IN SINGAPORE, there are currently two pneumococcal vaccines available commercially here. The heptavalent pneumococcal conjugate vaccine is marketed for children but is not on the national immunisation programme's list of vaccines.

Hsu Li Yang, consultant, division of infectious diseases, university medicine cluster of the National University Hospital, says that he understands from surveys that the uptake for this vaccination is between 15 and 20 per cent.

The adult 23-valent vaccine and haemophilus influenza B vaccine are also not on the national immunisation programme's list of vaccines, and it is not known what the rate of uptake is. But Dr Hsu would certainly recommend that adults who fall into the known risk groups for severe pneumococcal disease and children be vaccinated.

This includes adults who are above 60 years old; and children below two years old, who are immuno-compromised due to chronic illness, or who are undergoing chemotherapy or radiotherapy.

'Patients with severe influenza infection can get a bacterial superinfection of the lungs - usually with staphylococcus aureus (there is no vaccine for this) and streptococcus pneumonia, and die from that,' says Dr Hsu. This is the main cause of death in the majority of flu pandemics as well as seasonal influenza.

Patients may also get a viral pneumonia with accompanying 'cytokine storm' - that is, an exaggerated immune system response to the infection - and die as a consequence.

This was believed to be the primary cause of the flu-related deaths during the Spanish flu outbreak in 1918-1919, and is the primary cause of death for avian (H5N1) influenza as well.

This article was first published in The Business Times.