Dear Editor, Serena Hunter (in her letter on December 11 – No jab, no job policy) wrote that “Gibraltar, population of 33,000, over 118% vaccinated (beat that), and facing a surge in cases”.

She used this with similar situations in other countries to conclude that “We really need to wake up to what is going on around the world, and realise it (Covid) is not a disease of the unvaccinated.”

Like many of your readers, the idea that Gibraltar vaccinated more than its entire resident population peaked my interest. I found online values from 99% through 118% to 140% or more. The reason was simple: Gibraltar vaccinated thousands of its non-resident workers while most reports included them as though they were residents thereby giving impossible percentages above 100%.

Gibraltar has a resident population of about 34,000 of which 27,000 are adults (15 years or older) and 7000 are children. In mid-January they started vaccinating all adults and this was “completed” around mid-May. Although it has been sometimes claimed that 99% of the population was vaccinated this is probably exaggerated. It is more likely that at best 95% of adult residents were vaccinated considering reports that about 4% refused to be vaccinated. Erring on the conservative side I will assume 90% or 24,500 adult residents were vaccinated leaving 2500 unvaccinated.

Gibraltar has had three waves of Covid with the first before anyone was vaccinated and the other two when most adults were vaxxed.

The pre-vax Covid wave from mid-December 2020 to end-of-February 2021 infected about 3135 adults and 87 died, a death rate of about 2.8% or 28 per 1000. In strong contrast, the two smaller waves post-vax waves, July-August and October-December (18^th), infected about 3414 adults and six died, a death rate of 0.2% or two per 1000.

The conclusion is obvious: vaccination dramatically lowered the chances of adults dying of Covid. Gibraltar also reported that Covid was the actual cause of death in more than 90% of the fatalities.

In its daily data, Gibraltar recorded infected people according to their age group, their vaccination status and their residence status. We will consider only resident adults to assess the main effect of vaccination.

The daily count of infections was very variable and rather than cherry-pick a few days to evaluate the effect of vaccination we’ll take the whole month of November to give a more solid basis for analysis.

During November, vaxxed adults averaged 17 infected each day while unvaxxed adults averaged 31 infected per day. Seventeen out of 24,000 vaxxed adults gives an infection rate of 0.07% or about half-a-person per 1000. Thirty-one out of 2500 unvaxxed adults gives a rate of 1.2% or 12 people per 1000 – a rate 24 times greater than for vaxxed adults!

Although there will be other factors involved in a person’s chance of being infected, for example mask wearing, these are very unlikely to alter the basic conclusion that in Gibraltar unvaccinated adults are far more likely to become Covid-infected and to die of the infection than vaccinated adults. In summary, Covid is primarily a disease of the unvaccinated.

Biological sciences use statistics to deal with the inherent uncertainly of biological processes, such as the rate of infection in a population. As a biologist I have often said “There are lies, damn lies, and statistics”. With this in mind, I welcome any alternative analysis of the Covid situation in Gibraltar.

Gerald McCormack
Biologist

Serena (Hunter) is obviously well read. Unfortunately, she has cherry picked one statistic from the important Lancet paper, which is that infected household contacts have a similar initial viral load, whether vaccinated or unvaccinated (Vaccinated versus unvaccinated, December 20). That’s true.

What she neglects is that the vaccinated cohort were significantly older (a strong independent risk factor), had a much more rapid decline in viral load and, critically, had a much lower Secondary Attack Rate i.e. were much less likely to infect others.

The vaccinated protect not only themselves but also those around them, including the unvaccinated (mostly children), the sick and the elderly. Serena disputes the indisputable.

I don’t expect to change her mind but seek more to reassure the vaccinated that they have done absolutely the right thing.

Kia manuia

Assoc Prof John Dunn