Hurrah for Disease Burden?
We touched on this earlier in the year, but worth repeating in the wake of the Pfizer/BioNTech/Moderna/AstraZeneca successes in their phase 3 trials. The US was always going to have phase 3 vaccine data before other countries, such as China, simply because we have a far greater disease burden. Here are some rough numbers to demonstrate:
US has 320M residents. During the two months of the Pfizer trial we had about 55k cases per day meaning the chance an American was diagnosed with Covid in the two months the trial ran was ~1%. The trial required a certain number of people to develop symptomatic Covid. So if half of the infected had symptoms, that would mean there was about a 0.5% chance a person in America would be symptomatic and diagnosed with Covid in that two-month trial window.
Pfizer enrolled 43k people, ~22k who received the placebo. So we would expect about 0.5% of the placebo group to get symptomatic Covid, which is ~110 people. In reality, the trial ended up having 132 events in the placebo arm plus 8 in the vaccine arm for a total of 140 events.
Now to China. They're reporting something almost unbelievably low for a country of 1.4B people - 25 cases per day. So over two months what are the odds an average Chinese resident comes down with Covid? 0.00011%. (Which is amazing if you live in China, by the way. )
Let's go ahead and assume all those diagnosed in China are symptomatic. How many people would they have to enroll in the placebo arm of a vaccine trial to get 132 events in two months? 123 MILLION people. And that's just the placebo arm! What if they extended the trial to 12 months? Still 20 million placebo patients. Even China would have a hard time doing something like that.
So without any disease burden to speak of, it's difficult for China to conclude if their vaccine/s work. This is just one of the reasons why companies in the US/Europe have been able to bring these vaccines to consumers with record speed - if you have millions of disease cases, it's far easier to determine if a vaccine works.
I Declare Immunityyyy!!!
Patients seem to show substantial covid immune memory even six months after initial infection. Not true for everyone, but if true for the majority this is a really big deal. Until now, everyone wanted to assume lasting immunity was real, but we really didn't know. Looks like we can now be confident in longer-lasting immunity. This is yet another indicator that we may see normalcy in spring/summer 2021.
Monkey Troubles
Eli Lilly ran into a delay developing its Covid-19 antibody - a monkey shortage. China is the predominant supplier of bred macaques and had banned exports in the wake of the pandemic. Lot of international animal shipments have seen the same thing happen - our local zoo in Lafayette, IN is still waiting on their African penguins to arrive.
In comparison, BioPharmGuy's friend was able to procure some poison dart frogs and a gecko with ease. So domestic animal shipments appear to have continued unabated. Did you know captive-bred poison dart frogs are harmless?
