As COVID-19 rapidly expanded throughout the world in April 2020, many in the biomedical technology community voiced significant concerns about the lack of available diagnostic tests. At that time, testing for SARS-CoV-2, the coronavirus that causes COVID-19, was conducted exclusively in clinical laboratories by order of a health-care provider. “Over the counter” (OTC) tests did not exist, and low complexity point of care (POC) platforms were rare. Fewer than 8 million tests were performed in the U.S. that month, and it was clear that we needed a radical transformation to make tests faster and more accessible.
By February 2022, driven by the Omicron variant surge, U.S. capacity had increased to a new record of more than 1.2 billion tests in a single month. Remarkably, the overwhelming majority of these—more than 85 percent—were “rapid tests” conducted in home and POC settings.
The story behind this practice-changing, “test-at-home” transformation is deeply rooted in technologic and manufacturing innovation. The NIH’s National Institute of Biomedical Imaging and Bioengineering (NIBIB), working collaboratively with multiple partners across NIH, government, academia, and the private sector, has been privileged to play a leading role in this effort via the Rapid Acceleration of Diagnostics (RADx®) initiative. On this two-year anniversary of RADx, we take a brief look back at its formation, impact, and potential for future growth.
On April 24, 2020, Congress recognized that testing was an urgent national need and appropriated $1.5 billion to NIH via an emergency supplement . The goal was to substantially increase the number, type, and availability of diagnostic tests in only five to six months. Since the “normal” commercialization cycle for this type of diagnostic technology is typically more than five years, we needed an entirely new approach . . . fast.
The RADx initiative was launched just five days after that challenging Congressional directive . Four NIH RADx programs were eventually created to support technology development and delivery, with the goal of matching test performance with community needs .The first two programs, RADx Tech and RADx Advanced Technology Platforms (ATP), were developed by NIBIB and focused on innovation for rapidly creating, scaling up, and deploying new technologies.
RADx Tech is built around NIBIB’s Point of Care Technologies Research Network (POCTRN) and includes core activities for technology review, test validation, clinical studies, regulatory authorization, and test deployment. Overall, the RADx Tech network includes approximately 900 participants from government, academia, and the private sector with unique capabilities and resources designed to decrease inherent risk and guide technologies from design and development to fully disseminated commercial products.
At the core of RADx Tech operations is the “innovation funnel” rapid review process, popularized as a shark tank . A total of 824 complete applications were submitted during two open calls in a four-month period, beginning April 2020 and during a one-month period in June 2021. Forty-seven projects received phase 1 funding to validate and lower the inherent risk of developing these technologies. Meanwhile, 50 companies received phase 2 contracts to support FDA authorization studies and manufacturing expansion 
Beyond test development, RADx Tech has evolved to become a key contributor to the U.S. COVID-19 response. The RADx Independent Test Assessment Program (ITAP) was launched in October 2021 to accelerate regulatory authorization of new tests as a joint effort with the Food and Drug Administration (FDA) . The ITAP acquires analytical and clinical performance data and works closely with FDA and manufacturers to shave weeks to months off the time it normally takes to receive Emergency Use Authorization (EUA).
The RADx Tech program also created a Variant Task Force to monitor the performance of tests against each new coronavirus “variant of concern” that emerges. This helps to ensure that marketed tests continue to remain effective. Other innovative RADx Tech projects include Say Yes! Covid Test, the first online free OTC test distribution program, and Project Rosa, which conducts real-time variant tracking across the country .
RADx Tech, by any measure, has exceeded even the most-optimistic expectations. In two years, RADx Tech-supported companies have received 44 EUAs and added approximately 2 billion tests and test products to the U.S. capacity. These remarkable numbers have steadily increased from more than16 million tests in September 2020, just five months after the program was established .
RADx Tech has also made significant contributions to the distribution of 1 billion free OTC tests via the government site, COVID.gov/tests. It has also provided critical guidance on serial testing and variants that have improved test performance and changed regulatory practice [9,10]. In addition, the RADx Mobile Application Reporting System (RADx MARS) reduces barriers to test reporting and test-to-treat strategies’ The latter offers immediate treatment options via telehealth or a POC location whenever a positive test result is reported. Finally, the When to Test website provides critical guidance on when and how to test for individuals, groups, and communities.
As we look to the future, RADx Tech has enormous potential to impact the U.S. response to other pathogens, diseases, and future pandemics. Major challenges going forward include improving home tests to work as well as lab platforms and building digital health networks for capturing and reporting test results to public health officials .
A recent editorial published in the journal Nature Biotechnology noted, “RADx has spawned a phalanx of diagnostic products to market in just 12 months. Its long-term impact on point of care, at-home, and population testing may be even more profound .” We are now poised to advance a new wave of precision medicine that’s led by innovative diagnostic technologies. It represents a unique opportunity to emerge stronger from the pandemic and achieve long-term impact.
 NIH mobilizes national innovation initiative for COVID-19 diagnostics, NIH news release, April 29, 2020.
 Rapid scaling up of Covid-19 diagnostic testing in the United States—The NIH RADx Initiative. Tromberg BJ, Schwetz TA, Pérez-Stable EJ, Hodes RJ, Woychik RP, Bright RA, Fleurence RL, Collins FS. N Engl J Med. 2020 Sep 10;383(11):1071-1077.
 We need more covid-19 tests. We propose a ‘shark tank’ to get us there. Alexander L. and Blunt R., Washington Post, April 20, 2020.
 RADx® Tech/ATP dashboard, National Institute of Biomedical Imaging and Bioengineering, NIH.
 New HHS actions add to Biden Administration efforts to increase access to easy-to-use over-the-counter COVID-19 tests. U.S. Department of Health and Human Services Press Office, October 25, 2021.
 A method for variant agnostic detection of SARS-CoV-2, rapid monitoring of circulating variants, detection of mutations of biological significance, and early detection of emergent variants such as Omicron. Lai E, et al. medRxiV preprint, January 9, 2022.
 Longitudinal assessment of diagnostic test performance over the course of acute SARS-CoV-2 infection. Smith RL, et al. J Infect Dis. 2021 Sep 17;224(6):976-982.
 Comparison of rapid antigen tests’ performance between Delta (B.1.61.7; AY.X) and Omicron (B.1.1.529; BA1) variants of SARS-CoV-2: Secondary analysis from a serial home self-testing study. Soni A, et al. MedRxiv preprint, March 2, 2022.
 Reporting COVID-19 self-test results: The next frontier. Health Affairs, Juluru K., et al. Health Affairs, February 11, 2022.
 Radical solutions. Nat Biotechnol. 2021 Apr;39(4):391.
Get Free At-Home COVID Tests (COVID.gov)
When to Test (Consortia for Improving Medicine with Innovation & Technology, Boston)
RADx Programs (NIH)
RADx® Tech and ATP Programs (National Institute of Biomedical Imaging and Biomedical Engineering/NIH)
[Note: Acting NIH Director Lawrence Tabak has asked the heads of NIH’s Institutes and Centers (ICs) to contribute occasional guest posts to the blog to highlight some of the interesting science that they support and conduct. This is the eighth in the series of NIH IC guest posts that will run until a new permanent NIH director is in place.]
Posted on by Lawrence Tabak, D.D.S., Ph.D.
More than 215 million people in the United States are now fully vaccinated against the SARS-CoV-2 virus responsible for COVID-19 . More than 40 percent—more than 94 million people—also have rolled up their sleeves for an additional, booster dose. Now, an NIH-funded study exploring how mRNA vaccines are performing over time comes as a reminder of just how important it will be to keep those COVID-19 vaccines up to date as coronavirus variants continue to circulate.
The results, published in the journal Science Translational Medicine, show that people who received two doses of either the Pfizer or Moderna COVID-19 mRNA vaccines did generate needed virus-neutralizing antibodies . But levels of those antibodies dropped considerably after six months, suggesting declining immunity over time.
The data also reveal that study participants had much reduced protection against newer SARS-CoV-2 variants, including Delta and Omicron. While antibody protection remained stronger in people who’d also had a breakthrough infection, even that didn’t appear to offer much protection against infection by the Omicron variant.
The new study comes from a team led by Shan-Lu Liu at The Ohio State University, Columbus. They wanted to explore how well vaccine-acquired immune protection holds up over time, especially in light of newly arising SARS-CoV-2 variants.
This is an important issue going forward because mRNA vaccines train the immune system to produce antibodies against the spike proteins that crown the surface of the SARS-CoV-2 coronavirus. These new variants often have mutated, or slightly changed, spike proteins compared to the original one the immune system has been trained to detect, potentially dampening the immune response.
In the study, the team collected serum samples from 48 fully vaccinated health care workers at four key time points: 1) before vaccination, 2) three weeks after the first dose, 3) one month after the second dose, and 4) six months after the second dose.
They then tested the ability of antibodies in those samples to neutralize spike proteins as a correlate for how well a vaccine works to prevent infection. The spike proteins represented five major SARS-CoV-2 variants. The variants included D614G, which arose very soon after the coronavirus first was identified in Wuhan and quickly took over, as well as Alpha (B.1.1.7), Beta (B.1.351), Delta (B.1.617.2), and Omicron (B.1.1.529).
The researchers explored in the lab how neutralizing antibodies within those serum samples reacted to SARS-CoV-2 pseudoviruses representing each of the five variants. SARS-CoV-2 pseudoviruses are harmless viruses engineered, in this case, to bear coronavirus spike proteins on their surfaces. Because they don’t replicate, they are safe to study without specially designed biosafety facilities.
At any of the four time points, antibodies showed a minimal ability to neutralize the Omicron spike protein, which harbors about 30 mutations. These findings are consistent with an earlier study showing a significant decline in neutralizing antibodies against Omicron in people who’ve received the initial series of two shots, with improved neutralizing ability following an additional booster dose.
The neutralizing ability of antibodies against all other spike variants showed a dramatic decline from 1 to 6 months after the second dose. While there was a marked decline over time after both vaccines, samples from health care workers who’d received the Moderna vaccine showed about twice the neutralizing ability of those who’d received the Pfizer vaccine. The data also suggests greater immune protection in fully vaccinated healthcare workers who’d had a breakthrough infection with SARS-CoV-2.
In addition to recommending full vaccination for all eligible individuals, the Centers for Disease Control and Prevention (CDC) now recommends everyone 12 years and up should get a booster dose of either the Pfizer or Moderna vaccines at least five months after completing the primary series of two shots . Those who’ve received the Johnson & Johnson vaccine should get a booster at least two months after receiving the initial dose.
While plenty of questions about the durability of COVID-19 immunity over time remain, it’s clear that the rapid deployment of multiple vaccines over the course of this pandemic already has saved many lives and kept many more people out of the hospital. As the Omicron threat subsides and we start to look forward to better days ahead, it will remain critical for researchers and policymakers to continually evaluate and revise vaccination strategies and recommendations, to keep our defenses up as this virus continues to evolve.
 COVID-19 vaccinations in the United States. Centers for Disease Control and Prevention. February 27, 2022.
 Neutralizing antibody responses elicited by SARS-CoV-2 mRNA vaccination wane over time and are boosted by breakthrough infection. Evans JP, Zeng C, Carlin C, Lozanski G, Saif LJ, Oltz EM, Gumina RJ, Liu SL. Sci Transl Med. 2022 Feb 15:eabn8057.
 COVID-19 vaccine booster shots. Centers for Disease Control and Prevention. Feb 2, 2022.
COVID-19 Research (NIH)
Shan-Lu Liu (The Ohio State University, Columbus)
NIH Support: National Institute of Allergy and Infectious Diseases; National Cancer Institute; National Heart, Lung, and Blood Institute; Eunice Kennedy Shriver National Institute of Child Health and Human Development
Posted on by Lawrence Tabak, D.D.S., Ph.D.
Since joining NIH, I’ve held a number of different leadership positions. But there is one position that thankfully has remained constant for me: lab chief. I run my own research laboratory at NIH’s National Institute of Dental and Craniofacial Research (NIDCR).
My lab studies a biochemical process called O-glycosylation. It’s fundamental to life and fascinating to study. Our cells are often adorned with a variety of carbohydrate sugars. O-glycosylation refers to the biochemical process through which these sugar molecules, either found at the cell surface or secreted, get added to proteins. The presence or absence of these sugars on certain proteins plays fundamental roles in normal tissue development and first-line human immunity. It also is associated with various diseases, including cancer.
Our lab recently joined a team of NIH scientists led by my NIDCR colleague Kelly Ten Hagen to demonstrate how O-glycosylation can influence SARS-CoV-2, the coronavirus that causes COVID-19, and its ability to fuse to cells, which is a key step in infecting them. In fact, our data, published in the journal Proceedings of the National Academy of Sciences, indicate that some variants, seem to have mutated to exploit the process to their advantage .
The work builds on the virus’s reliance on the spike proteins that crown its outer surface to attach to human cells. Once there, the spike protein must be activated to fuse and launch an infection. That happens when enzymes produced by our own cells make a series of cuts, or cleavages, to the spike protein.
The first cut comes from an enzyme called furin. We and others had earlier evidence that O-glycosylation can affect the way furin makes those cuts. That got us thinking: Could O-glycosylation influence the interaction between furin and the spike protein? The furin cleavage area of the viral spike was indeed adorned with sugars, and their presence or absence might influence spike activation by furin.
We also noticed the Alpha and Delta variants carry a mutation that removes the amino acid proline in a specific spot. That was intriguing because we knew from earlier work that enzymes called GALNTs, which are responsible for adding bulky sugar molecules to proteins, prefer prolines near O-glycosylation sites.
It also suggested that loss of proline in the new variants could mean decreased O-glycosylation, which might then influence the degree of furin cleavage and SARS-CoV-2’s ability to enter cells. I should note that the recent Omicron variant was not examined in the current study.
After detailed studies in fruit fly and mammalian cells, we demonstrated in the original SARS-CoV-2 virus that O-glycosylation of the spike protein decreases furin cleavage. Further experiments then showed that the GALNT1 enzyme adds sugars to the spike protein and this addition limits the ability of furin to make the needed cuts and activate the spike protein.
Importantly, the spike protein change found in the Alpha and Delta variants lowers GALNT1 activity, making it easier for furin to start its activating cuts. It suggests that glycosylation of the viral spike by GALNT1 may limit infection with the original virus, and that the Alpha and Delta variant mutation at least partially overcomes this effect, to potentially make the virus more infectious.
Building on these studies, our teams looked for evidence of GALNT1 in the respiratory tracts of healthy human volunteers. We found that the enzyme is indeed abundantly expressed in those cells. Interestingly, those same cells also express the ACE2 receptor, which SARS-CoV-2 depends on to infect human cells.
It’s also worth noting here that the Omicron variant carries the very same spike mutation that we studied in Alpha and Delta. Omicron also has another nearby change that might further alter O-glycosylation and cleavage of the spike protein by furin. The Ten Hagen lab is looking into these leads to learn how this region in Omicron affects spike glycosylation and, ultimately, the ability of this devastating virus to infect human cells and spread.
 Furin cleavage of the SARS-CoV-2 spike is modulated by O-glycosylation. Zhang L, Mann M, Syed Z, Reynolds HM, Tian E, Samara NL, Zeldin DC, Tabak LA, Ten Hagen KG. PNAS. 2021 Nov 23;118(47).
COVID-19 Research (NIH)
Kelly Ten Hagen (National Institute of Dental and Craniofacial Research/NIH)
Lawrence Tabak (NIDCR)
NIH Support: National Institute of Dental and Craniofacial Research
Posted on by Dr. Francis Collins
There’s been great concern about the new Omicron variant of SARS-CoV-2, the coronavirus that causes COVID-19. A major reason is Omicron has accumulated over 50 mutations, including about 30 in the spike protein, the part of the coronavirus that mRNA vaccines teach our immune systems to attack. All of these genetic changes raise the possibility that Omicron could cause breakthrough infections in people who’ve already received a Pfizer or Moderna mRNA vaccine.
So, what does the science show? The first data to emerge present somewhat encouraging results. While our existing mRNA vaccines still offer some protection against Omicron, there appears to be a significant decline in neutralizing antibodies against this variant in people who have received two shots of an mRNA vaccine.
However, initial results of studies conducted both in the lab and in the real world show that people who get a booster shot, or third dose of vaccine, may be better protected. Though these data are preliminary, they suggest that getting a booster will help protect people already vaccinated from breakthrough or possible severe infections with Omicron during the winter months.
Though Omicron was discovered in South Africa only last month, researchers have been working around the clock to learn more about this variant. Last week brought the first wave of scientific data on Omicron, including interesting work from a research team led by Alex Sigal, Africa Health Research Institute, Durban, South Africa .
In lab studies working with live Omicron virus, the researchers showed that this variant still relies on the ACE2 receptor to infect human lung cells. That’s really good news. It means that the therapeutic tools already developed, including vaccines, should generally remain useful for combatting this new variant.
Sigal and colleagues also tested the ability of antibodies in the plasma from 12 fully vaccinated individuals to neutralize Omicron. Six of the individuals had no history of COVID-19. The other six had been infected with the original variant in the first wave of infections in South Africa.
As expected, the samples showed very strong neutralization against the original SARS-CoV-2 variant. However, antibodies from people who’d been previously vaccinated with the two-dose Pfizer vaccine took a significant hit against Omicron, showing about a 40-fold decline in neutralizing ability.
This escape from immunity wasn’t complete. Indeed, blood samples from five individuals showed relatively good antibody levels against Omicron. All five had previously been infected with SARS-CoV-2 in addition to being vaccinated. These findings add to evidence on the value of full vaccination for protecting against reinfections in people who’ve had COVID-19 previously.
Also of great interest were the first results of the Pfizer study, which the company made available in a news release . Pfizer researchers also conducted laboratory studies to test the neutralizing ability of blood samples from 19 individuals one month after a second shot compared to 20 others one month after a booster shot.
These studies showed that the neutralizing ability of samples from those who’d received two shots had a more than 25-fold decline relative to the original virus. Together with the South Africa data, it suggests that the two-dose series may not be enough to protect against breakthrough infections with the Omicron variant.
In much more encouraging news, their studies went on to show that a booster dose of the Pfizer vaccine raised antibody levels against Omicron to a level comparable to the two-dose regimen against the original variant (as shown in the figure above). While efforts already are underway to develop an Omicron-specific COVID-19 vaccine, these findings suggest that it’s already possible to get good protection against this new variant by getting a booster shot.
Very recently, real-world data from the United Kingdom, where Omicron cases are rising rapidly, are providing additional evidence for how boosters can help. In a preprint , Andrews et. al showed the effectiveness of two shots of Pfizer mRNA vaccine trended down after four months to about 40 percent. That’s not great, but note that 40 percent is far better than zero. So, clearly there is some protection provided.
Most impressively (as shown in the figure from Andrews N, et al.) a booster substantially raised that vaccine effectiveness to about 80 percent. That’s not quite as high as for Delta, but certainly an encouraging result. Once again, these data show that boosting the immune system after a pause produces enhanced immunity against new viral variants, even though the booster was designed from the original virus. Your immune system is awfully clever. You get both quantitative and qualitative benefits.
It’s also worth noting that the Omicron variant mostly doesn’t have mutations in portions of its genome that are the targets of other aspects of vaccine-induced immunity, including T cells. These cells are part of the body’s second line of defense and are generally harder for viruses to escape. While T cells can’t prevent infection, they help protect against more severe illness and death.
It’s important to note that scientists around the world are also closely monitoring Omicron’s severity While this variant appears to be highly transmissible, and it is still early for rigorous conclusions, the initial research indicates this variant may actually produce milder illness than Delta, which is currently the dominant strain in the United States.
But there’s still a tremendous amount of research to be done that could change how we view Omicron. This research will take time and patience.
What won’t change, though, is that vaccines are the best way to protect yourself and others against COVID-19. (And these recent data provide an even-stronger reason to get a booster now if you are eligible.) Wearing a mask, especially in public indoor settings, offers good protection against the spread of all SARS-CoV-2 variants. If you’ve got symptoms or think you may have been exposed, get tested and stay home if you get a positive result. As we await more answers, it’s as important as ever to use all the tools available to keep yourself, your loved ones, and your community happy and healthy this holiday season.
 SARS-CoV-2 Omicron has extensive but incomplete escape of Pfizer BNT162b2 elicited neutralization and requires ACE2 for infection. Sandile C, et al. Sandile C, et al. medRxiv preprint. December 9, 2021.
 Pfizer and BioNTech provide update on Omicron variant. Pfizer. December 8, 2021.
 Effectiveness of COVID-19 vaccines against the Omicron (B.1.1.529) variant of concern. Andrews N, et al. KHub.net preprint. December 10, 2021.
COVID-19 Research (NIH)
Sigal Lab (Africa Health Research Institute, Durban, South Africa)