# Vaccine & Immunization Tracker vs FourthTri

The clearest difference is iOS requirement: Vaccine & Immunization Tracker at 15.5 against FourthTri's 18.0. On price, update cadence, ads and in-app purchases there is nothing between them.

Both are free to download. Vaccine & Immunization Tracker sells 1 one-off in-app purchase and FourthTri sells 1 one-off in-app purchase. Whichever you choose, the download price is not the number that matters.

Vaccine & Immunization Tracker ships an update every 2 weeks, FourthTri every 11 days. The most recent releases landed on October 6, 2026 and October 16, 2026 respectively.

## The numbers

| Metric | Vaccine & Immunization Tracker | FourthTri |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | Yes | Yes |
| Ads | No | No |
| Update frequency | Every 2 weeks | **Every 11 days** |
| Size | 78 MB | 6 MB |
| Requires iOS | **15.5** | 18.0 |
| Devices | iPhone, iPod | **iPhone, iPad, Apple Watch** |
| Age rating | 4+ | 4+ |
| Developer | [Varsha Sharma](https://appshunter.io/developer/6776509160) | [InnovaLabWorks](https://appshunter.io/developer/1888514726) |

## What reviewers say

### Vaccine & Immunization Tracker

[App page](https://appshunter.io/ios/app/vaccine-and-immunization-tracker/id6776509158)

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Premium Unlock | $9.99 | one-time |


### FourthTri

[App page](https://appshunter.io/ios/app/fourthtri-postpartum/id6792523331)

**Features:** macOS Compatibility, Apple Watch app, Vision Pro support

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Lifetime Unlock | $49.99 | one-time |


## Frequently asked questions

### Is Vaccine & Immunization Tracker free?

Vaccine & Immunization Tracker is free to download, with in-app purchases available.

### Is FourthTri free?

FourthTri is free to download, with in-app purchases available.

### Do Vaccine & Immunization Tracker or FourthTri have ads?

Neither Vaccine & Immunization Tracker nor FourthTri shows ads.

### Which is updated more often, Vaccine & Immunization Tracker or FourthTri?

Vaccine & Immunization Tracker ships an update every 2 weeks, and FourthTri every 11 days. Most recently, Vaccine & Immunization Tracker was updated on October 6, 2026 and FourthTri on October 16, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*