Twitter and Instagram are attempting to crack down on the spread of anti-vaccine propaganda on their platforms.

Social networks have come under sustained criticism for serving as platforms for a variety of anti-vaxx myths, and helping spread misinformation.

In an attempt to deal with such posts, Instagram and Twitter have both taken steps to try and dissuade people from reading them.

Twitter appears to have introduced a new tool that means anyone searching for terms associated with anti-vaccine stories will instead see a link out to the NHS, which is running a page attempting to address the myths spread by anti-vaccine users.

At least some users appear to be shown a special page that blocks out the traditionl search results and instead encourages them to read the official NHS website.

Gadget and tech news: In pictures Show all 25 1 /25 Gadget and tech news: In pictures Gadget and tech news: In pictures Gun-toting humanoid robot sent into space Russia has launched a humanoid robot into space on a rocket bound for the International Space Station (ISS). The robot Fedor will spend 10 days aboard the ISS practising skills such as using tools to fix issues onboard. Russia's deputy prime minister Dmitry Rogozin has previously shared videos of Fedor handling and shooting guns at a firing range with deadly accuracy. Dmitry Rogozin/Twitter Gadget and tech news: In pictures Google turns 21 Google celebrates its 21st birthday on September 27. The The search engine was founded in September 1998 by two PhD students, Larry Page and Sergey Brin, in their dormitories at California’s Stanford University. Page and Brin chose the name google as it recalled the mathematic term 'googol', meaning 10 raised to the power of 100 Google Gadget and tech news: In pictures Hexa drone lifts off Chief engineer of LIFT aircraft Balazs Kerulo demonstrates the company's "Hexa" personal drone craft in Lago Vista, Texas on June 3 2019 Reuters Gadget and tech news: In pictures Project Scarlett to succeed Xbox One Microsoft announced Project Scarlett, the successor to the Xbox One, at E3 2019. The company said that the new console will be 4 times as powerful as the Xbox One and is slated for a release date of Christmas 2020 Getty Gadget and tech news: In pictures First new iPod in four years Apple has announced the new iPod Touch, the first new iPod in four years. The device will have the option of adding more storage, up to 256GB Apple Gadget and tech news: In pictures Folding phone may flop Samsung will cancel orders of its Galaxy Fold phone at the end of May if the phone is not then ready for sale. The $2000 folding phone has been found to break easily with review copies being recalled after backlash PA Gadget and tech news: In pictures Charging mat non-starter Apple has cancelled its AirPower wireless charging mat, which was slated as a way to charge numerous apple products at once AFP/Getty Gadget and tech news: In pictures "Super league" India shoots down satellite India has claimed status as part of a "super league" of nations after shooting down a live satellite in a test of new missile technology EPA Gadget and tech news: In pictures 5G incoming 5G wireless internet is expected to launch in 2019, with the potential to reach speeds of 50mb/s Getty Gadget and tech news: In pictures Uber halts driverless testing after death Uber has halted testing of driverless vehicles after a woman was killed by one of their cars in Tempe, Arizona. March 19 2018 Getty Gadget and tech news: In pictures A humanoid robot gestures during a demo at a stall in the Indian Machine Tools Expo, IMTEX/Tooltech 2017 held in Bangalore Getty Gadget and tech news: In pictures A humanoid robot gestures during a demo at a stall in the Indian Machine Tools Expo, IMTEX/Tooltech 2017 held in Bangalore Getty Gadget and tech news: In pictures Engineers test a four-metre-tall humanoid manned robot dubbed Method-2 in a lab of the Hankook Mirae Technology in Gunpo, south of Seoul, South Korea Jung Yeon-Je/AFP/Getty Gadget and tech news: In pictures Engineers test a four-metre-tall humanoid manned robot dubbed Method-2 in a lab of the Hankook Mirae Technology in Gunpo, south of Seoul, South Korea Jung Yeon-Je/AFP/Getty Gadget and tech news: In pictures The giant human-like robot bears a striking resemblance to the military robots starring in the movie 'Avatar' and is claimed as a world first by its creators from a South Korean robotic company Jung Yeon-Je/AFP/Getty Gadget and tech news: In pictures Engineers test a four-metre-tall humanoid manned robot dubbed Method-2 in a lab of the Hankook Mirae Technology in Gunpo, south of Seoul, South Korea Jung Yeon-Je/AFP/Getty Gadget and tech news: In pictures Waseda University's saxophonist robot WAS-5, developed by professor Atsuo Takanishi Rex Gadget and tech news: In pictures Waseda University's saxophonist robot WAS-5, developed by professor Atsuo Takanishi and Kaptain Rock playing one string light saber guitar perform jam session Rex Gadget and tech news: In pictures A test line of a new energy suspension railway resembling the giant panda is seen in Chengdu, Sichuan Province, China Reuters Gadget and tech news: In pictures A test line of a new energy suspension railway, resembling a giant panda, is seen in Chengdu, Sichuan Province, China Reuters Gadget and tech news: In pictures A concept car by Trumpchi from GAC Group is shown at the International Automobile Exhibition in Guangzhou, China Rex Gadget and tech news: In pictures A Mirai fuel cell vehicle by Toyota is displayed at the International Automobile Exhibition in Guangzhou, China Reuters Gadget and tech news: In pictures A visitor tries a Nissan VR experience at the International Automobile Exhibition in Guangzhou, China Reuters Gadget and tech news: In pictures A man looks at an exhibit entitled 'Mimus' a giant industrial robot which has been reprogrammed to interact with humans during a photocall at the new Design Museum in South Kensington, London Getty Gadget and tech news: In pictures A new Israeli Da-Vinci unmanned aerial vehicle manufactured by Elbit Systems is displayed during the 4th International conference on Home Land Security and Cyber in the Israeli coastal city of Tel Aviv Getty

Twitter does not otherwise appear to be changing what shows in search results. At the time of publication, the first results shown under the NHS post when searching for "vaccine" in Twitter was from someone spreading anti-vaccine stories.

Instagram is also cracking down on misinformation about vaccinations being spread across the photo sharing app by blocking hashtags that draw out "verifiably false" posts about the controversial subject.

Inaccurate and misleading anti-vaccination messages on social media are thought to be one of the reasons why vaccination rates have dropped in recent years, with an estimated 169 million children around the world missing out on the first dose of the measles vaccine between 2010 and 2017, according to recent numbers from charity Unicef.

The Facebook-owned platform already blocks obvious hashtag terms used to spread false information, such as #vaccinescauseautism, #vaccinescauseaids and #vaccinesarepoison, but its policy is now being extended to address vaccine hashtags that seem innocent on the surface.

For example, a hashtag like #vaccines1234 does not contain anything alarming in its wording, but if it is found to be used in a number of posts to promote verifiably false vaccine misinformation it will be added to the block list.

When a hashtag is blocked, users are presented with no results when searching it on the social network.

However, Instagram's approach continues to only targets misinformation about vaccines and not anti-vax opinions, which it says is not something it would take action on.

Instagram did not specify a limit on the number of times a hashtag is being abused before blocking it, stating that it will block hashtags whereby the content surfaced on the hashtag page contains a "certain amount" of verifiably false vaccine misinformation.

The move comes after Facebook said it was "exploring additional measures" to address anti-vaccination posts in February, following concerns raised about the controversial subject appearing in groups and pages across Facebook.

At the time, the company admitted that the task is challenging as it grapples with striking a balance between freedom to express opinion and the safety of its users, but said it was committed to tackling the problem.

Last month, Health Secretary Matt Hancock said he "wouldn't rule out anything" when asked whether unvaccinated children should be banned from schools.

NHS England chief executive Simon Stevens has also described vaccine refusal as a "growing public health timebomb".