. >> reporter: proffer joshua selman and his colleagues at stanford krumplgd the numbers for shipping covid vaccine. that takes into account that both the pfizer and moderna vaccines require two doses taken apart. that's to assure that enough second doses are readily available after a three week heard in case of supply disruption. >> i think the current scheme is really putting a premium on avoiding that worst case scenario of a vaccine supply, but the cost of that is that we're not making available as many vaccinations as possible. >> he believes spotting the current surge in deaths could call for front loading the number of vaccine doses being released up steld. an alternative flexible model calls for dropping the amount down to just 10% and releasing the rest now while the virus is spiking, then making up the difference in later cycles. they believe it could prevent between 23 to 29% more new covid cases in the near term. >> this is a dangerous and critical time. we're looking at this two-month period and asking how can we maximize the potential benefit of the doses we have. >> the