FIG. 1.
Map of Poland. The medical centers collaborating in this study are as follows: 1, Mother and Child Institute, Warsaw; 2, Health Care Center Praga-Polnoc, Warsaw; 3, Nieklanska Street Hospital, Warsaw; 4, Sienna Street Hospital, Warsaw; 5, Health Care Center, Kolobrzeg; 6, Regional Hospital, Gdansk; 7, Health Care Center, Tczew; 8, Health Care Center, Braniewo; 9, Regional Children’s Hospital Olsztyn; 10, Regional Hospital, Suwalki; 11, Medical University, Bydgoszcz; 12, Health Care Center, Gorzow Wielkopolski; 13, Health Care Center, Czestochowa; 14, Health Care Center, Kedzierzyn Kozle; 15, Jan Bober Center for Microbiology and Autovaccines, Krakow; 16, Health Care Center, Myslenice; 17, Health Care Center, Mielec; 18, Health Care Center, Sanok; and 19, Regional Hospital, Lomza.