Yes. Pneumonia is infection of the lungs. There are various types of pneumonia and various agents cause it (infectious and non-infectious). Infectious pneumonia is caused by either virus or bacteria. The vaccine that you have given to your baby works against bacterial pneumonia. Also vaccines tend to provide immunity against a certain disease. Also it reduces the risk of complications associated with any disease. But giving vaccine doesn't mean your child would never get the disease. He might get infected but the severity would be low. Also 18 months babies are more prone to viral pneumonias.
Next Steps
If your baby is having excessive cough and cold kindly see a pediatrician immediately. Where do you stay? I have my clinic in Palava City, Thane, Maharashtra. You can come and see me tomarrow. Meanwhile you give him Syp. Brozeet LS 2.5 ml three times a day and Syp Montair LC Kid 2.5 ml two times a day.
Health Tips
If your kid is having fast breathing please check his oxygen saturation. He might be having respiratory distress. He will require nebulisation. And if it is serious he might need hospitalisation and oxygen support as well. So just access him and get him to the doctor asap.