A series of serum biomarkers, identified in rhesus macaques, can differentiate a primary infection and reinfection. Now a tool that uses these biomarkers can help identify surges in reinfection.
Many experts now predict that Covid-19, which has so far killed more than 5.5 million people worldwide, will remain endemic as new infectious variants of SARS-CoV-2 emerge. These new variants could present a higher risk of reinfection (infecting people who have already had Covid-19) than the previous ones. Rapid identification of cases and spikes in reinfection could improve public health responses and reveal variants that escape the protection offered by vaccination.
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Harvard Medicine and the company SpaceX, suggests a way to keep track of those cases. In the work, a multi-institutional group of researchers identified immunological blood biomarkers that correspond to reinfection and re-exposure to the virus.
“In the context of declining natural immunity and vaccines, reinfections have emerged worldwide, including among previously infected and vaccinated people,” noted immunologists, virologists, biologists and others who worked on the study.
Previous studies have reported that rhesus macaques have a clinical response to SARS-CoV-2 infection. similar to that of humans. For the new study, the researchers studied a group of rhesus macaques that had previously been infected with the virus. They exposed the primates to a different variant of the virus, in varying doses, and collected blood samples before and after the original infection and the new challenge.
In particular, analysis of blood samples revealed different biomarkers of reinfection. These included elevated levels of immunoglobulin antibodies that bind to the Spike protein, the nucleocapsid protein or other parts of the virus particle. Animals exposed to higher doses of the virus showed higher SARS-CoV-2 immunoglobulin responses.
The authors reported that these immunological features differentiated primary infection from rechallenge and reinfection in macaques. The researchers then analyzed blood samples from a small group of humans participating in a cohort of community policing at SpaceX and had been reinfected with the coronavirus. The human study confirmed the findings of the macaque study.
The researchers note that simple, inexpensive and widely accessible surveillance tools are needed to identify new sources of infection, the authors noted. The new work, they added, shows how simple titles could be used as readily available markers of reinfection. “Our ability to monitor and control both infection and re-infection depends on the development of simple and immunological detection strategies.