Health briefs
Early periods
A Harvard University study of more than 70,000 American women born between 1950 and 2005 has shown girls are getting their periods earlier. The percentage whose first period would be classified as early or very early has nearly doubled. While a higher body mass index could explain about half of the early start times observed in the study, stress, poor nutrition and environmental pollution could also play a role.
Covid protection
Covid-19 vaccines available in NZ are still effective, especially against hospitalisation and death, but efficacy has dropped as new variants come through, according to research from the University of North Carolina. The team compared outcomes in about 1.8 million people in the US, about 12% of whom had one of the newer vaccines currently on offer here targeting subvariant XBB 1.5. Compared with the general population (including unvaccinated people and those who had earlier vaccines) researchers calculated the XBB 1.5 vaccines were 52% effective against symptomatic infection after four weeks and 67% effective against hospitalisation after four weeks.
Dry flying
A glass of wine helps pass the time on a long flight but alcohol and cabin pressure may be bad for heart health, say researchers from the German Aerospace Centre. The combination can lower blood oxygen levels and raise heart rates, even in young and healthy individuals. To work this out, they had people sleep in a lab with air pressure that mimicked the cabin pressure of a plane cruising at close to 2500m. Those who were provided with alcohol before going to sleep had falls in their blood-oxygen levels and higher heart rates compared with participants l who had no alcohol.