Question for vaccine trial participants

[TheWhalrus]

Hi all,

I have a specific questions for those on vaccine trials. I'd like you to post which vaccine (or placebo) you are receiving and whether you are tested regularly for COVID as part of the trial (or not). I want to know because this makes an important difference to how the various vaccine efficacies are interpreted.

Thanks in advance for your contributions.

This is all available online, have they not all published their protocols?

Pfizer

pfe-pfizercom-d8-prod.s3.amazonaws.com/2020-11/C4591001_Clinical_Protocol_Nov2020.pdf

Moderna
www.modernatx.com/sites/default/files/mRNA-1273-P301-Protocol.pdf

I know someone in the Oxford trial and they get tested frequently for covid, possibly fortnightly.

I’m in the Oxford trial and have a weekly test (for 6 months so far).

Thanks all for your helpful contributions.

@How2Help: yes, i'm aware of published trial protocols, but wanted a 'real-world' answer as some of the protocols are a bit ambiguous, and there might be problems with access to testing in certain places, so it might be that trials are having to deviate from the protocol a bit.

The reason i'm interested is that regular testing could really make a difference to how the efficacy of the Az/Oxford vaccine is interpreted. I would argue that 90% efficacy with regular testing of all participants might actually be better than 95% efficacy without regular testing. Even 62% might be a lot better than it looks, and it means the trials provide some indication of the ability of a vaccine to reduce asymptomatic spread (or not).

Fair enough but the primary endpoint of the Oxford study is: A binary response, whereby a participant is defined as a COVID-19 case if their first case of SARS-CoV-2 RT-PCR-positive symptomatic illness occurs ≥ 15 days post second dose of study intervention. Otherwise, a participant is not defined as a COVID-19 case.

So the published % is on symptomatic cases only, regardless of what testing they did. You will need to ensure you have the % figure for symptomatic and asymptomatic cases to delve further. When I looked last week this figure was not available (it may be now).

My understanding, which may be wrong, is that the numbers were not high enough to draw statistical conclusions yet around asymptomatic spread.

@How2Help: thanks for this point. Although, I suppose the incorporation of regular testing potentially decreases the efficacy in individuals with overlapping symptoms that aren't COVID plus a false-positive test, although that would be quite a niche scenario. Not sure the press release specifies symptomatic cases or otherwise (or what the criteria for being symptomatic actually are). We'll need to wait for the paper to be published for that.

I agree that numbers are currently not high enough to draw conclusions on asymptomatic spread, although knowing the trial is potentially set up to capture that information eventually is valuable to me.

I think the point about false positives in patients with covid-type symptoms is moot, because presumably the chances of that are equal on both the active and placebo arm.

The press release figures are I believe based on the primary outcome above, so is symptomatic cases. The criteria for symptomatic is listed in the protocol (section 8.1.1) and is based on CDC criteria.