# STI Tx Guide vs CDC Yellow Book

The clearest difference is rating: CDC Yellow Book at 4.2 against STI Tx Guide's 3.5. STI Tx Guide's advantage is in-app purchases (none vs 2) and update cadence (every 2 months vs every 21 months). On price, ratings volume, ads and device support there is nothing between them.

Both are free to download. CDC Yellow Book sells 1 one-off in-app purchase. STI Tx Guide asks for nothing beyond the download.

CDC Yellow Book holds the better App Store score, 4.2 against 3.5. Both are backed by a comparable volume of ratings — 36 and 69 respectively. Written reviews complicate that: 36% of STI Tx Guide's written reviews are positive against 20% of CDC Yellow Book's, so the app with the better star average is not the one people write more warmly about.

STI Tx Guide ships an update every 2 months, CDC Yellow Book every 21 months. The most recent releases landed on October 23, 2026 and October 24, 2026 respectively.

## The numbers

| Metric | STI Tx Guide | CDC Yellow Book |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [3.5 (36 ratings)](https://appshunter.io/ios/app/sti-tx-guide/id655206856/reviews) | **[4.2 (69 ratings)](https://appshunter.io/ios/app/cdc-yellow-book/id1235766820/reviews)** |
| Number of ratings | 36 | **69** |
| Positive reviews | **35.7% of reviews** | 20.0% of reviews |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | **Every 2 months** | Every 21 months |
| Monetization | **Free** | Free with in-app purchases |
| Size | 36 MB | 10 MB |
| Requires iOS | 15.0 | 15.0 |
| Devices | iPhone, iPod | **iPhone, iPad, iPod** |
| Age rating | 12+ | 17+ |
| Developer | [Centers For Disease Control and Prevention](https://appshunter.io/developer/439259253) | [Unbound Medicine, Inc.](https://appshunter.io/developer/300420400) |

## What reviewers say

### STI Tx Guide

[App page](https://appshunter.io/ios/app/sti-tx-guide/id655206856)

Provides healthcare professionals with up-to-date, evidence-based recommendations for the prevention, diagnosis, and treatment of sexually transmitted infections. Features include clinical care guidance, sexual history resources, and patient materials for effective patient management.

**Highlights:** STI prevention recommendations, Diagnosis guidance, Treatment protocols, Clinical care assistance, Sexual history resources, Patient management tools

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

**In-app purchases:** none


### CDC Yellow Book

[App page](https://appshunter.io/ios/app/cdc-yellow-book/id1235766820)

Access the U.S. government's most current travel health guidelines, including vaccine recommendations and destination-specific advice. This app offers comprehensive information for staying healthy abroad, with features like search, notes, and favorites.

**Highlights:** Pre-travel vaccinations and preventative care, Destination-specific guidelines, Advice for travelers with specific health needs, Full text search, Custom notes and highlights, Reference maps, tables, and charts

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

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| CDC Yellow Book | $29.99 | one-time |


## Frequently asked questions

### Is STI Tx Guide free?

STI Tx Guide is free to download, with no in-app purchases.

### Is CDC Yellow Book free?

CDC Yellow Book is free to download, with in-app purchases available.

### Which has better reviews, STI Tx Guide or CDC Yellow Book?

CDC Yellow Book is rated higher. STI Tx Guide averages 3.5 out of 5 from 36 ratings, while CDC Yellow Book averages 4.2 from 69 ratings.

### Do STI Tx Guide or CDC Yellow Book have ads?

Neither STI Tx Guide nor CDC Yellow Book shows ads.

### Which is updated more often, STI Tx Guide or CDC Yellow Book?

STI Tx Guide ships an update every 2 months, and CDC Yellow Book every 21 months. Most recently, STI Tx Guide was updated on October 23, 2026 and CDC Yellow Book on October 24, 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.*