Researchers has developed a rapid blood test that could confirm a person has been vaccinated


One challenge as society reopens is identifying who has been vaccinated for SARS-CoV-2, the virus that causes COVID-19.

A team of Johns Hopkins researchers has developed a rapid blood test that could confirm a person has been vaccinated while they wait to board a plane or enter a sporting event.

Their COVID-19 antibody test is similar to one used at home to determine blood type, where the user pricks a finger and places a drop of blood on a card. A fusion protein developed by the research team is housed on the card and detects COVID-19 antibodies, tiny proteins in the blood the immune system produces to “remember” viral encounters and provide immunity to future infections.

Results come back in less than five minutes, faster than current lateral flow tests to detect antibodies at point of care, while also potentially providing a clearer result.

Robert Kruse, M.D., Ph.D., who created the blood test, says it could be used to confirm a person’s vaccination instead of having to show a vaccine card.

“If a business is using the honor system for vaccinations, now they could test people on-site,” he says.

Kruse is lead author of a paper posted online earlier this month that reported results of the test on 400 blood samples, half of which were from prior COVID-19 patients.

The test correctly identified antibodies in previously infected patients 87.5% of the time, a slightly higher rate than ELISA tests performed in hospitals that require hours to perform. The paper is being peer-reviewed.

Demonstration of the test. Credit: Robert Kruse

The test uses hemagglutination, in which the degree of clumping together of red blood cells reveals the concentration of antibodies. Kruse, a pathology resident at the Johns Hopkins University School of Medicine, said the hemagglutination results could let people know if they still have protection months after they received the vaccine or if they need a booster shot.

The degree of hemagglutination also correlated with levels of neutralizing antibodies in patients, which protect against viral infection.

Immunocompromised patients, who studies have shown don’t always respond to the COVID-19 vaccine, could test their antibody level and see if the vaccine is working for them, says Yuting Huang, M.D., Ph.D., Kruse’s co-author and a research fellow at Johns Hopkins as well as chief resident of internal medicine at the University of Maryland Medical Center Midtown Campus.

Kruse and Huang developed the test in the lab of Zack Z. Wang, Ph.D., an associate professor at Johns Hopkins in the Division of Hematology. Kruse says the research is an example of the “Hopkins network coming through”: Colleagues in pathology connected Kruse and Huang with researchers from the Johns Hopkins Bloomberg School of Public Health who already had patient samples and test results they were using for their own COVID-19 studies, allowing for collaboration and data-sharing.

“If those collaborating labs didn’t have those samples, we wouldn’t really have known how well it worked,” says Kruse.

Johns Hopkins Technology Ventures is seeking patent protection for the technology, which is available for licensing. The test’s creators are seeking an industry collaborator to manufacture the cards and have applied for funding through TEDCO’s Maryland Innovation Initiative to assist in commercializing its research.

The COVID-19 pandemic has impacted nearly all facets of health and society. The scale and speed with which SARS-CoV-2 infection spread, introduced a myriad of challenges. Early on, testing was identified as being critical to contend with the global health crisis.

Testing is needed both for the diagnosis of those who are actively infected, but also for monitoring of those who have recovered. The latter is increasingly important for immune surveillance, which in turn has a range of applications spanning ascertainment of vaccination uptake to travel. This has led to a surge in the development and marketing of SARS-CoV-2 serology assays to monitor antibody development.

Antibodies confer protection in the overwhelming majority (>90%) of seropositive individuals, with the caveat that the longevity of those antibodies has yet to be determined.1 Further, many of the approved SARS-CoV-2 vaccines in use confer high levels of protection against SARS-CoV-2 by provoking a brisk humoral response.2

The presence of antibodies has also been the basis for selected therapeutics such as COVID-19 convalescent plasma (CCP)3 and monoclonal antibodies against COVID-19.4

A determination of serostatus is predictive of response to treatment with these therapies. For example, those who are seronegative at diagnosis have been found to have a significant decrease in hospitalization rate following monoclonal antibody therapy; by contrast, seropositive patients do not benefit significantly from monoclonal antibody therapy.4 Similarly, CCP appears to be optimally beneficial when high titer units are provided early in disease course.5,6

Recent studies have shown that individuals who have recovered from COVID-19 may only require a single dose of vaccine to confer comparable protection to naïve individuals following receipt of two vaccine doses.7 Modification of existing vaccine policy accordingly could reduce the total amount of vaccine doses needed to achieve herd immunity. Nonetheless, it would require a rapid method to screen individuals for antibodies (i.e. to confirm prior infection).

To date, the rapid SARS-CoV-2 antibody tests approved under emergency use authorization are lateral flow assays, whose performance characteristics have been highly variable.8 Furthermore, lateral flow tests do not offer any quantitative data on antibody levels; the latter are important given the wide range of antibody responses, particularly following mild SARS-CoV-2 infection.9

We sought to develop a point-of-care test for SARS-CoV-2 antibody detection based on hemagglutination, leveraging a test platform that is already routinely used at the point-of-care for determination of blood types. Previous work that demonstrated proof of concept for hemagglutination-based SARS-CoV-2 antibody detection, but requiring a one-hour incubation time and pipetting in a 96-well plate.10,11 We also sought to determine if the test could yield a semi-quantitative readout of antibody levels among COVID-19 recovered patients within few minutes, which would represent the first rapid SARS-CoV-2 serology test to do so.

reference link :

More information: Robert L. Kruse et al, A hemagglutination-based, semi-quantitative test for point-of-care determination of SARS-CoV-2 antibody levels, medRxiv (2021). DOI: 10.1101/2021.05.01.21256452


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