The following types of co-infections were confirmed: subtype A/H1N1/pdm09 with subtype A/H1N1/ (4 cases), subtype A/H1N1/pdm09 and subtype A/H3N2/ (2 cases), subtype A/H1N1/ and influenza virus B type (1 case), subtype A/H1N1/pdm09 and influenza type B (15 cases), and co-infection of unsubtyped type A with type B virus (51 cases).

Co-infections were reported in people of all ages, from month 1 to 90 years of age. Most co-infections caused by influenza viruses were reported among children up to 4 years of age (22 cases), in the other age-groups the number of co-infections was lower: 5–9 years – 18 cases, 10–14 years – 5 cases, 15–25 years – 3 cases, 26–44 years – 3 cases, 45–64 years – 9 cases, and ≥ 65 years of age – 13 cases (Table 1).

In the epidemic season 2015/2016 co-infections between influenza viruses and influenza-like viruses and among influenza-like viruses were noted, as shown in Table 2. Seventeen cases co-infections with influenza and influenza-like viruses were recorded. The following types of co-infections were confirmed: subtype A/H1N1/pdm09 and RSV (5 cases), A/H1N1/pdm09 and RSV and RV A/B (3 cases), A/H1N1/pdm09 with influenza type B virus and RSV (1 case), A/H1N1/pdm09 and hCoV OC43 (2 cases), A/H1N1/pdm09 and influenza type B virus and hCoV OC43 (1 case), A/H1N1/pdm09 and influenza type B virus, hMPV and RSV (1 case), influenza virus type A and RSV (2 cases), influenza virus type A and hCoV OC43 (1 case), and influenza virus type A with RV A/B (1 case). Furthermore, six co-infections of influenza-like viruses were confirmed: RSV and hCoV 229/NL63 (2 cases), RSV and RVA/B (1 case), RSV and PIV-1 (1 case), AdV and hCoV 229/NL63 (1 case), hCoV 229/NL63, and RSV and PIV-2 (1 case) (Table 2).