Bacteria in the gut influence the production of antibodies and themselves secrete metabolites. In a pregnant woman, these compounds may influence immune development of her fetus.

As researchers test existing vaccines for nonspecific protection against COVID-19, immunologists are working to understand how some inoculations protect against pathogens they weren’t designed to fend off.

The scientific community said goodbye to a number of leading researchers this year.

Editor's Note: Since 1993, the newsletter Science Watch has ranked the year's most cited scientists and research papers. Based on records compiled by the Philadelphia-based Institute for Scientific Information (ISI), analysts prepared such rosters for 1994. Researchers are ranked by their number of "hot papers." An article is considered "hot" if it has garnered a substantially greater number of citations, within a two-year period, than other papers in similar disciplines. For instance, the 199