Were mortality rates already low before vaccines were introduced

1. Summary of the results

The evidence overwhelmingly contradicts the claim that mortality rates were already low before vaccines were introduced. Multiple comprehensive studies demonstrate that vaccine-preventable diseases caused substantial mortality prior to vaccination programs.

The most compelling evidence comes from historical analysis showing that mortality from vaccine-preventable diseases declined by more than 99% for many diseases after vaccine implementation ^[1]. This dramatic reduction indicates that pre-vaccine mortality was indeed substantial, not low. The same findings are corroborated by additional research confirming that mortality from vaccine-preventable diseases was markedly reduced after vaccine implementation ^[2].

Global data further reinforces this pattern, with studies documenting 700,000 child deaths from vaccine-preventable infections before widespread vaccination programs ^[3]. This represents a significant mortality burden that existed prior to vaccine introduction.

COVID-19 specific data provides additional context. Hospital mortality data from Madrid shows an overall in-hospital COVID-19 mortality rate of 12.9% from March 2020 to April 2021, before vaccine rollout ^[4]. Importantly, these mortality rates remained stable across three pandemic waves, indicating that mortality did not naturally decline without vaccination intervention.

The effectiveness of vaccines in reducing mortality is demonstrated through multiple mechanisms. Research shows high vaccine effectiveness against COVID-19 mortality, though this effectiveness decreases over time, particularly for older populations ^[5]. Studies using novel measurement approaches found substantial waning of two-dose protection against mortality over time, especially for those aged 60+, while boosters provide important additional protection ^[6].

State-level analysis in the United States reveals a clear temporal pattern: higher mortality during the pre-Delta period (before mass vaccination) and a marked reduction in excess deaths during the Delta/Omicron wave when vaccination rates were high ^[7]. This timeline directly correlates vaccine availability with mortality reduction.

2. Missing context/alternative viewpoints

The original question lacks important nuance about different types of mortality and disease contexts. While the sources primarily focus on vaccine-preventable diseases and COVID-19, they don't address whether the question refers to overall mortality rates from all causes or specifically vaccine-preventable diseases.

Temporal and geographical variations are also missing from the original question. Research reveals complex relationships between vaccination rates and mortality rates across over 150 countries, with studies finding that a 1% increase in full vaccination was linked to a 0.7% rise in expected deaths per 100,000 people ^[8]. This suggests that factors beyond vaccination play a significant role in determining mortality rates, including socioeconomic and environmental elements.

The question also fails to acknowledge methodological limitations in mortality studies. Research notes challenges including incomplete vaccination registration and lack of data on previous SARS-CoV-2 infections ^[5], which can affect the accuracy of mortality assessments.

Selection effects represent another missing perspective - studies have developed novel measures like COVID Excess Mortality Percentage (CEMP) to evaluate vaccine effectiveness while controlling for selection effects in who gets vaccinated ^[6]. This indicates that simple mortality comparisons may not capture the full picture without accounting for demographic and behavioral differences between vaccinated and unvaccinated populations.

3. Potential misinformation/bias in the original statement

The original question contains an implicit assumption that may promote vaccine hesitancy by suggesting that vaccines were unnecessary because mortality was already declining. This framing ignores the substantial historical evidence of vaccine impact.

The question demonstrates survivorship bias by potentially focusing on recent, lower mortality rates while ignoring the historical burden of vaccine-preventable diseases. The evidence shows that thousands of deaths occurred from vaccine-preventable infections before widespread vaccination ^[3], contradicting any suggestion that mortality was naturally low.

Cherry-picking temporal data represents another potential bias. The question may reflect selective attention to periods when mortality appeared lower while ignoring the broader historical context showing >99% decline in mortality for many diseases after vaccine implementation ^[1].

The framing also lacks acknowledgment of ongoing vaccine effectiveness, as demonstrated by studies showing no increased risk of non-COVID-19 mortality after vaccination ^[9] and clear evidence of mortality reduction during high-vaccination periods ^[7]. This suggests the question may be promoting a predetermined conclusion rather than seeking objective information about historical mortality patterns.