The commonest pulmonary infection is the Influenza (A&B). Commonly known as the flu. It usually presents itself just before the monsoon in Chennai. Fever and upper respiratory symptoms start to travel down to the chest causing more severe problems. It is a viral infection that spreads easily. It can be prevented by a killed virus vaccine and is given intramuscularly as a single dose. The virus constantly mutates and so a new batch has to be prepared every year. The vaccine becomes effective against the virus 2 weeks after administration. The best time to receive vaccination is just before the peak influenza season which begins in October. This vaccine provides adequate protection against HINI infection too.
Then comes the Community acquired pneumonia commonly caused by Streptococcus pneumoniae. This is a bacterial infection in contrast to the Flu. Again the symptoms range from mild to very severe. It is impossible to protect against all the strains of this bacteria. Fortunately, the most common strains are now available for vaccination.
The two common vaccines are the conjugated Vaccine with 13 serotypes and the polysaccharide vaccine consisting of polysaccharides from 23 serotypes. Although the latter has more serotypes it is less immunogenic.
The PCV13 is approved in India, for use in adults aged >50 years while the PPSV23 is indicated in those over the age of 65. The vaccine is also indicated for those with CKD, cirrhosis, diabetes, HIV, lupus, cancer and those on chemotherapy or radiotherapy, long-term steroid, asplenia, or splenectomy.
The PCV13 is given as a single dose intramuscularly. A single dose PPSV23 is also recommended in adults as an intramuscular injection. If PCV 13 is given first, it can be followed by PPSV23 after a minimum interval of 8 weeks. Revaccination is to be done with PPSV23 at least 5 years after the first dose. If PPSV23 has been given earlier PCV can be given after 1 year. This combination results in mucosal immunity and lifelong immunity.
Of course, vaccines are administered either by subcutaneous or intramuscular injection using syringes and needles. Needle phobia and the need for trained healthcare workers then becomes a limitation. Newer delivery strategies such as direct delivery to the lungs are being looked at.
Side effects mostly only include allergic reactions. And these are rare too.
Either way prevention is better than cure. So, vaccination is here to stay.