Why Early COVID-19 Vaccine Effectiveness Was Overestimated

The problem with average VE goes well beyond 14 day asymmetrical case counting windows. Over a third of patients hospitalized with COVID-19 were not treated for COVID-19 and that includes more than half of pediatric patients who tested positive with COVID-19 during their hospitalization. An investigation of hospital admissions that included a positive COVID-19 test between March 1, 2020 and January 31, 2022 (n = 814,672) revealed that about 20–40% of patients hospitalized with COVID-19 were admitted for other causes and tested positive for a mild or asymptomatic COVID-19 case after admission including 36% between November 2021 and January 2022. Only 38% of pediatric patients who were hospitalized with COVID-19 during this time were admitted due to COVID-19 as the primary cause or a cause in conjunction with other problems. That means 62% of pediatric COVID-19 hospitalizations were incidental i.e. that were hospitalized for other reasons and tested positive after admission. Generally, the higher up you go in the age distribution the more likely that hospitalized with COVID-19 meant hospitalized for COVID-19 but that was not the case for patients under 18 years most of the time. Most observational research estimating VE against hospitalization did not make this distinction especially when the shots were rolled out to kids in late 2021.

A retrospective case series, conducted within a tertiary care children’s hospital between May and September 2020 (n = 163) found that most pediatric patients admitted with a positive SARS-CoV-2 test result found that most patients were either incidentally infected without symptoms (58/163) or potentially symptomatic (68/163) neither of which ‘required no interventions related to their COVID-19 diagnosis during their hospitalization (77.3%)’ and only 11% of potentially symptomatic patients were admitted for a positive SARS-COV-2 test result. Furthermore, 90% of significantly symptomatic patients (37/163) had one or more comorbidities including obesity (60%) and asthma (35%) and only 1 of the 4 deaths with COVID-19 was attributable to COVID-19.

A retrospective cohort study, conducted at a university-based, quaternary care children’s hospital in Northern California between May 2020 and February 2021 (n = 117) found that most pediatric patients hospitalized with COVID-19 were either asymptomatic (39.3%) or had mild to moderate COVID-19 symptoms (28.2%) while roughly a third had either severe illness, critical illness requiring respiratory support or multiple inflammatory syndrome in children and nearly half of infections were no a cause of hospitalization itself. The hysteria around COVID-19 likely lead parents to believe their children disease progression would be worse than it actually was and thus they brought their children to the hospital as soon as they tested positive despite having mild or no symptoms of the virus at all.

Conflating hospitalization WITH COVID-19 and FOR COVID-19 is not the only specious assumption officials made in VE against hospitalization estimates. As Bourdon and colleagues note in their re-analysis of the FDA benefit-risk assessment of Moderna’s modRNA transfection for 18-25 year old males, the agency made several false assumptions in their model, did not consider protection conferred by prior infection against hospitalization and re-infection and only accounted for hospitalization for one SAE (e.g. cardiomyopathy) and only from the second dose of the primary series. The FDA model assumed all unvaxxed males would be infected within a 5 month time frame, assumed the Moderna modRNA transfection resulted in the same rate of myo/pericarditis as Pfizer’s (in fact it was 2x as frequent for the Moderna shots), used confirmed cases, which is a fraction of the infection rate, to estimate the COVID-19 hospitalization rate for everyone 18-45 years old which they also assumed was the same for everyone in that age range, and did not separate incidental COVID-19 hospitalizations, in which a patient is admitted for another cause and tests positive for the virus after admission, and hospitalization due to COVID-19. A re-analysis using age stratified data for COVID-19 hospitalizations, age stratified and brand specific data for vaxx induced myo/pericarditis and including protection conferred by natural immunity estimated 16% and 63% more hospitalizations from vaccine-attributable myo/pericarditis than hospitalizations for COVID-19 in the 18–25 year old age range.