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What if it had gone the other way, and longer intervals made the vaccine significantly less effective? I do agree with you on the whole, but for me it’s a very

What if it had gone the other way, and longer intervals made the vaccine significantly less effective? I do agree with you on the whole, but for me it’s a very difficult choice, not an obvious one.

derbOac 5y ago
A few months ago I remember there were interviews and articles with immunologists and virologists. There seemed to be a consistent sentiment with many of them at least that the Pfizer and Moderna protocol intervals were kind of suboptimal from an immunology perspective. The conclusion was that many in the field saw it as obvious that the two companies were trying to maximize the probability of vaccine efficacy in as short of period of time as possible (I don't think they saw the companies as acting immorally, just that they saw it as not making sense unless you understood the time constraints). Many of the people interviewed commented that with unlimited time and lack of public health constraints, they would have expected smaller doses given longer apart. I guess my point is, I'm not an expert in this area but there was a lot of chatter earlier that this was kind of predictable or something.
smnrchrds 5y ago
That would be unexpected. Not impossible, but improbable. Think about it this way: do you know of any other vaccines with 4-week intervals? If all other vaccines use longer intervals, what are the chances that this particular vaccines needs a shorter interval? The decisions made in UK and Canada to delay the second dose were not a random choice. They were expected to work based on the body of knowledge we have from other vaccines and what we know about the immune system. It was by no means a certainty, but a strong probability. And it paid off.
- areyousure 5y ago
  Bexsero (MenB) is two doses given 4 weeks apart. For children receiving their first vaccines for the flu (whether inactivated or live), it is recommended they receive two doses 4 weeks apart. Lots of the early childhood vaccines have minimum spacings of 4 weeks, but are given at 2, 4, and 6 months simply because of standard pediatric followup visit schedules: DTaP, Hib, IPV, PCV13, and Rotavirus. HepB has a first dose at birth and the second at 4 weeks -- 2 months. HPV is available in a 3-dose series with 4 weeks between the first two doses.
  - smnrchrds 5y ago
    Even Bexsero vaccine has recommended interval of at least 1 months or 2 months, not exactly one month or at most 1 month. It seems to be consistent with longer intervals being ok. https://bexsero.ca/content/dam/cf-pharma/bexsero/en_CA/document/bexsero_dosing_schedule_en.pdf https://bexsero.ca/content/dam/cf-pharma/bexsero/en_CA/docum...
indigomm 5y ago
It wouldn't have mattered. The human trials had already shown that just one dose of Pfizer has an efficacy of 89% after 15 days. With a fast-spreading pandemic, the priority is to get as many people on their first dose as possible. This both starts to reduce the rate of infection, and also reduces the death rate. The long-term effectiveness isn't a priority at first for the most developed countries. If necessary they can just order more vaccine after a few months and run a booster campaign later in the year. Cost isn't an issue.

What if it had gone the other way, and longer intervals made the vaccine significantly less effective? I do agree with you on the whole, but for me it’s a very difficult choice, not an obvious one.

derbOac 5y ago

A few months ago I remember there were interviews and articles with immunologists and virologists. There seemed to be a consistent sentiment with many of them at least that the Pfizer and Moderna protocol intervals were kind of suboptimal from an immunology perspective. The conclusion was that many in the field saw it as obvious that the two companies were trying to maximize the probability of vaccine efficacy in as short of period of time as possible (I don't think they saw the companies as acting immorally, just that they saw it as not making sense unless you understood the time constraints). Many of the people interviewed commented that with unlimited time and lack of public health constraints, they would have expected smaller doses given longer apart. I guess my point is, I'm not an expert in this area but there was a lot of chatter earlier that this was kind of predictable or something.

smnrchrds 5y ago

That would be unexpected. Not impossible, but improbable. Think about it this way: do you know of any other vaccines with 4-week intervals? If all other vaccines use longer intervals, what are the chances that this particular vaccines needs a shorter interval? The decisions made in UK and Canada to delay the second dose were not a random choice. They were expected to work based on the body of knowledge we have from other vaccines and what we know about the immune system. It was by no means a certainty, but a strong probability. And it paid off.

areyousure 5y ago
Bexsero (MenB) is two doses given 4 weeks apart. For children receiving their first vaccines for the flu (whether inactivated or live), it is recommended they receive two doses 4 weeks apart. Lots of the early childhood vaccines have minimum spacings of 4 weeks, but are given at 2, 4, and 6 months simply because of standard pediatric followup visit schedules: DTaP, Hib, IPV, PCV13, and Rotavirus. HepB has a first dose at birth and the second at 4 weeks -- 2 months. HPV is available in a 3-dose series with 4 weeks between the first two doses.
- smnrchrds 5y ago
  Even Bexsero vaccine has recommended interval of at least 1 months or 2 months, not exactly one month or at most 1 month. It seems to be consistent with longer intervals being ok. https://bexsero.ca/content/dam/cf-pharma/bexsero/en_CA/document/bexsero_dosing_schedule_en.pdf https://bexsero.ca/content/dam/cf-pharma/bexsero/en_CA/docum...

indigomm 5y ago

It wouldn't have mattered. The human trials had already shown that just one dose of Pfizer has an efficacy of 89% after 15 days. With a fast-spreading pandemic, the priority is to get as many people on their first dose as possible. This both starts to reduce the rate of infection, and also reduces the death rate. The long-term effectiveness isn't a priority at first for the most developed countries. If necessary they can just order more vaccine after a few months and run a booster campaign later in the year. Cost isn't an issue.