Pfizer and Moderna vaccines may offer immunity for years

A study published in Nature is the first to confirm the presence over time of germinal centers of B cells that ‘train’ antibodies. Until now, the immunity generated by vaccines against Covid-19 is measured by ‘weighing’ the amount of neutralizing antibodies, which prevent the coronavirus…

This is the mysterious plague that killed the Aztecs 500 years ago

The epidemic called ‘cocoliztli’, which killed 80% of the native population of Mexico, was caused by a Salmonella infection. During the 16th century, many large-scale epidemics spread throughout the New World, but their biological causes are difficult to determine based on symptoms described in historical…