Options for optimizing Slovak national vaccination strategy Vladimír Nosáľ1, Martin Smatana2, Martin Šuster3 1 Department of Neurology, Jessenius School of Medicine in Martin, Comenius University, Martin, Slovakia 2 Ministry of Education, Science, Research and Sports, Bratislava, Slovakia 3 Slovak Economic Society, Bratislava, Slovakia Abstract: The national vaccination strategy has undergone groups up to 60 years, even if they have a chronic diagnosis. several updates since its publication in December 2020. The According to the modified national vaccination strategy, these original strategy assumes priority vaccination of health groups are expected to arrive at about halfway through the professionals and other critical occupations and continues schedule, but their relative risk is average or lower despite the with priority according to age. The strategy revised in January existence of a chronic diagnosis. took more account of some chronic diagnoses, which were Conclusions: The recent modifications of the national elaborated in more detail in the March revision. Considering vaccination strategy bring a significant improvement over the limited supply of vaccine and high incidence of COVID-19 original strategy. However, we see opportunities for further cases throughout witner and early spring 2021, it was vital to optimization by considering the risks of more defined find most optimal vaccination strategy to minimize avoidable population groups, especially among groups of "younger deaths. Despite the adjustments, there is (was), especially in seniors" with co-morbidities, who could be preferred. March 2021, an opportunity to reduce the relative mortality Furthermore, the algorithm can be used to set most optimal index we develop by a few percentage points, using available vaccination strategy not only at national, but also at regional data and resources. level, up to the detail of individual GP practices. Similarly, Methods: We normalize the overall risk of the population to developed model can be quickly and effectively used to select the pre-vaccination status. The result is a relative mortality a risk group of the population and prioritize any type of index that considers the impact of vaccination on the medical preventive action. individual risk of death from Covid-19. When determining Results of the paper were used by health insurance companies risk groups, we consider the basic age groups, risks of some to fine-tune their vaccination priorities in spring 2021. professional or social groups and diagnoses that are according to available studies linked to greater probability of hospitalization and / or death. Altogether, 17 groups of 1 Objectives and introduction diagnoses were used in the analysis, out of which five were Slovak COVID-19 vaccination strategy was published in regarded as most at risk: acute cancer, dialysis patients, people December 2020 and has since undergone several adjustments. with organ transplants, people with Down syndrome and The original strategy prioritized health professionals and other COPD. Data on disease prevalence was taken from health critical occupations and continued with priority according to insurance companies. This enabled a detailed analysis, age. Revised strategy from January changes this approach and including regional and local implications. Only registered put greater priorities on chronic diseases, which were further vaccines were considered for modelling. expanded in March updates. Yet, considering a lack of supply Results: January modification of the vaccination strategy will of vaccines in spring 2021, further improvements could have help reduce the risk of mortality on Covid-19 by about 1.5 %. been made to improve relative mortality index. March update brings only a slight improvement. However, The aim of this paper is to present possible adjustments to there is additional 1 % for further optimization. These Slovak national COVID-19 vaccination strategy. changes can (could be) implemented during March to April, especially given the still low vaccination coverage of older Our primary goal was to adjust strategy to reduce avoidable age groups. mortality from COVID-19. The second objective was to protect the country's critical workforce to fight the Primary space for improvement is in the increase of priority pandemic. We consider a priority to vaccinate health for combinations of the oldest groups of the population with professionals, although their relative risk of dying from chronic diseases (groups among strong population years 60- Covid-19, although relatively high, is not always highest 80 years of age with combinations of chronic diagnoses). At among at-risk groups. the same time, it is possible to slightly delay younger age ______________ Copyright ©2021 for this paper by its authors. Use permitted under Creative Commons License Attribution 4.0 International (CC BY 4.0). 2 Methodology - autoimmune diseases with the administration of immunosuppressants (ATC_L04) We created a relative mortality index that considers the impact - diabetes (divided into E10 and E11) of vaccination on the individual risk of death from Covid-19 - cardiovascular diseases - heart attack in 2020 and later and compared it to each of the vaccination updates to (I21 and I22) determine their efficiency. - cardiovascular diseases - other (I05 to I52) - chronic kidney disease (N18) Process of determining risk groups, relative risks, vaccination priority settings and vaccination schedules are described in - osteoporosis (M80) following sections. - Alzheimer's disease with dementia (F00) - severe psychiatric disorders addressed in inpatient 2.1 Risk groups care - TB and mycobacteriosis (A15-A19, A31) When determining risk groups, we took into account the basic age groups 16-44, 45-59, 60-64, 65-69, 70-74, 75-79, 80- We further aggregated these patients into larger groups. We 84, and 85 and over. Furthermore, we considered the tried to create groups of patients with similar risks, which increased risk according to selected diagnoses and the risks of for practical reasons can be specifically addressed in some professional or social groups. the vaccination strategy. We selected five critical diagnoses that are the riskiest and should be addressed as a matter of The basic distribution of risk is based on the history of deaths priority: acute oncological diseases, dialysis patients, people in Slovakia as of March 2021 (IZA, 2021; ŠÚSR, with organ transplants, people with Down syndrome and 2021) In further calculations, we consider the distribution of severe chronic obstructive pulmonary disease. These are deaths in 2021, when the British strain B117 was already relatively small groups of patients with a total of 75,000 widespread in Slovakia. Taking into account the size of each people. demographic group, the relative risks of mortality were calculated. We aggregated other groups of diagnoses according to the number of diagnoses per patient with one diagnosis (without The risk of dying from Covid-19 for men is significantly the five diagnoses and among cardiovascular diagnoses only higher than for women. However, we did not consider it with past infarction), two, three or more diagnoses (including realistic to set different criteria for individual all other cardiovascular diagnoses). We also aggregate age sexes. Therefore, after aggregation, we use the following groups according to the division mentioned above. The relative risks: resulting grouping is shown in Table 1. Cardiovascular - Age group 45-59 is a reference group diseases, apart from recent heart attacks, type 1 diabetes (E10) - Group 16-44 is only 0,10 multiple of risk compared to and bronchial asthma, are only considered in combination the reference group (RR) with other diagnoses. - Category 60-64 has 3,23-fold greater risk than RR The size of risk groups is based on data publicly available as - Category 65-69 has 5,33-fold greater risk than RR of February 2020. The overall demographic data for Slovakia - Category 70-74 has a 9,00-fold greater risk than RR are as of 1 January 2020. The population structure may have - Category 75-79 has 12,88-fold greater risk than RR changed slightly, as the pandemic resulted in higher mortality, - Category 80-84 has 20,81-fold greater risk than RR especially among older groups, especially at the end of 2020. - Category 85+ has a 25,43-fold greater risk than RR We also considered the following chronic diagnoses, which according to available sources have a significantly higher 2.2 Relative risk risk (CDC, 2021; PHE, 2021; Semenzato et al. 2021). The basic relative risks by age are based on current data on - oncological - in active treatment (new cases per year, mortality from Covid-19 in Slovakia. We used the statistics of diagnosis C00-C99) deaths on Covid-19 until 12.1.2021 (ŠÚSR, 2021). We also - dialyzed (Z49) took into account the expected loss of life for each age - transplantation (kidneys, heart, liver, pancreas, lungs - group. The risk of death from Covid-19 increases with age diagnosis Z94) significantly faster than the average life expectancy for - Down syndrome (Q90) each age group decreases. The order of risk as well as taking - chronic obstructive pulmonary disease (severe forms: into account the potential loss of years of life remains the same J44.00, J44.01, J44.10, J44.11, J44.80, J44.81, J44.90, - except for a group of 85+, which is due to the low life J44.91) expectancy behind a group of seventy years old. - bronchial asthma (J45) - sickle cell disease (D57) - oncological, in monitoring (C00-C97) Number of patients in risk groups Age cohort Diagnosis ICD-10 16-44 45-59 60-64 65-69 70-74 75-79 80-84 85+ Oncological, new patients as of 2020 C00-C97 2 219 7 291 4 644 4 422 4 302 3 690 2 776 1 821 Dialysis Z49 615 690 631 511 676 420 225 60 Transplantation of an organ Z94 869 1 134 486 382 216 105 51 27 Down syndrome Q90 493 55 3 4 0 0 0 0 COPD J44 3 590 7 017 5 221 6 328 5 429 4 294 2 840 2 203 Other chronic diseases - one diagnosis 56 524 45 379 15 163 12 982 6 426 4 204 2 749 2 997 Other chronic diseases - two diagnoses 39 707 95 054 63 254 76 477 65 337 49 319 32 308 24 797 Other chronic diseases - three + diagnoses 9 243 28 379 22 451 30 121 30 373 26 474 18 506 12 933 Without a diagnosis 2 058 452 918 450 248 060 198 178 118 482 71 343 41 649 38 738 Table 1: Number of people in each of used risk groups; Source: NCZI (2021); OECD (2019); own calculation Age group 16-44 45-59 60-64 65-69 70-74 75-79 80-84 85+ Adjusted relative risk according to age 0,18 1,00 2,26 3,04 4,02 4,30 4,92 3,54 Table 2: Adjusted relative risk according to age; Source: IZA (2021); ŠÚSR (2021); own calculations Age group 16-44 45-59 60-64 65-69 healthcare workforce 32 000 35 000 9 000 3 000 social care employees 5 000 4 800 1 200 0 social care clients 15 000 12 000 3 000 0 soldiers, police, critical infrastructure 15 000 15 000 0 0 teachers 24 000 24 000 6 000 2 000 Table 3: Number of selected professionals and social groups according to age Source; IZA (2021); ŠÚSR (2021); own calculations Additional relative risk to the reference age group without diagnoses one chronic disease 0,6 two chronic diseases 1,5 three and more chronic diseases 3 new oncological cases, dialysis, transplants, Down, COPD 5,15 healthcare workforce 7 social care employees 1,4 social care clients 1,05 soldiers, police, critical infrastructure 0,3 teachers 0,6 Table 4: Additional relative risk to the reference age group without diagnoses; own calculations; Source: Jarkovský et al (2021), Mutambudzi et al. (2021), Semenzato et al (2021). We assumed that paramedics, teachers, and social care We recognize that taking life expectancy into account can be services staff does not suffer from combination of three or morally questionable in the provision of health care - just as more chronic diseases. We assumed that they have a similar disregarding it can be morally questionable. The resulting risk health status as the rest of the population. We assumed good weights are shown in Table 2. health without chronic diseases for members of the uniformed forces and employees of critical infrastructure. Soldiers We also included selected groups of professionals and social and police officers were more involved in testing in Slovakia groups (social care services clients under 65) who have an than in other countries, but at present the testing capacity has increased risk of infection and death on Covid-19. Their increased so that systematic assistance from the armed forces numbers and age distribution are given in Table 3. Additional is no longer so necessary. Therefore, we considered it risk for groups of chronically ill and professions is further sufficiently realistic to take estimates of increased risk from calibrated using studies by Jarkovský et al (2021), Semenzato the literature. The resulting relative risks to the 15-64 group et al. (2021) and Mutambudzi et al. (2021), shown in Table 4. are then as follows in Table 5. Relative risk / diagnosis extra risk 16-44 45-59 60-64 65-69 70-74 75-79 80-84 85+ Oncological, new patients as of 2020 4 0,76 3,27 6,39 8,31 10,08 9,94 10,93 8,43 Dialysis 4,2 0,79 3,40 6,65 8,64 10,48 10,34 11,37 8,76 Transplantation of organ 3,5 0,69 2,95 5,75 7,48 9,07 8,95 9,84 7,58 Down syndrome 16 2,59 11,13 21,73 28,24 34,27 33,80 37,16 28,65 COPD 3 0,61 2,62 5,11 6,64 8,06 7,95 8,74 6,74 Other chronic diseases - one diagnosis 0,6 0,24 1,05 2,05 2,66 3,23 3,18 3,50 2,70 Other chronic diseases - two diagnoses 1,5 0,38 1,64 3,20 4,15 5,04 4,97 5,47 4,21 Other chronic diseases - three + diagnoses 3 0,61 2,62 5,11 6,64 8,06 7,95 8,74 6,74 healthcare workforce 7 1,22 5,24 10,23 13,29 16,13 15,91 17,49 13,48 social care employees 1,4 0,37 1,57 3,07 3,99 4,84 4,77 5,25 4,04 social care clients 1,05 0,31 1,34 2,62 3,41 4,13 4,08 4,48 3,45 soldiers, police, critical infrastructure 0,3 0,20 0,85 1,66 2,16 2,62 2,58 2,84 2,19 teachers 0,6 0,24 1,05 2,05 2,66 3,23 3,18 3,50 2,70 others 0 0,15 0,65 1,28 1,66 2,02 1,99 2,19 1,69 Table 5: Final relative risk indices for age groups; Source: own calculations Available data on patients contain relatively few people with In the alternative scenario, we simulated (i) the old national obesity. Most diagnoses of E66 are recorded in children, adult vaccination strategy (ii) its updated version by decree of the patients are rarely treated directly for obesity. In the data from Ministry of Health from 19th January 2021 that placed National center for healthcare information (herein as “NCZI) higher prioritization on older people and the moved members we see only 2 034 such persons. At the same time, the of the critical infrastructure into replacement group and (iii) European Health Survey shows that more than 1% of the and currently valid version of the strategy, updated by decree population has serious obesity with a BMI over 40, i.e. about of the Ministry of Health on 5th of March 2021 - 50,000 adults. However, as this is a visually obvious with prioritization, in particular according to age and without diagnosis, possibly verifiable in a few seconds, we consider it priority for members of critical infrastructure. sufficient for patients to present this diagnosis when The table below also provides assumptions as to what part of registering for vaccination, without the need for confirmation a population will eventually be vaccinated. For most groups, by the attending physician. Underweight (BMI below 18.5) it is estimated as 70% (which will require can also be considered, especially in combination with type 1 strong communication campaign, as currently diabetes. only about 55 % of the population wants to get a vaccine). For members of critical infrastructure, we assume eventually 100% vaccination, similarly to social care staff and clients, 2.3 Priority setting where vaccination may eventually be introduced as a In our basic model, the priorities for vaccination are based on condition of admission to the facility (similarly as vaccination the Table 5, organized from the highest to the lowest risk. The against influenza is currently mandatory). only change is in moving all health professionals to the For health professionals and teachers - where there is a better beginning of the schedule, in line with the objectives and awareness of SARS-COV-2, we assumed 85% participation in line with reality of vaccination in Slovakia. Given that the in vaccination. Resulting prioritization of all 4 scenarios are threat to the functioning of the economy is not that present in shown in Table 6 below. other professions due to sick leave and quarantine, we did not increase the priority for critical infrastructure. Priority Priority Propority Priority Estimated according Relative according according accoridng to Category Number vaccinatio to the Risk to the to the first the latest n rate original model update update strategy healthcare workforce; 65-69 13,29 3 000 85% 1 1 1 1 healthcare workforce; 60-64 10,23 9 000 85% 2 3 2 3 Other chronic diseases - three + diagnoses; 80-84 8,74 18 506 70% 3 2 2 2 Other chronic diseases - three + diagnoses; 70-74 8,06 30 373 70% 4 3 2 3 Other chronic diseases - three + diagnoses; 75-79 7,95 26 474 70% 5 4 2 3 Other chronic diseases - three + diagnoses; 85+ 6,74 12 933 70% 6 1 1 1 Other chronic diseases - three + diagnoses; 65-69 6,64 30 121 70% 7 3 2 3 Onko + CHOCHP + Dialyz. + Transp. + Down S 6,15 75 740 85% 8 4 2 4 Other chronic diseases - two diagnoses; 80-84 5,47 32 308 70% 9 2 2 2 healthcare workforce; 45-59 5,24 35 000 85% 10 3 2 3 Other chronic diseases - three + diagnoses; 60-64 5,11 22 451 70% 11 1 2 1 Other chronic diseases - two diagnoses; 70-74 5,04 65 337 70% 12 4 2 3 Other chronic diseases - two diagnoses; 75-79 4,97 49 319 70% 13 1 1 1 Other chronic diseases - two diagnoses; 85+ 4,21 24 797 70% 14 3 2 3 Other chronic diseases - two diagnoses; 65-69 4,15 75 148 70% 15 5 2 4 Other chronic diseases - one diagnosis; 80-84 3,50 2 749 70% 16 2 2 2 Other chronic diseases - one diagnosis; 70-74 3,23 6 426 70% 17 4 2 4 Other chronic diseases - two diagnoses; 60-64 3,20 59 534 70% 18 3 2 3 Other chronic diseases - one diagnosis; 75-79 3,18 4 204 70% 19 4 2 3 social care employees; 60-64 3,07 1 200 100% 20 3 2 3 Other chronic diseases - one diagnosis; 85+ 2,70 2 997 70% 21 5 2 4 Other chronic diseases - one diagnosis; 65-69 2,66 12 756 70% 22 1 1 1 teachers; 65-69 2,66 2 000 85% 23 4 2 4 social care clients; 60-64 2,62 3 000 100% 24 4 3 4 Other chronic diseases - three + diagnoses; 45-59 2,62 28 379 70% 25 2 2 2 others; 80-84 2,19 41 649 70% 26 5 2 7 Other chronic diseases - one diagnosis; 60-64 2,05 14 271 70% 27 1 2 4 teachers; 60-64 2,05 6 000 85% 28 3 2 3 others; 70-74 2,02 118 482 70% 29 4 2 3 others; 75-79 1,99 71 343 70% 30 6 3 4 others; 85+ 1,69 38 738 70% 31 7 3 4 others; 65-69 1,66 194 733 70% 32 4 2 4 Other chronic diseases - two diagnoses; 45-59 1,64 88 250 70% 33 5 2 7 social care employees; 45-59 1,57 4 800 100% 34 1 1 1 social care clients; 45-59 1,34 12 000 100% 35 1 2 7 others; 60-64 1,28 230 472 70% 36 8 4 4 healthcare workforce; 16-44 1,22 32 000 85% 37 6 4 7 Other chronic diseases - one diagnosis; 45-59 1,05 42 131 70% 38 9 3 7 teachers; 45-59 1,05 24 000 85% 39 1 1 1 soldiers, police, critical infrastructure; 45-59 0,85 15 000 100% 40 10 1 7 others; 45-59 0,65 840 703 70% 41 10 4 7 Other chronic diseases - three + diagnoses; 16-44 0,61 9 243 70% 42 5 2 11 Other chronic diseases - two diagnoses; 16-44 0,38 38 306 70% 43 5 2 11 social care employees; 16-44 0,37 5 000 100% 44 1 1 1 social care clients; 16-44 0,31 15 000 100% 45 1 2 11 Other chronic diseases - one diagnosis; 16-44 0,24 54 530 70% 46 6 3 11 teachers; 16-44 0,24 24 000 85% 47 9 3 11 soldiers, police, critical infrastructure; 16-44 0,20 15 000 100% 48 11 1 11 others; 16-44 0,15 1 970 846 70% 49 11 4 11 Table 6: Prioritisation of vaccination, in 4 calculated scenarios; Source: own calculations 2.4 Vaccination schedule For vaccination, we assumed deliveries according to publicly available information published in daily press. We only took 1st dose into account already approved BionNTech / Pfizer, Moderna P+M+AZ and AstraZeneca vaccines. For the first two vaccines, we 30,000 7,000,000 2nd dose expect a period between two doses of 4 weeks. For P+M+AZ+ AstraZeneca, we modelled a 10-week period between the two JJ Together 6,000,000 doses. This vaccine is only for people under 70 years of age. If 25,000 2. dose the model allows multiple vaccines to be administered at the same time, BioNTech / Pfizer or Moderna will be used 5,000,000 first, followed by AstraZeneca. At the same time, we assumed 20,000 that from the supplied vaccines, a reserve for the second dose is always left for those who have already received the first 4,000,000 dose. We also assume that all available vaccines will be used 15,000 without loss. 3,000,000 The amounts of published doses are used in the model so that the delivered vaccine is consumed evenly before the next 10,000 delivery (postponing half of the vaccines to the 2nd dose). The 2,000,000 model did not include the Johnson & Johnson vaccine, but it is relatively easy to expand it with this option. We have not 5,000 yet included it due to uncertainty about the delivery 1,000,000 schedule. Uncertainty about vaccine supply assumptions is, of course, 0 0 great. Accelerating delivery would improve the results of our model in all scenarios, as well as the approval of the Astra Zeneca vaccine in all age groups, or possibly others. The delay acts in the opposite direction. However, the Figure 2: Estimated daily vaccination rate; Source: own calculations March qualitative results of the model remain unchanged. 2021 12,000,000 BioNTech/Pfizer Moderna 2.5 Simulation Astra-Zeneca Johnson & Johnson 10,000,000 For each of the scenarios, we simulated the results as follows: - Available vaccines were divided to groups according to priority, until the group for each charged with the 8,000,000 expected coverage rate (as shown in Table 6). When a quota was filled for a priority group, we moved the vaccination to the next group in sequence. - We only used AstraZeneca to people under 70 years of 6,000,000 age. - The second dose was expected 28 days after the first dose with mRNA vaccines or after 70 days with 4,000,000 AstraZeneca - For persons vaccinated with the first dose we expected a reduction in their level of risk and by 72 %. After a 2,000,000 second dose of the protections 99 % (Dagan et al. , 2021) . - This is how we adjusted the relative risk of people who have already been vaccinated. We could then calculate 0 1/1/211/2/211/3/211/4/211/5/211/6/211/7/211/8/211/9/211/10/21 1/11/21 1/12/21 the total risk as a weighted sum according to the number of people in each group and their original (Table 5) or by Figure 1: Estimation of vaccine deliveries (doses); Source: own calculations vaccination reduced relative risk. March 2021 - We assumed that vaccination with one dose reduces the According to the modified national vaccination strategy, these risk of transmitting the infection by 50% and increases groups are expected to arrive at about halfway through the to 80% after the second dose. schedule, but their relative risk is average or lower despite the - We normalized the overall risk of the population to the existence of a chronic diagnosis. pre-vaccination status. The result was a relative Our results should be taken as a threshold result, if it would mortality index. This index considered in particular be possible to mobilize all sensitive groups in the right the impact of vaccination on the individual risk of death order completely effectively. As in practice the vaccination of of individuals in Covid-19. We also considered some groups will be extended and members of critical reducing the number of susceptible individuals after infrastructure or members of less sensitive groups will be vaccination. On the other hand, it is also likely that vaccinated as substitutes, the decline of the curves will society will respond by releasing the severity of be slightly slower than shown in Figure 3. However, measures and discipline of the population. We did not qualitative differences will be maintained. dare to estimate the resulting effect of these opposing epidemiological factors. However, it is highly likely that For a better numerical comparison, we calculated the area even by the end of 2021, collective immunity will not be under the curve from Figure 3. Since the curves are levelling achieved, and the spread of the pandemic will not at about 1/3 of the original risk at the end of 2021 (which is stop. understandable, as we assume that almost 30% of the population cannot be vaccinated and vaccination efficiency is 4 Results not fully 100%), we calculate the content under the curve by 30.6.2021. Figure 4 shows that a modification of the The result of the simulation is shown in Figure 3. We see that vaccination strategy of 19.1.2021 will help reduce the risk of the modified national vaccination strategy is a significant step mortality on Covid-19 by about 1.5 % . However, we see forward from the original strategy. The current version of the further room for optimization by about 1 %. These changes strategy is only a slight improvement compared to January could have been implemented during March to update. Vaccination will reach high-risk groups 85+, 80-84 April, especially given the still low vaccination coverage and other senior groups of the population faster. However, of older age groups. this strategy can be further optimized based on our The use of these opportunities would require consideration of results. Specifically, it is recommended to increase priorities several criteria in determining order of vaccination for combinations of the oldest groups of the population and effective use of large data sources of our health with chronic diseases (groups aged 60-80 with combinations information systems, cooperation with the attending doctors of chronic diagnoses) . At the same time, it is possible to and flexible ordering system. postpone slightly younger age groups up to 60 years, even if they have a chronic diagnosis, or a combination of diagnoses in the younger age groups. 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% 1/1/21 1/2/21 1/3/21 1/4/21 1/5/21 1/6/21 1/7/21 1/8/21 1/9/21 1/10/21 1/11/21 1/12/21 Priority according to the model Propority according to the first update Priority according to the original strategy podiel neočkovanej populácie (2 dávky) Priority accoridng to the latest update Figure 3: Relative mortality according to modelled scenarios; Source: own calculations 70% 60% 60.4% 62.3% 63.7% 62.2% 50% 40% 30% 20% 10% 0% Priority according to the model Propority according to the first Priority according to the original Priority accoridng to the latest update strategy update Figure 4: Reduction in relative mortality in all scenarios; Source: own calculations Jarkovský, J., Benešová, K., Cerny, V. et al. (2021) Covidogram as 5 Conclusion a simple tool for predicting severe course of COVID-19: population- Proposed modification of the national vaccination strategy based study. BMJ Open. London: BMJ Publishing Group, 2021, vol. 11, No 2, p. 1-7. ISSN 2044-6055. brings a significant improvement over the original strategy. However, we see opportunities for further IZA (2021) Inštitút zdravotných analýz: github COVID-19 data. optimization by taking into account the risks of more defined https://github.com/Institut-Zdravotnych-Analyz/ population groups, especially among groups of "younger covid19-data seniors" with co- morbidities who could be preferred. Taking Mutambudzi M, Niedzwiedz C, Macdonald EB, et al (2021) advantage of these opportunities requires better handling Occupation and risk of severe COVID-19: prospective cohort study of data on the health status of the population, which is already of 120 075 UK Biobank participants. Occupational and available to the public sector, as well as greater flexibility of Environmental Medicine 2021;78:307-314. the ordering system and cooperation with attending physicians resp. patients' health insurance companies. NCZI (2021) Národné centrum zdravotníckych informácií: dávky zdravotných poisťovní. Our approach also allows for flexible division into multiple http://www.nczisk.sk/Statisticke_vystupy/Tematicke_statisticke_vy groups by age, occupation, or diagnosis - which proves to be stupy/Pages/default.aspx practical when opening vaccination options to other groups, where we have observed the exhaustion of available OECD (2019). OECD/European Observatory on Health Systems and dates within minutes. We also demonstrate that grouping by Policies. Slovak Republic: Country Health Profile 2019, State of diagnosis is possible using existing data in NCZI Health in the EU, OECD Publishing, Paris/European Observatory on databases. Therefore, it would not be necessary to request Health Systems and Policies, confirmation from physicians from the vast majority of Brussels, https://doi.org/10.1787/c1ae6f4b-en. patients with chronic diagnoses, automatic verification of the PHE (2021) Public Health England: Guidance on shielding and registration system in the NCZI database is sufficient. protecting people who are clinically extremely vulnerable from Furthermore, the algorithm can be used to set most optimal COVID-19. vaccination strategy not only at national, but also at regional https://www.gov.uk/government/publications/guidance-on- level, up to the detail of individual GP practices. Similarly, shielding-and-protecting-extremely-vulnerable-persons-from-covid- developed model can be quickly and effectively used to select 19/guidance-on-shielding-and-protecting-extremely-vulnerable- a risk group of the population and prioritize any type of persons-from-covid-19#cev medical preventive action. 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People France-Mis-en-ligne-le-09-02-21.pdf with Certain Medical Conditions. https://www.cdc.gov/coronavirus/2019-ncov/need-extra- ŠÚSR (2021) Štatistický úrad Slovenskej Republiky. precautions/people-with-medical-conditions.html DEMOGRAFIA – PRÍČINY ÚMRTÍ V SLOVENSKEJ REPUBLIKE V ROKU 2020. https://bit.ly/365cnn5 Dagan, N., Barda, N., Kepten, E., et al. (2021) BNT162b2 mRNA Covid-19 Vaccine in a Nationwide Mass Vaccination Setting. The New England Journal of Medicine, 384:1412-1423