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Big news today about another vaccine candidate. Take home messages:
-It's safe
-It's immunogenic (neutralizing antibodies and antigen-specific T cells)
-It's a good size (n=1077 patients, 543 of whom got the vaccine vs 534 controls)
However, we don't know if it's effective. https://twitter.com/TheLancet/status/1285207186591887360
-It's safe
-It's immunogenic (neutralizing antibodies and antigen-specific T cells)
-It's a good size (n=1077 patients, 543 of whom got the vaccine vs 534 controls)
However, we don't know if it's effective. https://twitter.com/TheLancet/status/1285207186591887360
I said similar things about the Moderna phase I trial results last week to @nytDeniseGrady @nytimes. The results are promising, but preliminary. Measuring immune responses to the vaccine is not the same thing as demonstrating vaccine efficacy. https://www.nytimes.com/2020/07/14/health/cornavirus-vaccine-moderna.html
For the Oxford vaccine, there is preclinical data showing efficacy at protecting against disease in rhesus macaques (monkeys), in this excellent study by @DrNeeltje and colleagues. That is very encouraging. https://www.biorxiv.org/content/10.1101/2020.05.13.093195v1
They have also shown that this vaccine platform protects rhesus macaques against MERS-CoV, suggesting that the platform itself works for immunizing subjects against other betacoronaviruses. https://advances.sciencemag.org/content/6/24/eaba8399
It's important to note that while this did not provide sterilizing immunity against #SARSCoV2 (the monkeys can still get infected), it protected them against severe disease. That would still be a substantial public health benefit.
Normally it takes years to conduct a phase 3 trial that looks at efficacy. This is because you have to recruit and vaccinate thousands of subjects, then wait for enough of them to get exposed in the course of their daily lives to show they are protected.
Obviously, because of the pandemic, this will be shortened. I suspect any vaccine showing a shred of efficacy in phase 3 trials will be fast-tracked and approved. This will take a few months. I fear that people have unrealistic expectations of this time frame.
While the phase 3 candidates are being manufactured in advance, there still won't be enough vaccine to give it to everyone as soon as they achieve approval. Plus vaccines take a week or two to induce immune responses. Some vaccines may require a booster (looking at you Moderna).
So I want to emphasize that people should have realistic expectations. To "end the pandemic" and get back to normal, enough people have to get it and it has to work well enough that we can feel confident relaxing measures to prevent community transmission.
Vaccine approval doesn't mean that the pandemic is instantly over and things will revert back to normal overnight. We need to make sure there is widespread access to the vaccine. We need to win hearts and minds of vaccine skeptics.
The bottom line is that I'm cautiously optimistic about the vaccine data that's coming out, from Moderna and Oxford phase I/II human trials as well as monkey studies from Johnson and Johnson/Dan Barouch at Beth Israel and the Fuller lab at UW.
Clearly these vaccines induce immune responses and they appear to meet acceptable safety standards. However, this is still a marathon, and we're only halfway to the finish line. We need to manage expectations that we still will not have any vaccine until very late in 2020.
In the meantime, we must remain vigilant about the sacrifices that are needed to stop the spread, particularly in communities with surging case numbers. There is a long way to go before this is over and we must brace ourselves for the long haul.
