I'm not sure I agree with the level of adjustment being a negative here. The point they are making is that have adjusted for confounders ie. considered other covariates (all those listed) and the results still show their exposure (VILP) being associated with their outcome of interest (mortality). It's usually better to account/adjust for as many confounders as possible (happy to be corrected by someone on this!), especially those that are clinically relevant. Usually, more covariates in the model takes it towards the null so if there is still an effect estimate, it's likely to be a better association than using crude values.
My issue with these studies from the UK Biobank though is that the wearable devices are only worn for up to 2 weeks or so, although the follow period is significantly longer in this study. For this study the "participants were required to have at least three valid monitoring days, with at least one of those days being a weekend day". Would be better to have a prospective cohort but good to see associations so further studies can investigate.
PhD student here. Aside from difficulty of accessing articles who don't have institutional access, it's significantly easier to obtain an article from sci-hub. Enter title or DOI - done. To get the same article using uni logins you need to search via database e.g. Medline, then click on the source button. This takes you to different resources you can download from. Once you click through, you can then download the pdf, unless they've decided ePub is the default option in which case you have change this. Rarely, I've had to sign up to attempt to download an article but find once I've done this, my institution doesn't actually have access. The steps are reduced if you're on campus but not much better to be honest. Absolute mess.
For systematic reviews there are one of two ways that I'm aware of: PROSPERO [1] and Cochrane[2]. Cochrane is slightly more rigorous for conducting a review of this type. Although you do declare what meta-analyses you intend to do, you can't be overly explicit as it is largely dependent on the number of studies that are returned in your search strategy. For example two studies is too small for a meta-analysis so you would do a narrative review (discuss what you found).
You’re correct, no evidence at the time JCVI (joint committee for vaccination and immunisation) made the call. However the decision was made on best interests [1] from a public health perspective. Delaying to 12 weeks allowed absolute numbers of people to be immunised once and build up some immunity versus absolute numbers of people vaccinated twice and having higher number of vulnerable populations without any immunity. Of course, this wasn’t taking into the people who had had COVID-19 and had a level of immunity to the virus from exposure.
My issue with these studies from the UK Biobank though is that the wearable devices are only worn for up to 2 weeks or so, although the follow period is significantly longer in this study. For this study the "participants were required to have at least three valid monitoring days, with at least one of those days being a weekend day". Would be better to have a prospective cohort but good to see associations so further studies can investigate.