A Pneumonia Case Associated with Type 2 Polio Vaccine Strains

Since the World Health Assembly endorsed a plan to completely eradicate polio in 1988, the large‑scale use of the attenuated oral poliovirus vaccine (OPV) has drastically decreased the number of polio cases. However, the OPV vaccine brings rare but serious adverse consequences, especially in the Type 2 vaccine strains. Most vaccine‑associated paralytic poliomyelitis (VAPP) outbreaks are associated with Type 2 polio vaccine strains, and approximately 26–31% of genetically divergent vaccine‑derived polioviruses (VDPVs) cases are associated with the Type 2 component of OPV. Other than VAPP cases and VDPVs, Type 2 polio vaccine strains can also cause a variety of illnesses. To the best of our knowledge, no cases of pneumonia resulting from Type 2 polio vaccine strains have been reported. However, here we report an infant case associated with the Type 2 polio vaccine strain. A 3‑month‑old male infant with no underlying diseases was admitted to Beijing Haidian Hospital on July 31, 2015, where he was diagnosed with lobular pneumonia exactly 26 days after he had received his second dose of trivalent OPV (tOPV). The infant was born from a second regular pregnancy by normal delivery (35/36 weeks gestation, birth weight: 3550 g). The infant also received two birth dose vaccinations (the Bacillus Calmette–Guerin vaccine and hepatitis B vaccine), and no adverse reactions to the vaccinations were reported. The infant had no signs of immunodeficiency. His family had no history of travel in the months before he became ill. days after his second dose of tOPV, he developed a fever, concomitant cough, some phlegm, and his body temperature reached 40°C. An antibiotic was given by intravenous drip for 3 days in a local hospital in Anhui Province, but a low‑grade fever and cough persisted until his hospitalization in Beijing Haidian Hospital. Blood tests in the Haidian Hospital revealed the following results: the total white blood cell count was 1. 11 /L; and hemoglobin was 110 g/L. The laboratory tests showed that the C‑reactive protein was 5.0 mg/L (normal range ≤10.0 mg/L). Chest radiographs showed thickness or turbulence in the texture in both lungs and blotches of shadows in the right lung. Further clinical features were respiratory sounds and pulmonary rales. In the hospital, treatments included antibiotic therapy and respiratory management such as aerosols, suctioning, back therapy, and body positioning. He was given intravenous tazobactam sodium 1 g/d and ambroxol hydrochloride and Ge injections 15 mg/d. After 3 days of treatment, …