Hi, John. I'd love to see some expert like, say, a virologist discuss immunity to the viral shell "carriers" of certain vaccines, e. g. the AZ and J&J vaccines for COVID-19. My particular train of thought: they use a viral capsid to carry genetic material into the host cell, which then manufactures viral proteins to sensitize the immune system. They also will generally contain an adjuvant, yes?
So ... the host presumably develops immunity to both the carrier virus and the intended target, and I can't see how the adjuvant can only intensify immunity to the target. Now the patient is immune to the carrier. By itself, immunity to a harmless adenovirus (or whatever type) is fine, but what if you need a booster shot? Wouldn't there be a reasonable chance that the immune system would destroy the pseudo-virions containing the viral genetic material before it entered the patient's cells? OTOH, I don't know a darn thing about the kinetics of the immune system ... if you wait a year for circulating antibodies to drop, would the immune system react too slowly (with memory cells having to proliferate) to prevent re-immunization?
This is a great question. There are definitely substantial immune reactions to the vectors used in chimeric vector vaccines. I don't think it's typical for such vaccines to contain an adjuvant--this will depend upon whether the vector itself solicits a meaningful inflammatory response. Sometimes the vector induces enough of an infection that it is, sort of, self-adjuvanting.
I've written a little bit about this in an earlier edition of the newsletter, actually in two issues:
When it comes to reactions against the vector, I have to confess that I don't feel fully equipped to answer you. I do know that several chimeric COVID-19 vaccine designs have had major problems with reactions to the vector befouling immunity. I think this may also be the reason that the half-dose priming with the AstraZeneca vaccine worked better; I think this generated less of a response to the vector, allowing the boost to be more effective. But, again, I feel like this goes a little bit out of my depth. However, I do know someone who is qualified and an expert on this. I'm going to check in with her and see if I can do an interview with her for a future issue, where we can try to address some of your questions more specifically. I'm not sure that there are straightforward answers to any of these.
Hi, John. I'd love to see some expert like, say, a virologist discuss immunity to the viral shell "carriers" of certain vaccines, e. g. the AZ and J&J vaccines for COVID-19. My particular train of thought: they use a viral capsid to carry genetic material into the host cell, which then manufactures viral proteins to sensitize the immune system. They also will generally contain an adjuvant, yes?
So ... the host presumably develops immunity to both the carrier virus and the intended target, and I can't see how the adjuvant can only intensify immunity to the target. Now the patient is immune to the carrier. By itself, immunity to a harmless adenovirus (or whatever type) is fine, but what if you need a booster shot? Wouldn't there be a reasonable chance that the immune system would destroy the pseudo-virions containing the viral genetic material before it entered the patient's cells? OTOH, I don't know a darn thing about the kinetics of the immune system ... if you wait a year for circulating antibodies to drop, would the immune system react too slowly (with memory cells having to proliferate) to prevent re-immunization?
Thanks.
Hi Carl!
This is a great question. There are definitely substantial immune reactions to the vectors used in chimeric vector vaccines. I don't think it's typical for such vaccines to contain an adjuvant--this will depend upon whether the vector itself solicits a meaningful inflammatory response. Sometimes the vector induces enough of an infection that it is, sort of, self-adjuvanting.
I've written a little bit about this in an earlier edition of the newsletter, actually in two issues:
https://covidtransmissions.substack.com/p/covid-transmissions-for-9-1-2020
https://covidtransmissions.substack.com/p/covid-transmissions-for-9-3-2020
When it comes to reactions against the vector, I have to confess that I don't feel fully equipped to answer you. I do know that several chimeric COVID-19 vaccine designs have had major problems with reactions to the vector befouling immunity. I think this may also be the reason that the half-dose priming with the AstraZeneca vaccine worked better; I think this generated less of a response to the vector, allowing the boost to be more effective. But, again, I feel like this goes a little bit out of my depth. However, I do know someone who is qualified and an expert on this. I'm going to check in with her and see if I can do an interview with her for a future issue, where we can try to address some of your questions more specifically. I'm not sure that there are straightforward answers to any of these.
Hey, good news: preprint indicates that the BioNTech vaccine should protect against both the N501Y variants. Not yet tested against E484K.
https://www.snopes.com/ap/2021/01/08/pfizer-study-suggests-vaccine-works-against-virus-variant/