Health and wellbeing: The latest news and research

The BA.2 subvariant of the Omicron COVID-19 variant is now dominant worldwide, reports Reuters. BA.2 accounts for nearly 86% of all sequenced cases, according to the World Health Organization (WHO). It's thought to be even more transmissible than other Omicron subvariants BA.1 and BA.11, but isn't thought to be more likely to cause severe disease.

The news follows a WHO warning earlier in March that the COVID-19 pandemic is "far from over".

Google plans to use smartphones to monitor health, with the company saying it would test whether capturing heart sounds and eyeball images could help people identify issues from home.

Costa Rica will legalize the use of marijuana for medical purposes, after passing a bill at the start of March. The bill also allows the cultivation of marijuana for industrial use. However, recreational use and sale will remain banned.

Around half a million refugees from Ukraine who have fled to Poland need support for mental health disorders, the WHO warned last week. About 30,000 have severe mental health problems. Refugees arriving in Poland are suffering from a range of health issues, including diarrhoea and dehydration, but the main need is for support due to trauma, WHO representative in Poland Paloma Cuchi told a briefing in Geneva.

The world faces a "dangerous moment" in the fight against diseases like polio, a senior WHO official warned in mid-March. Efforts are under way to immunize 23 million children across five African countries after an outbreak in Malawi, which declared its first case of wild poliovirus in 30 years in February.

Bed nets treated with a new kind of insecticide cut malaria cases in children by almost half in a large trial in Tanzania, according to a study in The Lancet. This has raised hopes of a new weapon in the fight against the disease. Bed nets have been instrumental in the world's vast progress against malaria in recent decades, with millions of lives saved. But progress has stalled in the past few years, in part because the mosquitoes that spread the infection have increasingly developed resistance to the insecticide used in existing nets.

Global obesity rates are likely to double by 2030 compared with 2010, according to research published in March. The fourth World Obesity Atlas found that more than a billion people across the globe will be obese by 2030. The report, produced by the World Obesity Federation, also found that no country is set to meet the WHO's target to halt obesity by the middle of this decade.

Climate change could make seasonal allergies worse, according to a new study from the University of Michigan, published in Nature Communications. It finds that by the end of the century not only could the allergy season last longer, but the annual level of pollen emitted may also be higher.

Children who spend more time using screens, such as handheld devices, or watching television are more likely to show behaviour problems, according to a study published in JAMA Psychiatry. The research reviewed data from 87 previous studies, involving nearly 160,000 participants, and found more daytime screen use was associated with a 20% higher risk of problems including aggression, anxiety and depression.

Drinking coffee – in particular two or three cups per day – could benefit the heart, according to studies presented at the American College of Cardiology's 71st Annual Scientific Session. The studies found that coffee drinkers have a lower risk of heart disease and dangerous heart rhythms, and could also live longer. However, the study did have limitations, including being unable to control for dietary factors, or adjust for anything added to the coffee, such as milk or sugar.

Those with type 2 diabetes have a higher risk of 57 other health conditions - including cancer and kidney disease - according to a new study at the University of Cambridge. “This study illustrates in alarming detail the unacceptable prevalence of poor health in middle-aged people with type 2 diabetes, and is a stark reminder of the extensive and serious long-term effects of diabetes on the body,” said Dr Elizabeth Robertson, the director of research at Diabetes UK, the Guardian reports.