Cdc.gov Centers for Disease Control and Prevention
As the nation’s health protection agency, CDC saves lives and protects people from health, safety, and security threats.
cdc.gov Mobile Performance
39/100
These metrics represent real-world Chrome users experience viewing cdc.gov on mobile devices. Reports are focused on loading performance and other critical factors that most affect user experience. Follow our guide to track, optimize, and improve the quality of your web pages.
User Loading Experience
First Input Delay
First Contentful Paint
Cumulative Layout Shift
Largest Contentful Paint
Metrics
Largest Contentful Paint0/100 13.1 s
Largest Contentful Paint marks the time at which the largest text or image is painted. Learn More
Time to Interactive17/100 11.9 s
Time to interactive is the amount of time it takes for the page to become fully interactive. Learn more.
First Contentful Paint35/100 4.7 s
First Contentful Paint marks the time at which the first text or image is painted. Learn more.
Speed Index42/100 6.3 s
Speed Index shows how quickly the contents of a page are visibly populated. Learn more.
Total Blocking Time81/100 360 ms
Sum of all time periods between FCP and Time to Interactive, when task length exceeded 50ms, expressed in milliseconds. Learn more.
Cumulative Layout Shift100/100 0
Cumulative Layout Shift measures the movement of visible elements within the viewport. Learn more.
Should Fix (17)
Opportunities
These suggestions can help your page load faster. They don't directly affect the Performance score.
Serve images in next-gen formats
Potential savings of 672 KiB
3,450 ms
Efficiently encode images
Potential savings of 477 KiB
2,700 ms
Defer offscreen images
Potential savings of 463 KiB
1,650 ms
Avoid multiple page redirects
Potential savings of 1,110 ms
1,110 ms
Remove unused CSS
Potential savings of 88 KiB
960 ms
Properly size images
Potential savings of 137 KiB
900 ms
Remove unused JavaScript
Potential savings of 57 KiB
450 ms
Eliminate render-blocking resources
Potential savings of 410 ms
412 ms
Diagnostics
More information about the performance of your application. These numbers don't directly affect the Performance score.
Ensure text remains visible during webfont load
Serve static assets with an efficient cache policy
35 resources found
Avoid an excessive DOM size
1,127 elements
Minimize main-thread work
2.9 s
Reduce JavaScript execution time
1.4 s
Avoid chaining critical requests
13 chains found
Avoid long main-thread tasks
14 long tasks found
Keep request counts low and transfer sizes small
51 requests • 1,902 KiB
Largest Contentful Paint element
1 element found
Passed Audits (11)
Initial server response time was short
Root document took 90 ms
Avoids enormous network payloads
Total size was 1,902 KiB
Avoids `document.write()`
Minimize third-party usage
Third-party code blocked the main thread for 30 ms
Uses passive listeners to improve scrolling performance
Enable text compression
Preload key requests
Minify JavaScript
Preconnect to required origins
Minify CSS
Use video formats for animated content
cdc.gov Mobile SEO
92/100
These checks ensure that your page is optimized for search engine results ranking. There are additional factors Lighthouse does not check that may affect your search ranking. Learn more. Run these additional validators on your site to check additional SEO best practices.
Should Fix (2)
Mobile Friendly
Make sure your pages are mobile friendly so users don’t have to pinch or zoom in order to read the content pages. Learn more.
Tap targets are not sized appropriately
91% appropriately sized tap targets
Content Best Practices
Format your HTML in a way that enables crawlers to better understand your app’s content.
Links do not have descriptive text
4 links found
Passed Audits (12)
Has a `<meta name="viewport">` tag with `width` or `initial-scale`
Document has a valid `rel=canonical`
Page has successful HTTP status code
Document avoids plugins
Document has a `<title>` element
Document uses legible font sizes
100% legible text
robots.txt is valid
Document has a meta description
Document has a valid `hreflang`
Image elements have `[alt]` attributes
Page isn’t blocked from indexing
Links are crawlable
cdc.gov Mobile Best Practices
85/100
These checks highlight opportunities to improve the overall code health of cdc.gov mobile page. Current recommendations will help to make your page fast and secure, to create a good user experience and to avoid deprecated technologies.
Should Fix (2)
Trust and Safety
Links to cross-origin destinations are unsafe
Does not use HTTPS
1 insecure request found
Passed Audits (12)
No browser errors logged to the console
Allows users to paste into password fields
Avoids requesting the notification permission on page load
Avoids Application Cache
Avoids requesting the geolocation permission on page load
Page has the HTML doctype
Detected JavaScript libraries
Avoids deprecated APIs
Avoids front-end JavaScript libraries with known security vulnerabilities
Serves images with appropriate resolution
Properly defines charset
Displays images with correct aspect ratio
cdc.gov Mobile Progressive Web App
21/100
These checks validate the aspects of a Progressive Web App. Learn more. These checks are required by the baseline PWA Checklist but are not automatically checked by Lighthouse. They do not affect your score but it's important that you verify them manually.
Should Fix (10)
PWA Optimized
Does not provide a valid `apple-touch-icon`
Does not set a theme color for the address bar.
Manifest doesn't have a maskable icon
Is not configured for a custom splash screen
Fast and reliable
Page load is not fast enough on mobile networks
Interactive at 11.9 s
`start_url` does not respond with a 200 when offline
Current page does not respond with a 200 when offline
Installable
Does not use HTTPS
1 insecure request found
Does not register a service worker that controls page and `start_url`
Web app manifest does not meet the installability requirements
Passed Audits (4)
Has a `<meta name="viewport">` tag with `width` or `initial-scale`
Content is sized correctly for the viewport
Contains some content when JavaScript is not available
Redirects HTTP traffic to HTTPS
cdc.gov Mobile Accessibility
93/100
These checks highlight opportunities to improve the accessibility of your web app. Only a subset of accessibility issues can be automatically detected so manual testing is also encouraged. These items address areas which an automated testing tool cannot cover. Learn more in our guide on conducting an accessibility review.
Should Fix (1)
Names and labels
These are opportunities to improve the semantics of the controls in your application. This may enhance the experience for users of assistive technology, like a screen reader.
Buttons do not have an accessible name
Passed Audits (20)
`[aria-hidden="true"]` is not present on the document `<body>`
`<html>` element has a `[lang]` attribute
Background and foreground colors have a sufficient contrast ratio
`[aria-hidden="true"]` elements do not contain focusable descendents
The page contains a heading, skip link, or landmark region
Document has a `<title>` element
`[aria-*]` attributes match their roles
Links have a discernible name
`[role]`s have all required `[aria-*]` attributes
List items (`<li>`) are contained within `<ul>` or `<ol>` parent elements
ARIA IDs are unique
`[role]`s are contained by their required parent element
`[role]` values are valid
Lists contain only `<li>` elements and script supporting elements (`<script>` and `<template>`).
Elements with an ARIA `[role]` that require children to contain a specific `[role]` have all required children.
`[aria-*]` attributes have valid values
`[aria-*]` attributes are valid and not misspelled
Image elements have `[alt]` attributes
`[user-scalable="no"]` is not used in the `<meta name="viewport">` element and the `[maximum-scale]` attribute is not less than 5.
`<html>` element has a valid value for its `[lang]` attribute
Mobile Usability
99/100
These checks validate how easily a visitor can use cdc.gov on a mobile device. Test results include a list of any mobile usability problems. Mobile usability problems are issues that can affect a user that visits the page on a mobile (small screen) device, including small font sizes (which are hard to read on a small screen).
Should Fix (1)
Size tap targets appropriately
Passed Audits (4)
Avoid plugins
Configure the viewport
Size content to viewport
Use legible font sizes
Mobile Speed
58/100
These checks analyze the performance of cdc.gov on mobile devices and return PageSpeed score and information on how to improve the load time. What makes a good Progressive Web App?
Should Fix (6)
Leverage browser caching
Optimize images
Eliminate render-blocking JavaScript and CSS in above-the-fold content
Minify JavaScript
Minify HTML
Minify CSS
Passed Audits (4)
Avoid landing page redirects
Enable compression
Reduce server response time
Prioritize visible content
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