Pondering the contentious COVID19 vaccine dose 2 "hold or give", optimal timing issue: if continuing to give first doses (when shipment is delayed, clearly) could save more lives, what kind of parameters should be put around dose 2 timing to guide distribution? Useful bits:
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British approach- pragmatic, protect more in the short-term by extending the second dose up to 12 weeks - immunologists feel this 8 week delay would be unlikely to have a negative effect on the overall immune response post-boost. Call for monitoring of immune responses...
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"Modelling data has shown that vaccination has by far the largest chance of reducing the disease burden and death rate compared with other measures. Any risks from actions taken now must be balanced against risks of actions not taken."
https://www.immunology.org/policy-and-public-affairs/briefings-and-position-statements/COVID-19-vaccine-dosing-schedules
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"Concerns over hypothetical consequences of putting the virus under pressure from non-sterilising vaccine regimes have to be balanced against a view of what we would face through the virus spreading at the current rate in our communities." - although again I'd agree MONITOR
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Here, NACI added Appendix C discussing ethical considerations in the hold versus distribute more first doses debate: https://www.canada.ca/en/public-health/services/immunization/national-advisory-committee-on-immunization-naci/recommendations-use-covid-19-vaccines.html?utm_source=link.cep.health&utm_medium=urlshortener&utm_campaign=covid-vaccine#a7, looks at important issues through what I'd call a more tentative lens in terms of reasonable inferences about protection from dose 1
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It comes down to whether the observed >90% protection 2 weeks after dose 1 (pre dose 2) is thought likely to drop substantially after 3-4 weeks, and whether in the absence of direct data reasonable biological inference can be made in a risk-benefit calculation
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NACI "This may provide greater access to a greater number of individuals providing at least some short-term protection, which could increase equity when local disease burden is high. However, health equity principles may be undermined if protection is not adequate...
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So if in all likelihood the good protection from a first dose is sustained at least for even an additional 4-8 weeks (this seems reasonable to assume) giving more first doses if you have no further supply available, rather than holding them (especially for LTC outbreaks) is...
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...I think just a little bit bold, a very large bit pragmatic, and overall justifiable to me.
Keys: open communication, transparency, commit to second doses with stated time frame, study and share results. (Note vaccine gives ~4X higher antibody than infection).
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