It's very important. We don't have full information about a natural immunity after a natural infection with SARS-CoV-2. That's a very important priority for the immunity task force. Canada's immunity task force is undertaking seroepidemiology studies on patients, just on the general population, to see how many have become infected without any symptoms and without being diagnosed, as well as to follow patients who've recovered from SARS-CoV-2, to see how long they maintain their antibodies.
Again, we're not 100% sure yet, and research is still under way about what is the most important factor in the immune system. We talk about an antibody, but there's also cellular immunity, which in viruses is very important. How long the protection lasts is something we need to know. That's with every vaccine, not just SARS-CoV-2 vaccines, which is why for the measles vaccine, for example, you get one dose as a child and you're protected for life, whereas with the influenza virus, it lasts for, perhaps, one season. We know that for an influenza virus, even by the second half of a season immunity is dropping off. Where SARS-CoV-2 will fit in, time will tell. If it's not of very long duration, that may just mean we will need to have second boosters, which again becomes a question of how many doses we are going to need over time.