelling arguments in favor of letting minors consent on their own, says Robyn Shapiro, a health care lawyer and a bioethicist in the Milwaukee area. "By that, I mean they're either old enough or they're evaluated in such a way that they have sufficient understanding of what they're agreeing to."
Shapiro and other ethicists argue that teens are perfectly capable of giving "informed consent"—a key principle in ethics that means fully understanding the benefits and risks of a medical intervention. To give informed consent, a person must be able to process that information in line with their own values. Only then can they make an autonomous choice and sign a consent form, Shapiro says.
Most states already have laws permitting minors to consent to testing and treatments related to sexually transmitted diseases, birth control, behavioral health, and substance abuse. It wouldn't be that much of a stretch to add COVID-19 vaccination to the list, Shapiro says. New Jersey and New York have introduced bills to let teens as young as 14 to consent to getting the COVID-19 vaccine and Minnesota has proposed a bill to allow children as young as 12 to give consent.
With any medical test or intervention, doctors often wrestle with how to best involve teens in conversations about their own health care, says John Lantos, a pediatrician and director of the Bioethics Center at Children's Mercy Kansas City.
"Most bioethicists would say that [teens] should be included to the degree that they have decision-making capacity," he says. "In most cases, that means including them in discussions with their parents in trying to achieve consensus about what the best choice may be."
COVID-19 vaccination also presents a unique circumstance, Lantos notes. It raises the question: Should teens have greater decisional authority because it's a public health emergency? In his opinion, the answer is yes. "COVID-19 has killed millions of people around the world and disrupted the global economy," says pediatrician Lantos. "It's a global catastrophe that requires special rules."
In North Carolina, state legislators are moving to do the opposite. State law currently allows those under 18 to make vaccination decisions on their own, but on Aug. 5, North Carolina's General Assembly approved a Republican-sponsored bill requiring parental consent for 12- to 17-year-olds to get a COVID-19 vaccine.
Kyle Brothers, a pediatrician in Louisville, Kentucky, says it's "ethically justifiable" for states to permit adolescents, especially those on the verge of adulthood, to consent to COVID-19 vaccination and other straightforward medical care.
In many cases, 16- and 17-year-old adolescents are capable of making well-informed decisions, says Brothers, a member of the American Academy of Pediatrics' Section on Bioethics. "The problem is, the law tends not to have that level of nuance," he adds. "We know in the real world that maturing and developing the ability to make decisions is a continuous process, but the law sets a bright line at age 18."
Lacking parental consent, some defiant teens are researching avenues to get vaccinated without their mom's or dad's knowledge. They may have turned to VaxTeen.org, a site operated by a Los Angeles teenager that provides information on consent laws by state.
If parents are wavering on the decision to give consent, Breuner recommends that they speak with a trusted healthcare provider about their specific concerns. These kinds of dialogues often can clarify lingering worries and may help drive up consent rates for teen vaccination.
Vaccine-hesitant parents should hear out their teens who wish to be vaccinated. Teenagers have their own opinions and belief systems, and parents should respect their child's choice to be vaccinated if they wish, considering the minimal risk of harm and the significant benefit to society as a whole.
George J. Annas, professor and director at the Center for Health Law, Ethics & Human Rights at Boston University, says parents have a legal obligation to provide their children with necessary medical treatment, or they could be found guilty of child neglect. The circumstances vary, but in the face of unrelenting COVID-19, he says parents have an ethical duty to consent to teens' vaccination because "the disease is rampant and children are dying."