AstraZeneca Vaccine 70% Effective

apnews.com

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I was talking with a doctor friend today, who indicated that a 70% effective vaccine will be basically useless in the face of a more contagious strain. She said even if 100% of people get the vaccine (not likely), the 30% of people for whom it is not effective would allow it to spread to a greater extent than we would want.

In the peer reviewed study for the vaccine, it showed that it prevented hospitalisations [1]. Surely that’s still valuable?

Also a separate study seemed to show anywhere between 60% to 80% efficacy is needed depending on vaccine coverage - 70% requires 75% coverage [2].

> Simulation experiments revealed that to prevent an epidemic (reduce the peak by >99%), the vaccine efficacy has to be at least 60% when vaccination coverage is 100% (reproduction number=2.5–3.5). This vaccine efficacy threshold rises to 70% when coverage drops to 75% and up to 80% when coverage drops to 60% when reproduction number is 2.5, rising to 80% when coverage drops to 75% when the reproduction number is 3.5.

Also, does anyone know - supposedly the Oxford vaccine had swab tests for the virus every week to catch cases even if trial participants weren’t showing symptoms, whereas for the Pfizer/BioNTech vaccine they were only swabbing if someone showed symptoms. Would that not have a large effect on efficacy numbers?

[1] https://www.thelancet.com/journals/lancet/article/PIIS0140-6...

[2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7361120/

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