WIM no. 17 Spring 2020

מכון ויצמן למדע Prof. Ruth Arnon: Lessons from influenza What the quest for a universal flu vaccine can teach us W ith infections, as with football, a best offense is often a good defense. But while that strategy works for many infectious diseases, it doesn’t work with influenza; thanks to its readiness to mutate, the influenza virus effectively “shifts the goalposts” each year, requiring a new vaccination. Renowned Weizmann Institute immunologist Prof. Ruth Arnon is spearheading a new defense—a universal influenza vaccine that is currently in Phase III of the clinical trial process—that focuses on the parts of the flu virus that stay the same from year to year, gluing the goalposts to the ground once and for all. Prof. Arnon, who emphasized that she is not an expert on coronavirus, says she thinks a similar strategy might also be useful for countering coronaviruses, including the current SARS- CoV2 strain (which causes the COVID-19 disease). That is, a possible pharmaceutical approach to creating a vaccine against COVID-19 involves targeting a particular viral protein, called SPIKE, which is an important offensive player in the virus’s infection game. Another approach would be targeting a protein, or segments of the virus proteins, that are common across the most virulent types of coronavirus, including SARS-CoV-2, and MERS-CoV. “If I were working in the coronavirus field,” says Prof. Arnon, “this non-changing protein approach is where I would focus my efforts.” It’s going to take time and patience. Even if a universal coronavirus vaccine were identified today, it is unlikely to be of use this year. Time and patience Part of the challenge is one that is common to all vaccine production processes. Vaccines must be tested in animals, but there are no good animal models of how the COVID-19 infection cycle works in humans, which means preclinical trials will likely have to be carried out. Moreover, a vaccine must be tested in people for safety—a process that can take weeks to months. And then, once a vaccine is identified, it must be produced in sufficient mass quantities—and administered far and wide—in order for herd immunity to take effect. Herd immunity is a form of indirect protection that occurs when a large percentage of a population has become immune to an infection, thereby providing a measure of protection to individuals who are not vaccinated. In effect, the virus runs out of hosts. Furthermore, vaccine trials tend to take longer than trials for, say, cancer drugs; the vaccines are administered to healthy people, and efficacy can only be determined through a painstaking “wait and see” approach, to find out whether the vaccines indeed fend off infection. g Prof. Arnon is the past president of the Israel Academy of Sciences and Humanities, and co- developer of the blockbuster multiple sclerosis drug Copaxone. Her universal flu vaccine is in Phase III clinical trials. Weizmann MAGAZINE Coronavirus Response