The UK will ban children under 16 from social media by early next year, replicating a policy that came into effect in Australia in 2025. The move is intended to put children鈥檚 well-being ahead of technology companies鈥� profits. But how will scientists study the effects of the measure and determine whether it is actually having a positive impact?

鈥淲e have no evidence either way,鈥� says at Bath Spa University in the UK, who is working with the Australian government to analyse the effects of its own ban and is also advising the UK government. 鈥淚t鈥檚 such new territory.鈥�

Leading the way on research in the UK is the Wellcome Trust, which is already deep into the IRL Trial in Bradford. This has recruited about 4000 kids from 10 schools, aged 12 to 15, who installed an app on their phones to track their social media use. For half of those children, the app also limits access to social apps. The researchers expect to publish their first results in the middle of next year, after the newly announced ban has taken effect. However, at the Wellcome Trust says the findings should still help inform policy.

They will also improve upon existing research that tends to rely on self-reported measures, like asking children or their parents how much time they spend on social media, rather than using more objective metrics. What鈥檚 more, the few interventional studies that do exist . 鈥淚f you鈥檙e talking about big changes here around mental health and those sorts of things, you鈥檙e not going to see changes in two weeks,鈥� says Etchells.

Australia鈥檚 ban came into place in December, which is too recent to gauge its long-term effects. But once national bans like these are in place, it is impossible to do controlled studies, in which two groups of similar people are allocated access or not. What鈥檚 more, the results from larger studies on the wider population before and after the ban will be impossible to unpick from other social impacts.

For now, Sebastian is gearing up to run additional studies that hopefully generate at least some results soon after the ban. The UK government expects to bring legislation to Parliament before Christmas, with the policy coming into force in early 2027.

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The Wellcome Trust has invited 14 research teams to submit plans, some or all of which will be funded, into the effects of social media on young people鈥檚 well-being. These will take varying approaches to capture as much data as possible, with the goal of eventually synthesising the data into a conclusive result.

Some of these studies will follow existing cohorts and regularly interview them about their mental health and well-being over time, before and after the ban. Sebastian says these approaches can be insightful, but rigid. Other studies are proposing momentary assessments, where participants are sent text messages asking them to complete short surveys on the spur of the moment, capturing a different kind of data. Others may look to analyse data that is already being captured for some insight, such as the rate of hospital admissions or school absences.

With time against them, Sebastian hopes that some results could emerge relatively soon after the ban, but they are likely to be nuanced. For instance, a social media ban could have some positive impacts, but also disruptive ones in the short term, as online supportive networks are lost.

The effects of such bans are also likely to change over the years or decades, as today鈥檚 children and younger teenagers approach adulthood having never had access to social media. 鈥淚t鈥檚 not that this is a done deal,鈥� says Sebastian. 鈥淧olicies could be continuing to change over the longer term, and it鈥檚 possible that the findings from our study and others will help to shape those policies iteratively.鈥�

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For now, some are wary that the UK government is taking a reactive stance in the complex problem of poor youth mental health, without the appropriate data. at the University of Oxford told the Science Media Centre that a blanket age ban is a 鈥渂lunt tool鈥� and a stronger step than current evidence can support, but adds that the Wellcome research is an opportunity to learn whether these measures will 鈥渉elp, harm or neither鈥�.

One thing that could hinder research 鈥� and undermine government policy 鈥� is the ability of users to skirt the bans. Early reports suggest that facial-recognition technology designed to verify ages online can be , and VPNs make it trivial to聽appear to websites as a user from another country聽where age checks aren鈥檛 mandated.

Surveys in Australia by the Molly Rose Foundation, a suicide-prevention charity, found that 61 per cent of 12-to-15-year-olds who had accounts on restricted platforms before the ban came into force . The organisation said that given the findings, it would be a 鈥渉igh-stakes gamble鈥� for the UK to follow suit at this stage.

Need a listening ear? UK Samaritans: 116123 (samaritans.org); US Suicide & Crisis Lifeline: 988 (988lifeline.org). Visit bit.ly/SuicideHelplines for services in other countries.

In the fight against common childhood illnesses, scientists have turned to an unusual source: the blood of paediatricians. It turns out this is a treasure trove of powerful antibodies that could be used as preventative treatments. These have even outperformed approved antibody therapies against respiratory syncytial virus (RSV) and a common cold virus.

Paediatricians are almost constantly exposed to respiratory viruses, making them a potentially underexplored resource in the hunt for highly potent antibodies against such pathogens. Although antibody therapies are available for preventing infections like RSV 鈥� which infects almost every child by the age of 2 and can trigger severe breathing difficulties 鈥� they only neutralise some strains. But a broader-acting treatment could now be on the cards.

A team including Hui Zhai at the Children鈥檚 Hospital of Chongqing Medical University screened the blood of 10 paediatricians who had been working at the hospital for over a decade. From this, the researchers discovered 56 potent antibodies against RSV from the paediatricians鈥� immune cells.

The researchers then generated artificial versions of these antibodies and tested them in the lab, finding that three were particularly active against a diverse range of RSV strains. One of the three also neutralised human metapneumovirus, which belongs to the same virus family as RSV and is a common cause of colds, but can also lead to severe illness in some children.

Subsequent tests in mice and rats showed that injections of these three paediatrician-derived antibodies, either on their own or in combination, stopped the animals from developing symptoms when they were infected with RSV or human metapneumovirus. In fact, the paediatrician antibodies were up to 25 times better at blocking RSV than existing antibodies called nirsevimab and clesrovimab, and they neutralised a wider range of strains.

This makes sense because it is common lore among paediatricians that they become increasingly resilient to respiratory viruses over the course of their careers, says at Port Macquarie Base Hospital in Australia. 鈥淚鈥檝e been working with paediatric patients for 10 years now and in my first few years, I would probably get two to three notable respiratory illnesses per year, and now I can go a year without getting any.鈥�

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Calcutt believes the paediatrician-derived antibodies appear promising enough to warrant further testing in human clinical trials. 鈥淭here are certainly stranger interventions out there, so I think this one is worth considering,鈥� he says.

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Currently, there are two ways to protect infants from RSV. One is to administer a vaccine during pregnancy, which protects babies once they are born. The other is to give them an injection of nirsevimab or clesrovimab, which neutralise the virus if a child catches it, thereby helping to prevent severe symptoms. But these only work against some RSV strains.

Nirsevimab and clesrovimab were similarly developed by screening the blood of adults who had previously been infected with RSV, but who didn鈥檛 work in healthcare. This identified antibodies that the individuals鈥� immune systems had naturally produced against the virus. There is no approved vaccine or antibody therapy for human metapneumovirus.

An unprecedented look at how the gut microbiome varies among babies in different parts of the world reveals that infants in the West lack a microbe that is common elsewhere. This could aid the development of probiotics, which are sometimes given to premature babies, that are tailored according to where the infant lives, to maximise the chance of these bacteria becoming established.

The first 1000 days of a child鈥檚 life are very important for seeding their microbiome, which influences everything from their immune function and mental health to their future disease risk. Our understanding of this was almost exclusively limited to infants in the West, but now, a global atlas of baby microbiomes is finally providing a broader picture.

at the Wellcome Sanger Institute in South Cambridgeshire, UK, and his colleagues sequenced more than 1900 genomes of a bacterium called Bifidobacteria longum, which has been .

These were taken from stool samples collected across the UK, Sweden, the US, and seven countries in South Asia and sub-Saharan Africa: Bangladesh, Pakistan, Kenya, Malawi, Burkina Faso, Uganda and Zimbabwe.

They zeroed in on two subspecies of B. longum: B. longum longum and B. longum infantis, which have been the focus of most previous infant gut microbiome studies. By combining their data with genomes sequenced in prior studies, the researchers found that around 70 per cent of infants from the African and South Asian countries had B. longum infantis in their guts by 2 months old, compared with fewer than 2 per cent of babies from the UK, US and Sweden. 鈥�Infantis is basically missing in Western settings,鈥� says Shao.

In contrast, B. longum longum had established in the guts of about a third of infants from these Western countries by 2 months, compared with fewer than 10 per cent of those across the African and South Asian countries.

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This suggests that B. longum longum and B. longum infantis 鈥� which both help to develop the immune system and prevent gut and blood infections 鈥� are primarily found in distinct regions, says Shao.

This is probably because they thrive on different diets, he says. 鈥�Bifidobacteria help to digest nutrients from breast milk, and the composition of this varies with the mother鈥檚 diet, so it could be that longum [longum] is better adapted to a Western diet while infantis thrives on diets in other regions,鈥� he says. The babies without either B. longum longum or B. longum infantis probably had other, similar bacteria established in their gut microbiome, , says Shao.

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This study increased the number of B. longum genomes from South Asia that scientists have ever analysed by about 17 times, and those from Africa by around 11 times. 鈥淭his is a huge step forward for underrepresented populations,鈥� says at the University of Birmingham, UK.

Probiotics are not generally recommended for full-term babies, but are . Off the back of this study, probiotics could be tailored to the region that the premature infant is from, says Hall. For instance, B. longum infantis probiotics may benefit those in parts of Africa and Asia, but it may not persist as well in the guts of Western infants. 鈥淥nly by understanding how bacteria differ in various places can we understand which probiotics are going to be the best for kids in particular parts of the world,鈥� she says.

Babies born into vegan or vegetarian families may be slightly underweight in early infancy, but seem to catch up to their omnivore peers by age 2.

that a well-planned vegan diet 鈥� rich in vegetables, beans, whole grains and fortified products 鈥� can provide all the nutrients needed for good health. But it can still be very difficult to meet a child鈥檚 growing nutritional needs, with veganism being linked to amino acid and protein deficiencies.

When it comes to the pros and cons of veganism at a young age, small studies have provided conflicting results. To address the issue on a wider scale, at Ben-Gurion University of the Negev in Israel and her colleagues have now analysed data on 1.2 million babies collected from national family care centres in Israel between 2014 and 2023, following records of each baby鈥檚 length, weight and head circumference from birth to 24 months.

The team then compared those growth rates to the type of diet that the babies鈥� parents reported having when the infants were about 6 months old. The vast majority of the households said they were omnivorous, with just 1.2 per cent self-reporting as vegetarian and 0.3 per cent as vegan.

But this still accounted for about 18,000 babies in the vegetarian and vegan families. 鈥淏ecause of the massive scale of this study, even a low percentage represents a large enough number of children to be statistically significant and provide reliable evaluations,鈥� says at Tel Aviv University in Israel, who wasn鈥檛 involved in the study.

In the first 60 days of life, the babies鈥� length, head circumference and rates of restricted growth and development were similar across all diet groups. Babies in meat-free families, however 鈥� particularly those in vegan households 鈥� were slightly more likely to be underweight. Being overweight was rare overall, but tended to be less common in the vegetarian and vegan households.

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By around age 2, those differences had largely evened out, with growth measures converging across all three groups. Restricted growth was more common among the toddlers from vegetarian and vegan families, but the differences were small and not statistically significant, says Avital. The researchers accounted for factors that could influence the results, such as income, maternal age and breastfeeding.

鈥淭he results are quite heartening,鈥� says Avnon. 鈥淚t is deeply reassuring to see large-scale data confirming that children of vegetarian and vegan mothers can expect a healthy developmental future.鈥�

The study falls in line with medical observations that babies born small for their gestational age usually 鈥渃atch up鈥� later on, says Avnon. It should also provide reassurance that meat-free diets can support healthy early growth, he says, but points out that the diets were self-reported by the parents, which could affect the accuracy of the results. 鈥淪pecifically, this study lacks a precise, day-to-day evaluation of the child鈥檚 actual nutrition during their early years, which remains a critical factor in long-term development,鈥� he says.

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at the Hospital for Sick Children in Toronto, Canada, questions whether the slight variations in restricted growth that the researchers found might be a cause for concern down the line. 鈥淭he small but appreciable differences in growth between the three groups could well be relevant long term, especially given evidence from elsewhere that vegan diets are associated with lower bone mineral density and micronutrient status,鈥� he says.

He therefore cautions against interpreting the findings as reassurance that vegan and vegetarian diets are always appropriate in early life, especially in parts of the world where malnutrition is prevalent.

Although the study was carried out in Israel, Avital says the results probably apply to countries with similar incomes and accessible healthcare, such as the UK. Bhutta now wants to see larger studies that more accurately collect information on diet, as well as factors like parental height.