Author(s): Tudor Arvinte
Analysis of data from the Department of Health of Northern Ireland for the period 30th August to 19th December 2021 showed significant beneficial effects of COVID-19 vaccination in reducing the percentages of COVID-19 cases admitted to hospital and COVID-19 deaths in all age cohorts of the population. In the studied period Northern Ireland had a very high percentage of population fully vaccinated against COVID-19, 77% of the population below 50 and 93% of the population over 50 years of age. As an example of the beneficial effects of vaccination, in the “60-69” age cohort the percentage hospitalised with COVID-19 was 2.40% for not vaccinated and only 0.18% for the fully vaccinated. The percentage deaths from COVID-19 for the “60-69” not vaccinated population were 0.28%, for the fully vaccinated 0.03%. Unexpectedly, the percentages of deaths from COVID-19 cases admitted to hospital were lower for not vaccinated patients in the age cohorts “18-49”, “50-59”, “60-69”, “50 and over” and “all adults”, compared to the fully vaccinated in the same age cohort: “18-49”, 2.1% deaths “not vaccinated”, 4.3% deaths “fully vaccinated”; “50-59”, 5.8% deaths “not vaccinated”, 8.1% deaths “fully vaccinated”; “60-69”, 11.9% deaths “not vaccinated”, 16.5% deaths “fully vaccinated “ and “50 and over”, 17.8% deaths “not vaccinated”, 21.7% deaths “fully vaccinated”. The difference was the highest for the “all adults” cohort: 10.5% deaths in the not vaccinated COVID-19 hospitalized patients and 20.2% deaths in the fully vaccinated group
Starting August 2021, the Ministry of Health of Northern Ireland published in the Internet documents entitled “COVID-19 in Northern Ireland - Vaccination Status of Deaths and Hospitalisations”. Four of these documents covered without overlap the period 30th August to 19th December 2021 (Weeks 35-38 [1], 39-42 [2], 43-46 [3], 47-50 [4]), showing, for different age groups, the vaccination status of the COVID-19 cases admitted to hospital (Tables 1 in [1-4]), and the number of COVID-19 deaths within 28 days of a positive test (Tables 2 in [1-4]). Addition of the data in documents [1-4] gives the total number of hospitalisations with COVID-19 and the total number of deaths from COVID-19 in Northern Ireland for the 112-day period, (Table 1). The data show that for patients over 50, the number of hospitalised cases as well as the number of deaths, is higher for the fully vaccinated cohorts [1-4]. These observations are explained in the Northern Ireland Ministry of Health documents [1-3] as follows: “These results should be interpreted in the context of vaccine coverage in the Northern Ireland population (Figures 1 and 2). The success of the vaccination programme has resulted in a very small percentage of unvaccinated individuals, particularly for the older age cohorts. When there is very high vaccine coverage in the population, even with a highly effective vaccine, it is expected that a large proportion of cases, hospitalisations and deaths would occur in vaccinated individuals. This is simply because a larger proportion of the population are vaccinated than unvaccinated and no vaccine for all cohorts (between 1.1 to 20 times less) (Table 3, Figure 1a). The “50-59” age cohort had the highest difference between “not vaccinated” and “fully vaccinated” (20 times) in the percentage hospitalisation relative to cohort’s population: 1.96% hospitalisations for “not vaccinated”, 0.1% hospitalisations for “fully vaccinated” (Table 3). The smallest difference (1.1 times) was for the “80 and over” age cohort: 1.37% hospitalisations for “not vaccinated”, 1.22% hospitalisations for “fully vaccinated” (Table 3).
As expected, significant beneficial effects of COVID-19 vaccination were observed in reducing the percentages of COVID-19 deaths for all cohort populations. The % deaths relative to the population of the cohort was smaller in the “fully vaccinated” groups (2 to 11 times less) and (1.2 to 6 times less) in the “one dose only” groups (Table 3, Figure 1b). The highest beneficial effects of vaccination were in the “50-59” age cohort where the “fully vaccinated” had an 11 times lower % deaths relative to population compared to the “not vaccinated”.
Unexpectedly, for the age cohorts “18-49”, “50-59”, “60-69”, and “50 and over” the percentages of deaths were lower for the not vaccinated COVID-19 patients admitted to hospital when compared to fully vaccinated hospitalised: “18-49”, 2.1% deaths “not vaccinated”, 4.3% deaths “fully vaccinated”; “50-59”, 5.8% deaths “not vaccinated”, 8.1% deaths “fully vaccinated”; “60-69”, 11.9% deaths “not vaccinated”, 16.5% deaths “fully vaccinated“ and “50 and over”, 17.8% deaths “not vaccinated”, 21.7% deaths “fully vaccinated” (Table 1, Figure 1c). The difference was the highest for the “all adults” cohort: 10.5% of not vaccinated who were hospitalised died, compared to 20.2% of fully vaccinated hospitalised who died (Table 1, Figure 1c).
Only for the age cohorts “70-79” and “80 and over” the percentage deaths from COVID-19 in hospitalised patients was smaller for the “fully vaccinated” and “one dose only” when compared to the “not vaccinated” from the same cohorts (Table 1). However, the percentage deaths for the elderly population were high: in the “70- 79” age cohort 18.9% died from “fully vaccinated” hospitalised patients, and 25.0% died from the “not vaccinated” hospitalised patients; in the ”80 and over” age group 30.0% died from the “fully vaccinated” hospitalised patients and 53.2% died from not vaccinated hospitalised patients (Table 1, Figure 1c).
The COVID-19 cases in Northern Ireland during the studied period, (30th August - 19th December 2021), were mainly the Delta corona virus variant. Only data from report [4], covering the period 22nd November to 19th December, could include Omicron infections [4]. The Omicron variant was first reported from South Africa on 24th November 2021[7] and in the United Kingdom on 13th December, when it was 9.4% of all variants, reaching 65.6% on 27th December 2021 [7, 8]. Northern Ireland had a very high percentage of population fully vaccinated against COVID-19: 77% of the population below 50 and 93% of the population over 50 (Table 2). The vaccines used were Pfizer/BioNTech (51.2%), AstraZeneca (47%) and Moderna (1.8%) [5].
In all age cohort populations, the percentages of hospitalisation with COVID-19 and of death from COVID-19 were smaller for the “fully vaccinated” and “one dose only” groups, compared to the “not vaccinated” (Figures 1a, 1b). It was unexpected that for hospitalised patients the number of deaths for the “not vaccinated” cohorts was lower compared to the “fully vaccinated” in the age groups “18-49”, “50-59”, “60-69”, “50 and over”, and in “all adults” (Table 3, Figure 1c). Although referring to infection and not death, for the Omicron variant it was recently reported that fully COVID-19 vaccinated patients were 42% less protected from infection (-42% vaccine efficacy) compared to not vaccinated [9].
One possible explanation for the increased number of COVID-19 deaths in fully vaccinated hospitalised patients may be the development of COVID-19 vaccination associated adverse immune responses such as vaccine-associated enhanced disease (VAED) and vaccine-associated enhanced respiratory disease (VAERD). The possible adverse events VAED and VAERD are under ongoing vaccine regulatory surveillances. For all mRNA and DNA COVID-19 vaccines approved by the European Medicines Agency, VAED and VAERD are included in the Risk Management Plans [10-13]. For example, in the Pfizer/ BioNTech Risk Management Plans from 25 November 2021, VAED, including VAERD, is considered the only “important potential risk”, Module SVII.1.2. in [10] “Although not observed or identified in clinical studies with COVID-19 vaccines, there is a theoretical risk, mostly based on non-clinical betacoronavirus data, of VAED occurring either before the full vaccine regimen is administered or in vaccinees who have waning immunity over time. If VAED were to be identified as a true risk, depending on its incidence and severity, it may negatively impact the overall vaccine benefit risk assessment for certain individuals” [10]. And, in Table 5 from the Pfizer/BioNTech RMP [10] the conclusions are: “VAED may present as severe or unusual clinical manifestations of COVID-19, overall, there were 425 subjects with confirmed COVID-19 following one or both doses of the vaccine; 288 of the 425 cases were severe, resulting in hospitalization, disability, life threatening consequences or death. None of the 288 cases could be definitively considered as VAED/VAERD. The review of subjects with COVID-19 following vaccination, based on the current evidence, VAED/VAERD may remain a theoretical risk for the vaccine. Surveillance will continue” [10].
The observed increased number of COVID-19 deaths in “fully vaccinated” hospitalised patients could have other possible origins besides the theoretical risk of VAED/VAERD, stimulating hypotheses and questions such as: i) for the same age cohort are there differences between the “not vaccinated” and “fully vaccinated” patients in their general health and underlying diseases?; ii) are there vaccine-type differences in the deaths in “fully vaccinated” hospitalised patients? iii) could medical treatments be adapted to age groups to improve the survival rates?; iv) are there patient pre-existing conditions (e.g. asthma) which may contribute to the observed effects?
Further analysis of COVID-19 deaths in hospitalised patients, similar to the one presented here for Northern Ireland, together with medical and immunological investigation, will help to understand the relations between vaccination, hospitalisation and deaths for COVID-19 patients and may contribute to the development of better vaccines and therapies.
An overview of the data analysis performed in this paper is presented in the Summary Boxes in Table 4. The box representation permits a fast, easy way to compare in each age cohort the not vaccinated and fully vaccinated groups. It enables non-specialists to evaluate the risks of COVID-19 disease and the benefits of vaccination.
| Number of Hospitalisations and Deaths in Northern Ireland Between 30th August and 19th December 2021 | ||||||||||
| Age Cohort | Time Period Week | Number of Patients Hospitalised with COVID-19 | Number of Patients Who Died from COVID-19 | % Deaths from COVID-19 from Hospitalised Patients | ||||||
| Not Vaccinated | First Dose Only | Fully Vaccinated | Not Vaccinated | First Dose Only | Fully Vaccinated | Not Vaccinated | First Dose Only | Fully Vaccinated | ||
| 18-49 | 35-38 | 176 | 13 | 38 | 4 | 0 | 1 | 2.30 | 0.0 | 2.6 |
| 39-42 | 136 | 6 | 37 | 3 | 0 | 1 | 2.2 | 0.0 | 2.7 | |
| 43-46 | 101 | 4 | 55 | 3 | 0 | 3 | 3.0 | 0.0 | 5.5 | |
| 47-50 | 117 | 6 | 54 | 1 | 0 | 3 | 0.9 | 0.0 | 5.6 | |
| Total | 530 | 29 | 184 | 11 | 0 | 8 | 2.1 | 0.0 | 4.3 | |
| 50-59 | 35-38 | 56 | 7 | 63 | 6 | 2 | 1 | 10.7 | 28.6 | 11.1 |
| 39-42 | 54 | 7 | 50 | 2 | 2 | 2 | 3.7 | 28.6 | 4.0 | |
| 43-46 | 54 | 6 | 53 | 2 | 0 | 5 | 3.7 | 0.0 | 9.4 | |
| 47-50 | 59 | 2 | 56 | 3 | 0 | 4 | 5.1 | 0.0 | 7.1 | |
| Total | 223 | 22 | 222 | 13 | 4 | 18 | 5.8 | 18.2 | 8.1 | |
| 60-69 | 35-38 | 64 | 5 | 79 | 5 | 1 | 13 | 7.8 | 20.0 | 16.5 |
| 39-42 | 43 | 4 | 56 | 3 | 0 | 13 | 7.0 | 0.0 | 23.2 | |
| 43-46 | 29 | 3 | 115 | 9 | 0 | 15 | 31.0 | 0.0 | 13.0 | |
| 47-50 | 41 | 5 | 60 | 4 | 1 | 10 | 9.8 | 20.0 | 16.7 | |
| Total | 177 | 17 | 310 | 21 | 2 | 51 | 11.9 | 11.8 | 16.5 | |
| 70-79 | 35-38 | 39 | 16 | 196 | 10 | 3 | 50 | 25.6 | 18.8 | 25.5 |
| 39-42 | 27 | 3 | 182 | 10 | 0 | 15 | 37.0 | 0.0 | 8.2 | |
| 43-46 | 32 | 7 | 180 | 5 | 2 | 37 | 15.6 | 28.6 | 20.6 | |
| 47-50 | 34 | 2 | 81 | 8 | 4 | 19 | 23.5 | 1- | 23.5 | |
| Total | 132 | 26 | 639 | 33 | 5 | 121 | 25.0 | 19.2 | 18.9 | |
| 80 & over | 35-38 | 19 | 18 | 251 | 12 | 4 | 70 | 63.2 | 22.2 | 27.9 |
| 39-42 | 17 | 15 | 194 | 9 | 4 | 52 | 52.9 | 26.7 | 26.8 | |
| 43-46 | 20 | 8 | 213 | 11 | 5 | 76 | 55.0 | 62.5 | 35.7 | |
| 47-50 | 23 | 3 | 126 | 10 | 6 | 37 | 43.5 | - | 29.4 | |
| Total | 79 | 41 | 784 | 42 | 13 | 235 | 53.2 | 31.7 | 30.0 | |
| 50 & over | 35-38 | 178 | 46 | 589 | 33 | 10 | 140 | 18.5 | 21.7 | 23.8 |
| 39-42 | 141 | 29 | 482 | 24 | 6 | 82 | 17.0 | 20.7 | 17.0 | |
| 43-46 | 135 | 24 | 561 | 27 | 7 | 133 | 20.0 | 29.2 | 23.7 | |
| 47-50 | 157 | 7 | 323 | 25 | 1 | 70 | 15.9 | 14.3 | 21.7 | |
| Total | 611 | 106 | 1955 | 109 | 24 | 425 | 17.8 | 22.6 | 21.7 | |
| All Adults | 35-38 | 354 | 59 | 627 | 37 | 10 | 141 | 10.5 | 16.9 | 22.5 |
| 39-42 | 277 | 35 | 519 | 27 | 6 | 83 | 9.7 | 17.1 | 16.0 | |
| 43-46 | 236 | 28 | 616 | 30 | 7 | 136 | 12.7 | 25.0 | 22.1 | |
| 47-50 | 274 | 13 | 377 | 26 | 1 | 73 | 9.5 | 7.7 | 19.4 | |
| Total | 1141 | 135 | 2139 | 120 | 24 | 433 | 10.5 | 17.8 | 20.2 | |
Table 1: The numbers of patients hospitalised with COVID-19 and the numbers of those who have died from COVID-19 in Northern Ireland between 30th August and 19th December 2021 are from Tables 1 and 2 in [1- 4]. The “Total” numbers in the table were calculated. For the period “Weeks 47-50” the numbers of “First Dose Only” for “70-79” and “80 and over” (in italics, underlined) were not considered, are likely typing mistakes in [4], i.e., the number of deaths in hospital is tabulated as larger than the number of persons hospitalised. Also, we included in the period “Weeks 47-50” in the “Fully Vaccinated” groups the “Fully Vaccinated + Booster or Dose 3” [4]. The numbers for adults under 50 were obtained by adding the number of cases for the age cohorts “18-29”, “30-39”, “40-49”, (Tables 1 and 2 in [1-4]). The % deaths from COVID-19 from hospitalised patients were calculated from the data
| Vaccination Status of Adult Age Groups in Northern Ireland Between 30th August and 19th December 2021 | |||||
|---|---|---|---|---|---|
| Age Cohort |
% Population N. Ireland | % First Dose Including Fully Vaccinated | % Fully Vaccinated | % One Dose Only | % Not Vaccinated |
| 18-29 | 13-9 | 76 | 67 | 9 | 24 |
| 30-39 | 13.4 | 82 | 75 | 7 | 18 |
| 40-49 | 14.6 | 90 | 80 | 1 | 10 |
| Under50 | 41.9 | 83a) | 77 | 6 | 17 |
| 50-59 | 12.0 | 95 | 93 | 2 | 5 |
| 60-69 | 9.7 | 96 | 94 | 2 | 4 |
| 70-79 | 6.3 | 96 | 94 | 2 | 4 |
| 80 & Over | 3.8 | 92 | 89 | 3 | 8 |
| 50 & Over | 31.8 | 95 | 93 | 2 | 5 |
| All Adults | 73.7 | 88 | 84 | 4 | 12 |
Table 2: Mean % values of vaccinations status for different age groups of Northern Ireland?s adult population in the period 30th August through 19th December 2021 (Weeks 35 to 50). Column 2: Northern Ireland population is about 1.9 million; the % population for the age groups are from [14]. Columns 3 and 4: cumulative percentages of “% First Dose Including Fully Vaccinated“ and “% Fully Vaccinated” were calculated from Figures 1 and 2 in [4]. Data in columns 5 and 6 were calculated from columns 3 and 4. Column 5: (“% One Dose Only”) = (“% First Dose Including Fully Vaccinated”) ? (“% Fully Vaccinated”). Column 6: (”% Not Vaccinated”) = 100 - (“% First Dose Including Fully Vaccinated”). For the broad age groups “Under 50”, “50 and over” the weighted arithmetic mean of the % values of vaccinations status (V) were calculated with the formula: V = (V1 P1 +V2 P2 + V3 P3 )/(P1 +P2 +P3 ) where V1 , V2 , V3 are the mean % values for the vaccination of the small age groups contained in the broad age group, and P1, P2, P3 are the corresponding percentages of the small age groups in the country’s population.
a) V (first dose “under 50”) = ((76x13.9)+(82x13.4)+(90x14.6))/(13.9+13.4+14.6) = 82.8% The weighted arithmetic mean for “All Adults” was calculated from the weighted arithmetic means of the “Under 50”, and “50 and over” age cohorts.
| Percentages of Hospitalisations and Deaths from Age Cohort Population | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Age Cohort | % Hospitalisation with COVID-19 from Age Cohort Population | % Deaths from COVID-19 from Age Cohort Population | % Deaths from COVID-19 from Hospitalised Patients | ||||||
| Not Vaccinated | First Dose Only | Fully Vaccinated | Not Vaccinated | First Dose Only | Fully Vaccinated | Not Vaccinated | First Dose Only | Fully Vaccinated | |
| 18-49 | 0.39 | 0.06 | 0.03 | 0.010 | 0.000 | 0.001 | 2.1 | 0.0 | 4.3 |
| 50-59 | 1.96 | 0.48 | 0.10 | 0.11 | 0.09 | 0.01 | 5.8 | 18.2 | 8.1 |
| 60-69 | 2.40 | 0.46 | 0.18 | 0.28 | 0.05 | 0.03 | 11.9 | 11.8 | 16.5 |
| 70-79 | 2.76 | 1.09 | 0.57 | 0.69 | 0.21 | 0.11 | 25.0 | 19.2 | 18.9 |
| 80 and over | 1.37 | 1.89 | 1.22 | 0.73 | 0.60 | 0.37 | 53.2 | 31.7 | 30.0 |
| 50 and over | 2.02 | 0.88 | 0.35 | 0.36 | 0.20 | 0.08 | 17.8 | 22.6 | 21.7 |
| All Adults | 0.68 | 0.24 | 0.18 | 0.07 | 0.04 | 0.04 | 10.5 | 17.8 | 20.2 |
Table 3: Percentages of persons from different age groups and vaccination status who have been hospitalised with COVID-19 and of those who have died from COVID-19 in Northern Ireland between 30th August and 19th December 2021. “% Hospitalisation with COVID-19 from Age Cohort Population”, H, was calculated with the formula: H = (NrH x 100) / ((V/100) x (P/100) x C) Where NrH is the number hospitalized in the age cohort, data in Table 1; V, the mean % value for the vaccination status of the group (“Not Vaccinated”, “One Dose Only”, or “Fully Vaccinated”), in the age group, data in Table 2; P is the % age cohort in the country’s population, data in Table 2; C is the country population, 1.9 million for Northern Ireland. “% Deaths from COVID-19 from Age Cohort Population”, D, was calculated with the formula: D = (NrD x 100) / ((V/100) x (P/100) x C) NrD is the number of deaths in the age cohort, data in Table 1.
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Figure 1: a) Vaccination status and the percentages of population of age cohorts hospitalised with COVID-19. b) Vaccination status and the percentages of population of age cohorts that died from COVID-19. c) Vaccination status and the percentages of population from hospitalised patients that died from COVID-19. Data for Northern Ireland between 30th August and 19th December 2021, Table 3.
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Table 4: Summary boxes, simplified presentation per age group of the data in Table 3 on the vaccination status and the percentages of population who have been hospitalised with COVID-19 and of those who have died from COVID-19 between 30th August and 19th December 2021.
The help of Emilie Poirier with figures and Amelia Cudd with text is acknowledged.
There are no conflicts of interest to declare.
