I'm not really getting it. If the vaccines are not generating a good enough response in some people, why are we not putting them solely on monthly antibodies shots?
In general, you wouldn't want to use a drug in a way that it hasn't been tested (monthly rather than one-time), especially when treating people who are particularly vulnerable. This AstraZeneca announcement a couple weeks ago seems to be the first clinical trial to test monthly shots and show that this could work. It was a smaller trial than Pfizer's vaccine - 5000 people - but they say they think it could be available by the end of the year. It would need to get approved and manufactured. T T T
Or if something in the third shot is boosting the response to adequate levels, why aren't we giving that shot earlier or increasing the dosage of the first 2 shots?
It has to do with the way the immune system responds to the vaccine. This is beyond my intro bio course, so I don't know how it works, or if it's even known, but what I saw recently was something about the maturation of the immune response over time. So it's not that you need a higher dose in the beginning, but that you need to give the body time to ramp up after the first dose, and then it becomes able to respond more effectively to the second. Actually there was one report that people did just as well when just half a dose was used for the first shot, then a regular dose for the second. I think that was Moderna.
Remember early on, when Pfizer/Moderna said doses should be 3-4 weeks apart, and England (and maybe Canada) wanted to give everyone one dose first, so they separated the doses by 8 or 12 weeks instead of 3-4. When they later looked at antibody levels in those people, they found that 8 weeks was the sweet spot - More antibodies were eventually produced in that group than in those whose doses were separated by 4 or 12 weeks.
I just found this CDC page on immunocompromised people and it's suggesting a third dose 4 wks after the 2nd.
"CDC recommends that people with moderately to severely compromised immune systems receive an additional dose of mRNA COVID-19 vaccine at least 28 days after a second dose of Pfizer-BioNTech COVID-19 vaccine or Moderna COVID-19 vaccine."
https://www.cdc.gov/coronavirus/2019-ncov/vaccines/recommendations/immuno.htmlAnd why is all of this guidance regarding prophylaxis specifically for a known exposure?
It could be it's just a matter of supply. Monoclonals were first reserved to treat the infected elderly, obese, and those who seemed particularly vulnerable. It seems it's more widely available now, but perhaps they want to maintain the supply for those with the highest medical need.
Isn't a big part of Covid's problem that most exposure is presymptomatic, and therefore harder to prevent? It seems like we're missing the opportunity to prevent a significant number of hospitalizations and severe cases.
That's why we have the vaccine.
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