About two years ago, Alphonso Evans went to the hospital for what he thought was just another bladder infection and ended up in intensive care. In an effort to combat antibiotic-resistant superbugs, scientists have created "living antibiotics" made of viruses that have been genetically modified using the gene-editing tool CRISPR.
A blood test developed by Harvard researchers checks for evidence of past infection with more than a thousand strains of virus, from about 200 virus families. The swine flu virus shown here, A/CA/4/09, rarely infects humans.
C. S. Goldsmith/CDC