New Spear Bio Ultrasensitive Immunoassay Neutralizing Antibodies Test Kits for Covid Variants

– NAB-Sure™ Test Kits now available for XBB.1.5 & BQ.1.1-

Woburn, MA, July 10, 2023Ultrasensitive immunoassays developer Spear Bio is expanding its family of NAB-Sure SARS Cov-2 Neutralizing Antibodies test kits. Previously released kits included the original Wild Type strain and Omicron BA.4/5 variants. It has now added test kits for Omicron variants XBB.1.5 and BQ.1.1.

Effective vaccines have been critical to managing the COVID-19 pandemic. However, vaccines need to be continually re-evaluated and adapted to new strains. This requires consistent, easily deployed measurement methods of immune responses to variants and vaccines, such as Spear Bio’s new XBB.1.5 and BQ.1.1 variants test kits.

The U.S. Food and Drug Administration (FDA) recently recommended XBB.1.5-specific vaccines for this fall. “Based on the totality of the evidence, FDA has advised manufacturers who will be updating their COVID-19 vaccines that they should develop vaccines with a monovalent XBB.1.5 composition,” the agency said.

Last year, Spear Bio introduced its NAB-Sure SARS-CoV-2 Neutralizing Antibody Test Kit, an ultrasensitive cell-free assay which uses real-time PCR systems to quantify neutralizing antibodies (NAbs) from plasma, serum, or dried blood spot (DBS) samples. The assay can be used to monitor immune responses in populations of interest, post-vaccination or post-infection, and show neutralizing antibody durability in longitudinal studies.

“Whether for public health surveillance, clinical research, or vaccine development, neutralizing antibodies are key to understanding immune responses to vaccines and infections,” said Jerome Clavel, CEO of Spear Bio. “We are glad to be able to provide updated variants, such as XBB.1.5 and BQ1.1, especially in light of the recent FDA recommendation for XBB.1.5 vaccines.”

NAB-Sure – research use only – offers researchers a highly sensitive, accurate and precise cell-free alternative to neutralizing antibody testing: 

  • Wild-type and Omicron BA.1, BA.4/5, XBB.1.5 & BQ.1.1 variants
  • PRNT level accuracy with qPCR
  • High lab-to-lab consistency (4.8% inter-lab CV)
  • Easy-to-use workflow
  • High throughput with automation compatibility 
  • 6 hours of test time
  • Qualitative and quantitative NAb measurements 

To learn more about NAB-Sure SARS-CoV-2 Assay contact us at [email protected] or visit

 About Spear Bio 

Spear Bio (, founded in 2021 by scientists from the Wyss Institute for Biologically Inspired Engineering at Harvard University, is headquartered in Woburn, MA. The company is focused on providing scalable solutions for ultrasensitive protein biomarker measurements from small sample volumes. We collaborate closely with industry and academic researchers, as well as public health officials. Our aim is to develop more ultrasensitive detection approaches in support of clinical research, non-invasive microsample collection methods, and cutting-edge laboratory diagnostics.