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 Desktop Performance
72/100
These metrics represent real-world Chrome users experience viewing cdc.gov web page. 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
Largest Contentful Paint
Cumulative Layout Shift
First Input Delay
First Contentful Paint
Metrics
Largest Contentful Paint33/100 3.1 s
Largest Contentful Paint marks the time at which the largest text or image is painted. Learn More
Cumulative Layout Shift53/100 0.237
Cumulative Layout Shift measures the movement of visible elements within the viewport. Learn more.
First Contentful Paint73/100 1.2 s
First Contentful Paint marks the time at which the first text or image is painted. Learn more.
Speed Index78/100 1.6 s
Speed Index shows how quickly the contents of a page are visibly populated. Learn more.
Time to Interactive87/100 2.7 s
Time to interactive is the amount of time it takes for the page to become fully interactive. Learn more.
Total Blocking Time100/100 10 ms
Sum of all time periods between FCP and Time to Interactive, when task length exceeded 50ms, expressed in milliseconds. Learn more.
Should Fix (15)
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
480 ms
Efficiently encode images
Potential savings of 477 KiB
400 ms
Properly size images
Potential savings of 463 KiB
400 ms
Avoid multiple page redirects
Potential savings of 340 ms
340 ms
Remove unused CSS
Potential savings of 88 KiB
160 ms
Eliminate render-blocking resources
Potential savings of 160 ms
159 ms
Remove unused JavaScript
Potential savings of 57 KiB
80 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
Largest Contentful Paint element
1 element found
Avoid chaining critical requests
13 chains found
Avoid large layout shifts
5 elements found
Avoid long main-thread tasks
4 long tasks found
Keep request counts low and transfer sizes small
49 requests • 1,900 KiB
Passed Audits (14)
Minimize third-party usage
Third-party code blocked the main thread for 0 ms
Avoids `document.write()`
Use video formats for animated content
Preload key requests
Initial server response time was short
Root document took 220 ms
Minimizes main-thread work
0.9 s
Minify JavaScript
Preconnect to required origins
JavaScript execution time
0.3 s
Uses passive listeners to improve scrolling performance
Enable text compression
Minify CSS
Defer offscreen images
Avoids enormous network payloads
Total size was 1,900 KiB
cdc.gov Desktop 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 (1)
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 (11)
Has a `<meta name="viewport">` tag with `width` or `initial-scale`
Document has a meta description
Image elements have `[alt]` attributes
Document has a `<title>` element
Page has successful HTTP status code
Document has a valid `hreflang`
Page isn’t blocked from indexing
Document has a valid `rel=canonical`
Document avoids plugins
Links are crawlable
robots.txt is valid
cdc.gov Desktop Best Practices
85/100
These checks highlight opportunities to improve the overall code health of cdc.gov 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)
Avoids requesting the notification permission on page load
Avoids requesting the geolocation permission on page load
Detected JavaScript libraries
No browser errors logged to the console
Serves images with appropriate resolution
Properly defines charset
Avoids front-end JavaScript libraries with known security vulnerabilities
Allows users to paste into password fields
Avoids Application Cache
Displays images with correct aspect ratio
Avoids deprecated APIs
Page has the HTML doctype
cdc.gov Desktop Progressive Web App
19/100
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 set a theme color for the address bar.
Manifest doesn't have a maskable icon
Does not provide a valid `apple-touch-icon`
Is not configured for a custom splash screen
Fast and reliable
Current page does not respond with a 200 when offline
Page load is not fast enough on mobile networks
Interactive on simulated mobile network at 11.9 s
`start_url` 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 (3)
Has a `<meta name="viewport">` tag with `width` or `initial-scale`
Contains some content when JavaScript is not available
Redirects HTTP traffic to HTTPS
cdc.gov Desktop Accessibility
100/100
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.
Passed Audits (23)
The page contains a heading, skip link, or landmark region
`[role]`s have all required `[aria-*]` attributes
Elements with an ARIA `[role]` that require children to contain a specific `[role]` have all required children.
Lists contain only `<li>` elements and script supporting elements (`<script>` and `<template>`).
Links have a discernible name
List items (`<li>`) are contained within `<ul>` or `<ol>` parent elements
Image elements have `[alt]` attributes
Document has a `<title>` element
`[id]` attributes on active, focusable elements are unique
`[aria-*]` attributes match their roles
`[role]` values are valid
ARIA IDs are unique
`[aria-*]` attributes have valid values
Buttons have an accessible name
`[aria-*]` attributes are valid and not misspelled
`<html>` element has a `[lang]` attribute
Background and foreground colors have a sufficient contrast ratio
`<html>` element has a valid value for its `[lang]` attribute
`[role]`s are contained by their required parent element
`[aria-hidden="true"]` is not present on the document `<body>`
Form elements have associated labels
`[user-scalable="no"]` is not used in the `<meta name="viewport">` element and the `[maximum-scale]` attribute is not less than 5.
`[aria-hidden="true"]` elements do not contain focusable descendents
Desktop Speed
54/100
These checks analyze the performance of cdc.gov on desktop devices and return PageSpeed score and information on how to improve the load time. What makes a good Progressive Web App?
Should Fix (7)
Optimize images
Leverage browser caching
Eliminate render-blocking JavaScript and CSS in above-the-fold content
Minify JavaScript
Minify HTML
Minify CSS
Enable compression
Passed Audits (3)
Avoid landing page redirects
Reduce server response time
Prioritize visible content
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