Dear Ministry of Health,

1) On the 8th of July 2022 there was a change on the table 'Vaccination details' on the Covid-19 Case demographics page (https://www.health.govt.nz/covid-19-nove...) . Compared to same table on the 7th July, total cases of Covid-19 reduced for Partially vaccinated by 11,421, and Fully vaccinated reduced 853. Unvaccinated and boostered on the other hand increased by 14336, and 45,636 cases respectively.
Can you please explain the case definition or allocation policy that resulted in these significant changes?
2) On the same table on the same day, hospitalisations decreased for all categories (except for the new 'Under 12 years old' category). Presumably this is because non-covid related hospitalisations have been removed as per the note at the bottom of the table. But the decrease was not any where near uniform. Unvaccinated decreased only 11.6% while partially vaccinated,fully vaccinated, and boostered decreased 71.9%, 56%, and 44.1% respectively.
Why would the new policy result in a disproportionate reduction especially for the unvaccinated category?
3) What is the reason for changing the 'Not eligible' category to 'Under 12 years old'? Does the latter include both vaccinated and unvaccinated? If so, what are the numbers for each?
4) Does the ministry record the number of all hospitalisations for any reason by vaccination status? If so can you supply the totals for the month of June?
5) on the Vaccination Data page for the table 'Total Vacinations 12+' There is an entry for 'Third Primary'. What is this category for?

Yours faithfully,

P McKenna

Dear Dr Old

Thankyou for your reply.
May I ask for some clarification.

You state: “The vaccination status of cases was classified incorrectly for approximately a week following changes introduced with our reporting upgrades on 6 July 2022. This was due to a coding error that resulted in vaccination status of cases being reported as it was a week after they tested positive for COVID-19, rather than a week before they tested positive for COVID-19. “

1a. From this I gather that the correct method of recording is if someone tests positive, their vaccination status is not taken as it is on the day of positive test, but instead, it is taken as what it was 1 week earlier. So if, for example, an unvaccinated person gets their first dose on the 1st of July and tests positive on the 7th of July, the case will be counted as an unvaccinated case. Is this assessment correct?
1b. I can see how this would result in a jump of 43k cases for the boosted since that is what would be expected given the case rate of boosted people since February (43k is roughly 1 weeks worth of cases). I can also see how 1 dose and 2 dose would drop, since some 2 dose people would be counted as boosted, and some 1 dose as 2dose. But the increase in unvaccinated does not seem to make sense since no one can be vaccinated before a test and then unvaccinated after it. The movement should be UP the vaccination 'food chain' not down it. The quoted paragraph, as it relates to unvaccinated, seems to say that 11,421 cases were erroneously labelled ‘unvaccinated’ because that is what they were one week after positive test, when they should have been labelled ‘vaccinated’ because that was what they were one week before positive test. Obviously one can not become physically unvaccinated so are these people subject to reclassification for some reason, or is there another explanation?

You did not address Question 2 except by referencing the spreadsheet. This sheet appears to provide the hospitalisations and ICU admissions for the days leading up to, and immediately after the change in definition which is nice, but my question refers to the disproportionate reductions seen across the different cohorts. The deleted cases represent those who had a positive test result but went to hospital for a non-covid reason- correct? If you were to reduce these deleted cases as a ratio to the number of covid cases in the respective cohorts, it demonstrates a significant excess hospitalisation among the vaccinated numbering in the thousands- a very high percentage. This gets worse if you consider that the case rates for unvaccinated appear to be very much under reported (they are about half the case rate of 2 dose and boosted).

This is a very small group of hospitalisations - about 1% of all hospitalisations, so it is only a small signal. But it is a very alarming one. If one were to extrapolate, even only a small fraction of this increased rate, to the other 99% of hospitalisations the results would be a large number of excess hospitalisations. And we are in fact seeing hospitals stretched to capacity so the hypothesis I am hinting at is at least plausible.

2a) Has the Ministry identified this?
2b)Is the ministry concerned by this? If not, why not? If so, what is being done, or could be done to further investigate?

4) My reason for Q4 was that if the MoH did record vaccination status it would be easy to check if this effect was taking place across all hospitalisations. It may be that MoH is not collating or reporting on this, but do hospitals collect this data at time of admission?

Thanking you for your time in advance,

Yours sincerely,

P McKenna