SARS-CoV2 vaccines: three cheers and a groan
The scientists and the drug companies did their job, now each of us has to do ours
Less than a year since ‘We’ identified and sequenced the SARS-CoV2 virus and genome and we have vaccines! In fact, we have 3 that might be dosed and injected in the US by New Year’s day. Pfizer (a.k.a. BNT162b2), Moderna (a.k.a. mRNA-1273), and AstraZeneca (a.k.a AZD1222). recently announced preliminary results from phase 3 trials (read: they each vaccinated thousands of people and then followed them to see how many were infected), and the results are, well, pretty great.
So, let’s break it down a bit.
Pfizer, Moderna, and AZ all announced results via press release, not the peer-reviewed medical journal route we'd love to see if we had time for the academic publication process to play out.
They all appear to be a 2-shot package (get a shot today, get a shot a month from now)
They all work!
Pfizer
"Primary efficacy analysis demonstrates BNT162b2 to be 95% effective against COVID-19 beginning 28 days after the first dose;170 confirmed cases of COVID-19 were evaluated, with 162 observed in the placebo group versus 8 in the vaccine group"
95% efficacy is awesome! But keep in mind that this prelim analysis only covers the first month after vaccination. It's unclear how efficacious the vaccine is after that point.
Almost no one had any serious side effects! As someone who hears way to often that "I don't want the flu shot because I feel just as bad after getting the shot as I would if I got the flu", this is huge
Yes, you need a -70F freezer. But, whatever. I'm pretty sure between Pfizer, CVS, and the federal government, they'll figure it out.
Moderna
"The candidate [vaccine] was safe and well-tolerated and noted a vaccine efficacy rate of 94.5%. The findings are statistically significant, meaning they are likely not due to chance. 90 of the cases occurred in the placebo group and 5 occurred in the vaccinated group. There were 11 cases of severe COVID-19 out of the 95 total, all of which occurred in the placebo group."
94.5% efficacy!!! Unlike Pfizer, Moderna / NIH don't report how long these patients were followed, so it's unclear how long this efficacy is good for
Interestingly, Moderna didn't release side effect data. But, based on their phase 1/2 trials (Anderson et al, NEJM, 2020), a lot of people aren't going to feel great after 1 or both shots.
AstraZeneca
"The vaccine was highly effective in preventing COVID-19, the primary endpoint, and no hospitalisations or severe cases of the disease were reported in participants receiving the vaccine. There were a total of 131 COVID-19 cases in the interim analysis. One dosing regimen showed vaccine efficacy of 90% when AZD1222 was given as a half dose, followed by a full dose at least one month apart, and another dosing regimen showed 62% efficacy when given as two full doses at least one month apart"
I'm not sure why 1/2 dose now + full dose later appears to be better than full dose now + full dose now, but that's what they're saying
And, like Moderna, they're not reporting on side effects. But, like Moderna, the phase1/2 trials showed that 60-80% of people experienced "moderate or severe" symptoms. (Folegatti et al, Lancet, 2020.)
So what?
Of the 3, I'd want to take the Pfizer or Moderna vaccine - and of those 2, probably the Pfizer one (less frequent and less severe(?) side effects)
Just because we're going to have vaccines soon, doesn't mean the pandemic will be over any time soon. Please remember:
Not everyone will be vaccinated at the same time
Not everyone will respond to the vaccine in the same way
Not everyone wants the vaccine! And I don't see the US of A mandating vaccines in our lifetime.
Each of these vaccines requires at least 2 shots, and there's no reason to believe we won't need shots in the future to maintain immunity.
Ultimately, achieving herd immunity isn’t just about how good the vaccine works; it’s also about how good we are at accepting and taking the damn injections! Think about it: even if any vaccine were 100% effective, how would that play out if only 50% of, say, the USA, received vaccinations? At best, only 50% of would be immune* to SARS-CoV2.
Vaccine Efficacy X Real world Vaccine Uptake = Real World Vaccine Efficacy
As one of my old med school professors told us: “the best drug is the one the patient is actually going to take”.
Hot Take
I'm hopeful that we'll get to herd immunity (whatever the cutoff for that might be - 60%? 80%?) by next Thanksgiving. But I'm worried that people are going to assume that just because they got vaccinated, they can expect their lives to go "back to normal" (i.e. 2019). Because we'll get the vaccine at different times, and we'll respond differently, we can still expect COVID19 cases throughout 2021...That's also assuming we all get the vaccine. I'm genuinely worried about a significant number of people straight up saying 'no thanks' to a vaccine. Hopefully a good doctor, spouse, partner, or marketing campaign can convince them otherwise…but, I’m skeptical.
Oh, and one last thing, this virus is mutating. Not like crazy fast, but it's still changing. So we'll probably end up with annual or semi-annual doctor visits to get more shots.
*It’s still unclear what immunity in this context really means - are antibodies sufficient? Are “T-cells” the key? It’s probably a combination of both. This is a topic deserving of its own post.