first of all, in terms of disease severity, so far, the early reports suggest it's not producing more severe disease in anything we've seen before. delta, the delta variant or the alpha variant. i think the most -- what most -- concerns most people is the fact that there are more than 30 mutations in the spike protein, which is pretty high, including those in the receptor binding domain. that interacts with the receptor so there's worry that this could thwart some of the protection afforded by the immune response to vaccines. but we'll know that over the next week or two. so in our lab, we're looking at how our vaccine holds up against the variant, as is moderna and pfizer, and so we'll know that over the next week or so. but a key point there is, remember, we've had vaccine resistant variants before. we had the beta variant out of south africa. you remember the b.1.351 and we had the lambda variant. those were not necessarily big spreaders so they never really