Underestimation in Reporting Excess COVID-19 Death Data in Poland during the First Three Pandemic Waves

Beyond the sine wave: unveiling climate-driven baseline mortality cycles

The relationship between temperature and mortality is well-established, with higher mortality rates occurring in moderate climates during winter. Studies on COVID-19 and influenza-related excess deaths often assume a sine-like wave pattern for baseline mortality. This study aims to assess the accuracy of this approximation in capturing the observed mortality pattern and explore its linkage with climate. Weekly mortality data from European regions (2000-2019) were modeled using the seasonal-trend decomposition procedure based on Loess. Cycles were grouped into clusters, and underlying trends were extracted using principal component analysis. Generalized linear models assuming a sine-like pattern were used to test predictive value. Cluster analysis divided the regional cycles approximately into continental and temperate climate regions, further subdivided into oceanic and Mediterranean. While the continental region exhibited a sine-like mortality pattern, it displayed modest deviations that compounded further south. The period of elevated winter mortality became shorter but more intense, while decreased summer mortality became more pronounced yet delayed. This study improves weekly estimations of excess mortality models by providing enhanced baselines. The deviation from the sine-like approximation mirrors the idealized outbreak pattern from epidemiological models with sharper surges and more gradual declines. The results point to winter infections, impacted by acquired immunity and weather conditions, as the primary drivers of fluctuations in mortality. In warmer regions, there is an apparent shift toward a lower number of overall infections within a compressed time span.

Exploring the paradoxical nature of cold temperature mortality in Europe

While low winter temperatures are associated with increased mortality, this phenomenon has been suggested to be most severe in regions with seemingly mild winters. The study aimed to establish a temperature-based formula that could elucidate the previously ambiguous regional differences in vulnerability to low temperature. European weekly mortality data (2000-2019) were matched with meteorological data to determine for each region vulnerability to temperature decrease and the optimal temperature with lowest mortality. Regression models were developed to generalize and explain these findings considering regional temperature characteristics. Optimal temperature could be predicted based on local average summer temperature (R2 = 85.6%). Regional vulnerability to temperature decrease could be explained by combination of winter and summer temperatures (R2 = 86.1%). Regions with warm winters and cold summers showed the highest vulnerability to decrease of temperature during winter. Contrary to theories about economic disparities Eastern Europe exhibited resistance comparable to Scandinavia. The southern edges of Europe demonstrated serious low temperature vulnerability to decreased temperatures, even if temperature was relatively high around 20 °C. This suggests that the observed connection primarily reflects the modulation of the length of respiratory virus infection seasons by climate conditions, counterbalanced by varying levels of acquired immunity and the presence of heatwaves eliminating the most frail individuals. Thus, relatively low vulnerability and a flat mortality cycle in countries with harsh climates paradoxically imply the presence of threats throughout the whole year.

From respiratory diseases to nervous system disorders: Unraveling the certified causes of influenza-associated deaths in Poland from 2000 to 2019

Background

This study aims to accurately estimate influenza-associated deaths in Poland and their certified cause of death, due to significant discrepancies between official numbers and expected impact.

Methods

Excess influenza-associated mortality in Poland from 2000 to 2019 was calculated using Seasonal-Trend Decomposition Procedure based on LOESS (STL), which can detect non-linear trends and non-sinusoidal cycles. Excess mortality was then used as an explanatory variable in a model predicting monthly fluctuations of officially recorded causes of death from 2010 to 2019.

Results

A total of 142,000 conservative estimates of influenza-associated deaths were identified, representing 1.86% of overall mortality. Only 0.61% of influenza-associated deaths were officially recorded as influenza. Nearly half of certified influenza deaths were attributed to the seasonal baseline mortality, potentially doubling estimated impact based solely on influenza peaks. Influenza-associated deaths were frequently recorded as respiratory diseases (24.36%), with majority attributed to underlying conditions such as cardiovascular diseases (45.31%), cancer (9.06%), or diabetes (2.66%). Influenza-associated deaths were more commonly certified as nervous system diseases (1.84%) or mental disorders (1.04%), rather than influenza itself. There was a noticeable impact of influenza on secondary infections, such as meningococcal and gastrointestinal infections.

Conclusion

These findings highlight the importance of improved estimation for informing public health policy decisions.

Unmasking the COVID-19 pandemic prevention gains: excess mortality reversal in 2022

OBJECTIVES

The purpose of this study was to assess the long-term effectiveness of COVID-19 pandemic prevention measures in saving lives after European governments began to lift restrictions.

STUDY DESIGN

Excess mortality interrupted time series.

METHODS

Country-level weekly data on deaths were fitted to the Poisson mixed linear model to estimate excess deaths. Based on this estimate, the percentage of excess deaths above the baseline during the pandemic (week 11 in 2020 to week 15 in 2022) (when public health interventions were in place) and during the post-pandemic period (week 16 in 2022 to week 52 in 2022) were calculated. These results were fitted to the linear regression model to determine any potential relationship between mortality during these two periods.

RESULTS

The model used in this study had high predictive value (adjusted R2 = 59.4%). Mortality during the endemic (post-pandemic) period alone increased by 7.2% (95% confidence interval [CI]: 5.7, 8.6) above baseline, while each percentage increase in mortality during the pandemic corresponded to a 0.357% reduction (95% CI: 0.243, 0.471) in mortality during the post-pandemic period.

CONCLUSIONS

The most successful countries in terms of protective measures also experienced the highest mortality rates after restrictions were lifted. The model used in this study clearly shows a measure of bidirectional mortality displacement that is sufficiently clear to mask any impact of long COVID on overall mortality. Results from this study also seriously impact previous cost-benefit analyses of pandemic prevention measures, since, according to the current model, 12.2% (95% CI: 8.3, 16.1) of the gains achieved in pandemic containment were lost after restrictions were lifted.

To vaccinate or to isolate? Establishing which intervention leads to measurable mortality reduction during the COVID-19 Delta wave in Poland

Background

During the Delta variant COVID-19 wave in Poland there were serious regional differences in vaccination rates and discrepancies in the enforcement of pandemic preventive measures, which allowed us to assess the relative effectiveness of the policies implemented.

Methods

Creating a model that would predict mortality based on vaccination rates among the most vulnerable groups and the timing of the wave peak enabled us to calculate to what extent flattening the curve reduced mortality. Subsequently, a model was created to assess which preventive measures delayed the peak of infection waves. Combining those two models allowed us to estimate the relative effectiveness of those measures.

Results

Flattening the infection curve worked: according to our model, each week of postponing the peak of the wave reduced excess deaths by 1.79%. Saving a single life during the Delta wave required one of the following: either the vaccination of 57 high-risk people, or 1,258 low-risk people to build herd immunity, or the isolation of 334 infected individuals for a cumulative period of 10.1 years, or finally quarantining 782 contacts for a cumulative period of 19.3 years.

Conclusions

Except for the most disciplined societies, vaccination of high-risk individuals followed by vaccinating low-risk groups should have been the top priority instead of relying on isolation and quarantine measures which can incur disproportionately higher social costs. Our study demonstrates that even in a country with uniform policies, implementation outcomes varied, highlighting the importance of fine-tuning policies to regional specificity.

Are We Facing a Tsunami of Vaccine Hesitancy or Outdated Pandemic Policy in Times of Omicron? Analyzing Changes of COVID-19 Vaccination Trends in Poland

In this study, we analyzed Polish COVID-19 vaccination data until January 2023 from the European Centre for Disease Prevention and Control to understand individual decision making during the milder Omicron wave. Our findings show a general decline in subsequent vaccine uptake. As the number of government-provided doses increased, completion rates among certain low-risk groups dropped to less than 1%. Elderly individuals, especially those aged 70–79, showed greater adherence but also exhibited decreased interest in subsequent boosters. Healthcare workers exhibited a dramatic shift in their attitude, disregarding the recommended schedule. The overwhelming majority opted out of receiving the second boosters, while the remaining individuals adjusted their timing based on infection trends or the availability of updated boosters. Two factors positively influenced vaccination decisions: societal influence and the availability of updated boosters. Lower-risk individuals were more likely to postpone vaccination until updated boosters were available. Our findings highlight that while Polish policy aligns with international guidelines, it fails to garner significant adherence from the Polish population. Previous studies have shown that vaccinating low-risk groups resulted in more sick days due to adverse events following immunization than the days gained by preventing infection. Consequently, we advocate for the official abandonment of this policy, as its practical abandonment has already taken place, and persisting in pretending otherwise only serves to erode public trust. Therefore, we propose a shift toward treating COVID-19-like influenza with vaccination for vulnerable individuals and those who have close contact with them before the season.

Are We Facing a Tsunami of Vaccine Hesitancy or Outdated Pandemic Policy in Times of Omicron? Analyzing Changes of COVID-19 Vaccination Trends in Poland

In this study, we analyzed Polish COVID-19 vaccination data until January 2023 from the European Centre for Disease Prevention and Control to understand individual decision making during the milder Omicron wave. Our findings show a general decline in subsequent vaccine uptake. As the number of government-provided doses increased, completion rates among certain low-risk groups dropped to less than 1%. Elderly individuals, especially those aged 70-79, showed greater adherence but also exhibited decreased interest in subsequent boosters. Healthcare workers exhibited a dramatic shift in their attitude, disregarding the recommended schedule. The overwhelming majority opted out of receiving the second boosters, while the remaining individuals adjusted their timing based on infection trends or the availability of updated boosters. Two factors positively influenced vaccination decisions: societal influence and the availability of updated boosters. Lower-risk individuals were more likely to postpone vaccination until updated boosters were available. Our findings highlight that while Polish policy aligns with international guidelines, it fails to garner significant adherence from the Polish population. Previous studies have shown that vaccinating low-risk groups resulted in more sick days due to adverse events following immunization than the days gained by preventing infection. Consequently, we advocate for the official abandonment of this policy, as its practical abandonment has already taken place, and persisting in pretending otherwise only serves to erode public trust. Therefore, we propose a shift toward treating COVID-19-like influenza with vaccination for vulnerable individuals and those who have close contact with them before the season.

COVID-19-related excess mortality - an overview of the current evidence

Analysis of excess deaths, defined as the difference in the total number of deaths in an emergency compared to the number of deaths expected under normal conditions, allows a more reliable assessment of the impact on health systems caused by the global threat of SARS-CoV-2 (Severe Acute Respiratory Syndrome Coronavirus-2). So far, data for the two years of the pandemic (2020-2021) indicates the occurrence of 14.9 million excess deaths according to WHO (World Health Organization) estimates. The purpose of the analysis conducted was to define the concept and identify the causes of excess mortality during the COVID-19 pandemic. Inconsistent and unreliable death registration systems; overburdened health systems in low- and middle-income countries; reduced access to medical services for patients with health problems other than COVID-19; the introduction of social distancing and lockdown rules, which translated into increased deaths from psychiatric illnesses and addictions; political considerations and media messages that interfered with vaccination acceptance and adherence; and the additional impact of other natural disasters (hurricanes, floods, drought) were identified as the most important reasons for excess deaths occurrence. The correct identification of country-specific factors and the correct response and countermeasures taken appear crucial in terms of limiting the negative impact of the current pandemic, but also of future threats of a similar nature, in order to reduce excess deaths.

Correlation between religion, spirituality and perception of healthcare services utilisation in Poland during COVID-19 pandemic

Background

The worldwide transmission of SARS CoV-2 caused the COVID-19 pandemic and had an impact on healthcare provision. The disruption of reliance on the health system during the COVID-19 pandemic posed a clear threat to public trust. Religiosity, like spirituality, is believed to have a positive influence on people's lives, enabling them to cope with illness, stress, and sudden life changes. In practice, although the terms religiosity and spirituality have similar meanings and are related, they are not identical concepts. The aim of this study is to compare the perceptions of the accessibility and quality of healthcare services provided before and during the COVID-19 pandemic in Poland by religious/spiritual people compared to those for whom religion and spirituality have little or no importance in their lives.

Methodology

This cross-sectional study was based on the authors' questionnaire, carried out during the third wave of the COVID-19 pandemic in Poland. Participants in the study were people living in various regions of Poland over 18 who were willing to complete the questionnaire voluntarily. The number of people sampled was two hundred and sixty-four. Convenience sampling method was used for this study. Statistical calculations were performed using Statistica 13 software from TIBCO and PQStat from PQStat Software and were based on the Kruskal-Wallis test, multiple regression model, the chi2 test of independence or the Mann-Whitney test. The result was considered statistically significant when p < α. The significance level was taken as α = 0.05.

Results

Two hundred and sixty-three respondents answered the questionnaire. Among them, 181 (69%) were women, and 82 (31%) were men. It was shown that religion is more important for women than for men and women who report a high role of religion in their lives rated the quality of healthcare services better before and during the COVID-19 pandemic. It was also concluded that religious people for whom religion played a major role and those who were helped by spiritual life rated accessibility and quality higher both before and during the pandemic.

Conclusions

Religious/spiritual people, through their more positive attitudes towards the world, were thought to rate access and quality of healthcare services better. Regardless of religious affiliation, the help of spiritual life during the pandemic or the importance of religion in life in all respondents, perception of healthcare services utilisation were decreased by the pandemic. This prompts thoughts on the implementation of spiritual assistance as a supportive measure to mitigate the effects of the pandemic.

More Time, Carrot-and-Stick, or Piling Coffins? Estimating the Role of Factors Overcoming COVID-19 Vaccine Hesitancy in Poland and Lithuania in the Years 2021–2022

In this study, motivation for late (from 2021-W22, i.e., 24 July 2021) uptake of the first dose of the COVID-19 vaccine among adults in Poland and Lithuania is indirectly measured in order to avoid social-desirability bias or rationalisation in retrospect of prior decisions. Weekly vaccine uptake is modeled as if vaccine hesitant people were late adopters of a new product, with a fitted non-linear trend representing steadily decreasing interest. Before the analysed period, the vaccine uptake among Polish and Lithuanian adults was almost identical. Vaccination simply explainable by the trend was responsible for the vaccination of an additional 19.96% and 19.06% adults, respectively. The fear incurred by spikes in consecutive waves of infection motivated 3.20% and 3.89% more people, respectively, while the COVID-19 passport, introduced only in Lithuania, convinced an additional 13.98% of the overall population. The effect of the COVID passport was the biggest in the 18–24 age group, and the least visible among people aged 80 or more. In the latter group, other factors also had a limited impact, with merely 1.32% tempted by the one-time €100 payment offered to everybody aged 75 or more.

Am I Paid Well Enough to Be Diagnosed with COVID-19? Determinants of Gender Differences in Infection Detection Rate among Polish Working Age Population

In comparison to Western European countries, Poland had a relatively lower percentage of its population diagnosed with COVID-19. Moreover, even the detected cases were not showing any pattern consistent with the expected chance of infection and were at best only remotely related to the severity of the illness that is known to increase with age. Instead, the crucial factor in detecting illness was whether the individual was likely to receive adequate compensation for being confined to their home, with employed women being the most likely to be diagnosed. In every Polish sub-region (powiat), in the 25–54 age group, the share of men diagnosed with COVID-19 was lower than that of women, with the missing share ranging from 8% to 36%. Based on the regression model (adjusted R² = 43.9%), there were relevant non-economic factors such as education, vaccination rate and increasing median age that were reducing this gap. However, the key factors, such as the share of population entitled to sick leave derived from employment rate, or the share of the self-employed population who were unlikely to receive adequate compensation, were related to economic incentives. It would seem that gender differences, in reaction to economic stimuli, widened the discrepancies, as the same factors were affecting women as well. While the testing rates in Poland, the lowest of all the EU countries, clearly played a role in creating the environment in which testing was perceived by the general population as somewhat optional, Polish citizens themselves through their actions aggravated the problem further, creating the impression of people receiving inadequate or no compensation for their time of self-isolation. In spite of well-intentioned government efforts to extend compensation to at least some groups, a significant share of the population clearly behaved as if they feared self-isolation more than the actual virus. Therefore, for both compliance and fairness purposes, both the severity of restrictions and the availability of compensation should be reconsidered.

Better Late Than Never: Predictors of Delayed COVID-19 Vaccine Uptake in Poland

In this study, regression models were created to explain the increase of COVID-19 vaccination rates in 378 Polish sub-regions. In order to trace the factors that could explain the willingness to delay vaccination, vaccination rates were compared for age groups of 20 years and more for 30 June 2020 and 31 January 2021. Initially high vaccination rates, rather than leading to the gradual exhaustion of the pool of those wishing to get vaccinated, were a very good predictor of the share of the remainder willing to do so, which increased the divergence between sub-regions in nominal vaccination rates. Support for Eurosceptic and anti-establishment parties was a strong predictor of persistent vaccine hesitancy. Ideological divergence from the mainstream appeared to reinforce vaccine hesitancy, and this relationship remained highly relevant even when controlling for possible time or spatial lag. Markers of social inclusion and social capital—voter turnout and employment rate—remained statistically significant even when controlling for time lag, thus implying clear relevance of trust in the public message. The share of the population with higher education remained a highly relevant factor as well, though in the 20–39 age bracket it predicted a higher vaccination rate, while in all older brackets it was a negative predictor—this implies that those people had already made up their minds. Delaying vaccination seems predominantly explainable by political views, as well as social exclusion and the historical specificity of sub-regions. On a regional level, there was actually a paradoxical Spearmans Rho correlation (0.641) between the share of population refusing mandatory vaccination for kids and the percentage of people receiving a COVID-19 vaccine, which further undermines the idea that overall observed vaccine hesitancy was in any meaningful way affected by anti-vaccine movements.

Better Late Than Never: Predictors of Delayed COVID-19 Vaccine Uptake in Poland

In this study, regression models were created to explain the increase of COVID-19 vaccination rates in 378 Polish sub-regions. In order to trace the factors that could explain the willingness to delay vaccination, vaccination rates were compared for age groups of 20 years and more for 30 June 2020 and 31 January 2021. Initially high vaccination rates, rather than leading to the gradual exhaustion of the pool of those wishing to get vaccinated, were a very good predictor of the share of the remainder willing to do so, which increased the divergence between sub-regions in nominal vaccination rates. Support for Eurosceptic and anti-establishment parties was a strong predictor of persistent vaccine hesitancy. Ideological divergence from the mainstream appeared to reinforce vaccine hesitancy, and this relationship remained highly relevant even when controlling for possible time or spatial lag. Markers of social inclusion and social capital—voter turnout and employment rate—remained statistically significant even when controlling for time lag, thus implying clear relevance of trust in the public message. The share of the population with higher education remained a highly relevant factor as well, though in the 20–39 age bracket it predicted a higher vaccination rate, while in all older brackets it was a negative predictor—this implies that those people had already made up their minds. Delaying vaccination seems predominantly explainable by political views, as well as social exclusion and the historical specificity of sub-regions. On a regional level, there was actually a paradoxical Spearmans Rho correlation (0.641) between the share of population refusing mandatory vaccination for kids and the percentage of people receiving a COVID-19 vaccine, which further undermines the idea that overall observed vaccine hesitancy was in any meaningful way affected by anti-vaccine movements.