ForHosting KIT · Developer Utilities

Vaccine immunity calculator

Vaccine-induced protection is not a constant. Published vaccine efficacy describes peak protection around the time a primary series is completed; each additional month after the last dose lets that protection wane along a smooth exponential curve, and an incomplete series never reaches the published peak.

● BetaFree · in your browser

Run — free How it works & API

Use it from WebAPIEmailTelegramApp soon

This vaccine immunity calculator estimates remaining protection as a percentage from three numbers: efficacy between zero and one hundred, the count of doses received, and months elapsed since the last dose. It applies a fixed educational waning rate with a twelve-month half-life and a two-dose saturating series factor, then returns the remaining percentage together with the peak, the dose factor, and the waning factor so every step can be audited. The free browser tool and the API share the same pure JavaScript library, so interactive checks and automated tasks always agree. No network lookup, no randomness, and no dependence on the current date—only arithmetic on the numbers you provide. Treat every result as an educational estimate of remaining vaccine-induced protection, never as a clinical titre, a booster recommendation, or a substitute for a clinician.

How to use it

Enter your values in the form above. The tool checks them before calculating and shows the result on the same page.

Check your inputs

Use the labels and units shown next to each field. If something is missing or outside the allowed range, the page points to the field to fix.

Use it again or automate it

Use the browser tool for individual checks and the API when you need the same capability in an automated workflow.

What you can do with it

Get an answer now

Enter one set of values and see the result without building a spreadsheet or script.

Compare scenarios

Change one value at a time and rerun the calculation to understand what affects the result.

Automate repeated work

Use the API when the same calculation needs to run inside your product or workflow.

FAQ

What formula does the vaccine immunity calculator use?

remaining_percent = efficacy × min(1, doses/2) × exp(−ln(2)×months/12). Peak protection is published efficacy scaled by a two-dose saturating series; waning uses a fixed twelve-month half-life.

Why does efficacy outside 0-100 fail?

Vaccine efficacy is a percentage. Values below 0 or above 100 are not a valid efficacy, so the task fails with invalid_input and is not billed.

How do extra doses after a two-dose series affect the estimate?

Doses at or above two saturate the peak at published efficacy. Extra doses do not raise remaining_percent above that peak; they only matter through the months-since-last-dose clock you supply.

Does remaining_percent equal a lab titre or a booster recommendation?

No. The result is an educational percentage from a fixed-waning formula. It is not a neutralizing-antibody titre, a diagnosis, or advice to take a booster.

Is the vaccine immunity calculator free?

The browser tool is free. API calls cost $0.002 per successful request from your prepaid KIT balance; failed validation is never charged.

For developers — API access

Everything on this page is available programmatically. This section is for teams who want to wire it into their own systems; everyone else can just use the tool above.

API endpoint

POSThttps://api.kit.forhosting.com/health/vaccine-immunity

Prefer to automate it? One authenticated POST creates the task; the result comes back by webhook or a signed link. The same capability also runs here on the web, by email and from Telegram — and soon from our app too.

Call it from your stack

curl -X POST https://api.kit.forhosting.com/health/vaccine-immunity \
  -H "Authorization: Bearer $KIT_KEY" \
  -H "Content-Type: application/json" \
  -d '{"efficacy":95,"doses":2,"months":6}'

const res = await fetch("https://api.kit.forhosting.com/health/vaccine-immunity", {
  method: "POST",
  headers: {
    "Authorization": `Bearer ${process.env.KIT_KEY}`,
    "Content-Type": "application/json"
  },
  body: JSON.stringify({
    "efficacy": 95,
    "doses": 2,
    "months": 6
  })
});
const { task_id } = await res.json();

import os, requests

res = requests.post(
    "https://api.kit.forhosting.com/health/vaccine-immunity",
    headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
    json={
    "efficacy": 95,
    "doses": 2,
    "months": 6
},
)
task_id = res.json()["task_id"]

<?php
$res = file_get_contents("https://api.kit.forhosting.com/health/vaccine-immunity", false, stream_context_create([
  "http" => [
    "method"  => "POST",
    "header"  => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
    "content" => '{"efficacy":95,"doses":2,"months":6}',
  ],
]));
$task = json_decode($res, true);

body := bytes.NewBufferString(`{"efficacy":95,"doses":2,"months":6}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/health/vaccine-immunity", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)

Example request

{
  "efficacy": 95,
  "doses": 2,
  "months": 6
}

Example response

{
  "task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
  "type": "health.vaccine_immunity",
  "status": "queued",
  "_links": {
    "result": "/tasks/tsk_…/result"
  }
}

The API is asynchronous: the call returns a task_id immediately and the result arrives by webhook. Polling is capped at 1 req/s per task.

Pricing

Per request$0.002

Published price — no tokens, no invented credits. A failed task is never charged.

Limits

`max_doses`	20
`max_months`	600

Errors

HTTP	Code	Meaning
`401`	`unauthorized`	Missing or invalid API key.
`402`	`insufficient_balance`	Your balance doesn't cover the task price.
`404`	`unknown_type`	That task type doesn't exist.
`429`	`rate_limited`	Too many requests. Use the webhook instead of polling.

Read the full KIT documentation →