Include confirmed cases and estimated undiagnosed cases.
Calculated IFR
0.00%
This means approximately 0 out of every 1,000 infected individuals die from the disease.
Understanding Infection Fatality Rate (IFR)
The Infection Fatality Rate (IFR) is a critical epidemiological metric used to estimate the proportion of deaths among all infected individuals, including those with symptoms and those who are asymptomatic or undiagnosed. Unlike the Case Fatality Rate (CFR), which only counts confirmed cases, the IFR attempts to account for the total burden of infection in a population.
The Formula
The calculation for IFR is straightforward mathematically but requires accurate data estimation:
It is important to distinguish between IFR and CFR:
CFR (Case Fatality Rate): Calculates deaths based only on confirmed medical cases. It often overestimates the fatality risk because mild cases are not tested.
IFR (Infection Fatality Rate): Calculates deaths based on all infections. This is generally lower than CFR and provides a more accurate picture of the virus's lethality across the general population.
Why IFR Matters
Public health officials use IFR to model the potential impact of a disease on a population. Knowing the IFR helps in:
Estimating the total number of deaths if herd immunity is reached.
Determining the cost-benefit analysis of lockdowns and social distancing measures.
Allocating healthcare resources effectively.
Frequently Asked Questions
How is the total number of infections estimated?
Total infections are usually estimated using seroprevalence studies (antibody tests) to detect past infections in a random sample of the population. Statistical modeling is then applied to extrapolate these findings to the broader population.
Why does IFR change over time?
IFR is not a biological constant. It varies based on the age demographics of the infected population, the capacity of the healthcare system, the availability of treatments, and the underlying health of the population (comorbidities).
Is a lower IFR always better?
While a lower percentage is individually better, a virus with a low IFR but extremely high transmissibility (R0) can still cause a massive number of deaths simply by infecting a very large portion of the population.
function validateInputs() {
var deaths = document.getElementById('totalDeaths').value;
var infections = document.getElementById('totalInfections').value;
var errorDiv = document.getElementById('errorMsg');
// Basic realtime cleanup if needed, but mostly logic happens on click
if (deaths < 0) document.getElementById('totalDeaths').value = 0;
if (infections infections) {
errorDiv.innerHTML = "Number of deaths cannot exceed total infections.";
errorDiv.style.display = "block";
resultBox.style.display = "none";
return;
}
// Calculation
var ifr = (deaths / infections) * 100;
var perThousand = (deaths / infections) * 1000;
// Formatting results (Max 4 decimal places for precision on small percentages)
var formattedIFR = ifr.toFixed(4);
// If the number is very small but not zero, show scientific notation or more decimals?
// Let's stick to standard readable format. If it's basically 0, show 0 && ifr < 0.0001) {
formattedIFR = "< 0.0001";
} else {
// Remove trailing zeros if they are just extra
formattedIFR = parseFloat(formattedIFR).toString();
}
var formattedPerThousand = perThousand.toFixed(2);
formattedPerThousand = parseFloat(formattedPerThousand).toString();
// Update DOM
ifrValueDisplay.innerHTML = formattedIFR + "%";
perThousandDisplay.innerHTML = formattedPerThousand;
errorDiv.style.display = "none";
resultBox.style.display = "block";
}